The Gilbertiodendron ogoouense species complex (Leguminosae: Caesalpinioideae), Central Africa

Summary

The Gilbertiodendron ogoouense species complex consists of 14 tree species. Eight species are here newly described and one is here reinstated: G. bambolense Burgt; G. breteleri Burgt; G. ebo Burgt & Mackinder; G. ecoukense (Pellegr.) Burgt; G. maximum Burgt & Wieringa; G. minkebense Burgt & Estrella; G. quinquejugum Burgt; G. scutatum Wieringa & Estrella and G. sulfureum Burgt. Five species in the complex were already recognised as accepted: G. brachystegioides (Harms) J. Léonard; G. klainei (Pierre ex Pellegr.) J. Léonard; G. newberyi Burgt; G. ngouniense (Pellegr.) J. Léonard and G. ogoouense (Pellegr.) J. Léonard. All 14 species are medium-sized or large trees of evergreen rain forest on well-drained or periodically inundated soil, at 0 – 900 m altitude. Each of the 14 species is distributed in one or more of the following Central African countries: Cameroon, Equatorial Guinea, Gabon, Congo (Brazzaville), Angola (Cabinda) and Congo (Kinshasa). Included are a key, a table comparing the main morphological characters, illustrations drawn to the same scale and distribution maps of all species. The conservation status of all species is assessed according to IUCN categories and criteria: G. maximum is classified as Critically Endangered, G. ebo and G. newberyi as Endangered, G. breteleri, G. klainei, G. minkebense, G. ngouniense and G. scutatum as Vulnerable, and the remaining six species as Least Concern.

Introduction

Gilbertiodendron (Leguminosae – Caesalpinioideae) is a West and Central tropical African genus, described by J. Léonard (1952a); who transferred 25 African species of Macrolobium, including M. ogoouense Pellegr., to Gilbertiodendron (Léonard 1952a, 1954). The genus was redelimited by the inclusion of the monotypic genus Pellegriniodendron in Gilbertiodendron (Estrella et al. 2012). A genus description and taxonomic history is given by Estrella & Devesa (2014) and Lewis et al. (2005). The 11 species of Gilbertiodendron from West Africa (Guinea to Ghana) have been revised by Estrella & Devesa (2014). The present paper revises a group of Central African species of Gilbertiodendron and as a result, the total number of species within the genus Gilbertiodendron is now 39 (African Plants Database 2014; Estrella & Devesa 2014; this study).

Gilbertiodendron species are medium-sized understory trees to large canopy trees, sometimes over 50 m high, occurring in evergreen rain forest and gallery forest on well-drained soil or periodically inundated soil (Aubréville 1968, 1970; Hawthorne & Jongkind 2006; Burgt pers. obs.). Trunks are cylindrical without buttresses and the bark is usually yellowish light brown, often covered in small soft flakes that fall slowly to the ground when the bark is wiped by hand (Burgt pers. obs.).

The species Macrolobium ogoouense was described by F. Pellegrin in 1941 and transferred to Gilbertiodendron ogoouense (Pellegr.) J. Léonard 1952a. In the Flore du Gabon and the Flore du Cameroun (Aubréville 1968, 1970), G. ogoouense keys out having 2 – 8 pairs of leaflets, small bracteoles of 1 cm long and a pod with 3 longitudinal ridges. Aubréville (1968, 1970) mentions that “It is possible that there are at least two different but closely related species present in G. ogoouense”. During field surveys in Cameroon and Congo (Brazzaville) and naming of the collected specimens at WAG and K, the first author came across four different species that all key out as Gilbertiodendron ogoouense using Aubréville (1968, 1970).

Research on the ecology and dynamics of Caesalpinioideae tree species in Korup National Park, Cameroon, in the years 1999 – 2005 (Newbery et al. 2004, 2013), resulted in collections of two species of Gilbertiodendron, which both key out (following Aubréville 1968, 1970) as G. ogoouense. However, these two species presented clear differences, not only in characters seen on herbarium specimens, but also in characters observed on the trees in the forest. The specimens of one of these two species morphologically match the lectotype of G. ogoouense collected in Gabon (Le Testu 6368). The other species was described as G. newberyi Burgt (Burgt et al. 2012).

During a vegetation survey in Lékoumou Préfecture, Congo (Brazzaville), in 2009 – 2010, botany teams often including the first author made a number of collections from Gilbertiodendron trees which all key out (following Aubréville 1968, 1970) as G. ogoouense. However, these collections represent three different species. One of the three species was collected in flower and fruit (M’Boungou 144, 387). These collections match well the type of Macrolobium ecoukense Pellegr. which was treated as a synonym of G. ogoouense by Léonard (1954) but is here reinstated and formally transferred to Gilbertiodendron. The second species was collected in fruit (Bongou 105), and was identified to belong to a new species of which several flowering collections from Gabon and Angola (Cabinda) had already been collected by other botanists. The third species could only be collected sterile (Cheek 17030, Mpandzou 44) and was identified as G. ogoouense s.s.; flowering material should be collected for confirmation.

The herbarium specimens that were previously named to Gilbertiodendron ogoouense (mainly those found in the herbaria BR, IEC, K, LBV, MO, P, WAG and YA) show considerable variation in morphological characters. For example, the maximum number of pairs of leaflets varies between 2 and 10. A preliminary study of these specimens resulted in the conclusion that the specimens previously named to G. ogoouense can be separated into about 10 species and the existence of a G. ogoouense species complex was proposed (Burgt et al. 2012). The present morphological study has determined that G. brachystegioides (Harms) J. Léonard, G. klainei (Pierre ex Pellegr.) J. Léonard and G. ngouniense (Pellegr.) J. Léonard are part of this complex. The results of a phylogenetic study of Gilbertiodendron (Estrella et al. 2014) show that this complex constitutes a strongly supported monophyletic clade. The aim of the present study is to revise the G. ogoouense species complex and to correctly name all fertile specimens named previously as G. brachystegioides, G. klainei, G. ngouniense and G. ogoouense.

Materials and methods

The herbaria BM, BR, BRLU, IEC, K, MPU, P, SCA, WAG and YA were visited and all specimens found under Gilbertiodendron were studied. Specimens borrowed from the herbaria AAH, AAU, B, C, COI, E, G, GOET, H, HBG, IFAN, LISC, MA, MO, NY, PRE, S, US, WU and Z; and digital images of the holdings of Gilbertiodendron at LBV were also examined. The majority of herbarium specimens were examined first hand but some specimens were diagnosed using images on the internet. All specimens that were named to species in the G. ogoouense species complex are cited. All holotypes have been seen by the authors; any isotypes also seen are indicated by an exclamation mark. Isotypes which have not been seen but likely exist are cited without exclamation mark. All other cited specimens and duplicates have been seen by the authors; they are cited without exclamation mark.

Most characters were studied using dry material from herbarium specimens. Measurements of pedicels and bracteoles were also made using dry material. Other floral measurements were made on rehydrated material or on spirit preserved material, which was dissected and measured under a microscope. Stipules and leaves were only measured on collections taken from mature trees. Measurements between brackets are also derived from specimens of mature individuals, but indicate extreme values seen only on a single collection, or on several collections but then rarely. If measurements are derived from material taken from juvenile trees, then that is noted in the text. The terminology used in the descriptions follows Beentje (2010). All species in this paper are illustrated, and all the illustrations were drawn to the same scale. Open flowers are not illustrated with the exception of those of Gilbertiodendron ogoouense, because the interiors of the flowers of the species presented here do not show large differences and because well-developed open flowers are absent on many flowering collections. Although Gilbertiodendron trees may be in flower for a period of up to nine weeks (Burgt 775), open flowers usually develop only every few days and then wilt the same day.

All existing and newly described Gilbertiodendron species in this paper are assessed for conservation status using the criteria defined by the IUCN (2014). The number of localities and the extent of occurrence of all species were calculated using Geocat (2014). The number of localities where a species occurs is considered to be the number of collections made at more than 2 km distance to each other. Some collections were made up to c. 110 years ago. The assessments were made assuming that the species are still present in those localities, although that may not always be true.

Results

The Gilbertiodendron ogoouense species complex consists of 14 tree species. Eight species are here newly described and one is here reinstated: G. bambolense Burgt; G. breteleri Burgt; G. ebo Burgt & Mackinder; G. ecoukense (Pellegr.) Burgt; G. maximum Burgt & Wieringa; G. minkebense Burgt & Estrella; G. quinquejugum Burgt; G. scutatum Wieringa & Estrella and G. sulfureum Burgt. Five species in the complex were already recognised as accepted: G. brachystegioides; G. klainei; G. newberyi; G. ngouniense and G. ogoouense. All 14 species are medium-sized or large trees of evergreen rain forest on well-drained or periodically inundated soil, at 0 – 900 m altitude. Table 1 shows the distribution of the 14 species in the Central African countries.

Table 1. IUCN conservation status categories and criteria of the 14 species in the Gilbertiodendron ogoouense species complex.

Of the 14 species in the present study, nine have been sampled for a phylogenetic study by Estrella et al. (2014): Gilbertiodendron brachystegioides, G. breteleri, G. ecoukense, G. klainei, G. maximum, G. newberyi, G. ogoouense, G. quinquejugum and G. scutatum. That study confirmed the placement of each of these nine species within the G. ogoouense species complex. Of the remaining five species, G. bambolense, G. ngouniense and G. sulfureum on morphological grounds certainly belong in the complex; while G. ebo and G. minkebense on morphological grounds likely belong in the complex.

Three species in the Gilbertiodendron ogoouense species complex, G. brachystegioides, G. ngouniense and G. ogoouense, could consist of more than one taxon; see the notes sections of their species descriptions.

Why new species, not subspecies or varieties?

The differences between some of the species presented here are small. This brings up the question why they are here described as species and not as subspecies or varieties. Some of the reasons for this are derived from the observations made by the first author on trees of Gilbertiodendron ogoouense and G. newberyi in Korup National Park, Cameroon.

The differences between these two species as seen on herbarium specimens from Korup are small. The main difference is in the number of pairs of leaflets: 2 – 3 pairs in Gilbertiodendron ogoouense; 3 – 5 (– 6) pairs in G. newberyi. The number of pairs of leaflets was not only checked on herbarium specimens, but also in the forest on trees over 10 cm DBH: 107 trees of G. ogoouense and 57 trees of G. newberyi. All trees could easily be assigned to species by way of their number of pairs of leaflets; see the key in Burgt et al. (2012). In addition to the differences visible on herbarium specimens, these trees appeared to show two differences not visible on herbarium specimens. Both species grow in groves of 5 – 18 trees over 50 cm dbh; the groves of one species are completely or at least partly separated from those of the other species (Burgt et al. 2012, map 2). If this was just a single species with a rather variable number of pairs of leaflets, the trees with low and high numbers of pairs of leaflets would be expected to grow more randomly mixed. The second difference is that the bark colour and texture of both species are different (Burgt et al. 2012, fig. 2). Molecular analysis by Estrella et al. (2014) shows that samples from these trees are not direct sisters, so they appear genetically isolated. These field and lab observations are additional evidence that G. ogoouense and G. newberyi are two different species; not subspecies or varieties. This makes it likely that the newly described species within the G. ogoouense species complex are indeed different at the species level.

Most new species recognised here have distinct and often restricted distribution areas, which may partly overlap with those of other species within the Gilbertiodendron ogoouense species complex. If they were all one and the same species (with maybe subspecies) one would expect to find a more clinal transition from one entity into the other; not overlapping distributions with even different distinct entities present in the same forests. In the new entities several characters are correlated with each other, again pointing to genetic isolation. This is corroborated by the molecular results (Estrella et al. 2014). If an entity were based on only a single character one could have considered variety level, although the authors of this paper do not consider that level very useful.

Seed dispersal and grove structure

All species in the genus Gilbertiodendron disperse their seeds by ballistic seed dispersal. The seeds are dispersed by sudden dehiscence of the mature pods. The maximum ballistic seed dispersal distance of the highest tree species in this study is likely around 60 m, measured horizontally from the edge of the tree crown (Burgt 1997). The relatively short and strictly limited maximum ballistic dispersal distance is presumed to be a contributory factor to grove-formation (Burgt 1997; Burgt et al. 2012).

The first author has observed and/or mapped groves of five species of the present study, in Cameroon and Congo (Brazzaville): Gilbertiodendron brachystegioides, G. ecoukense, G. newberyi (Map 2 in Burgt et al. 2012), G. ogoouense (Map 1) and G. quinquejugum. These five species were found to grow in small co-dominant groves. Most of the forest around these groves is devoid of Gilbertiodendron trees. For example, in Congo (Brazzaville), Lékoumou Préfecture, 70 forest plots of 25 m × 25 m were made; 63 plots contained no Gilbertiodendron spp.; 1 plot contained G. ecoukense; 1 plot contained both G. ecoukense and G. ogoouense; and 5 plots contained G. quinquejugum (Cheek & Burgt, unpubl. data). The studied groves in Cameroon and Congo (Brazzaville) typically are more or less circular in shape, 100 – 400 m in diameter and consist of 5 – 18 trees over 50 cm dbh (canopy trees) and 8 – 21 trees of 10 – 50 cm dbh (mostly understory trees); 7% – 30% of the trees over 50 cm dbh and 0.5% – 2% of the trees of 10 – 50 cm dbh belong to a single Gilbertiodendron species.

Map 1

The “NW Plot” (750 m × 750 m) in Korup National Park, Cameroon; with the distribution of all 29 Gilbertiodendron ogoouense trees over 10 cm dbh found there. The size of a dot is relative to the dbh of the tree, which was between 10 and 99 cm (in 2003). The area is under 100% forest cover with canopy trees 30 – 45 m high. Thick lines represent small streams, thin lines are gullies.

In the Minkébé transect data (described by Valkenburg et al. 1998) several groves of Gilbertiodendron minkebense (the name G. ogoouense is used) appear to be broached by the transect line. Stretches of G. minkebense are up to 350 m long, which nicely corroborates the grove size as established in Congo (Brazzaville) and Cameroon. In the Minkébé area these G. minkebense groves are part of larger and denser groves of G. dewevrei (De Wild.) J. Léonard; a species which is not part of the G. ogoouense species complex.

Gilbertiodendron species are usually found co-dominant with other tree species from the Caesalpinioideae subfamily (Burgt pers. obs., Wieringa 1999). Trees of many different species in other families are also present. The groves of the Gilbertiodendron species in this manuscript are therefore not mono-dominant with respect to canopy trees; in contrast to G. dewevrei, a species which is well-known to grow in almost pure stands covering large areas, where virtually all canopy trees belong to this species (e.g. Aubréville 1970; Valkenburg et al. 1998). In Korup National Park in Cameroon, G. dewevrei also grows in almost pure stands (Map 2), but the size of these stands is small, about 0.5 ha only. Gilbertiodendron species in the G. ogoouense species complex may have different ecological and regeneration strategies compared to G. dewevrei (compare Maps 1 and 2). The latter species seems to form relatively even-sized, presumably even-aged stands, and trees grow closer to each other (Map 2).

Map 2

A group of 96 trees of Gilbertiodendron dewevrei in Korup National Park, Cameroon (G. dewevrei is not part of the G. ogoouense species complex). The size of a dot is relative to the dbh of the tree, which was between 10 and 213 cm (in 2004). The area is under 100% forest cover with canopy trees 30 – 45 m high. Streams and gullies were not mapped in this area. The centre of the area is 2240 m to the SE of the centre of Map 1.

Local names

In Cameroon, the local names Ekop, Ekobem and Ekoussek are given on the labels of various species within the Gilbertiodendron ogoouense species complex (Foury 2, 38; Letouzey 1462, 2646; W. de Wilde 1306). The name Ekop is used for tree species in several genera within the Caesalpinioideae subfamily (Letouzey & Mouranche 1952). In Gabon, the name “Abeum” is used by Fang ethnic groups for various species of Gilbertiodendron. It is also the forestry name for these species. At least six of the 14 species are known in Gabon by the local name “Abeum” (Aubréville 1968; Saint Aubin 1963; Dibata 1219; Mouandza 248; Moungazi 72; Wilks 1007). Since the Gilbertiodendron species in this manuscript are difficult to distinguish even by botanists, rare species of Gilbertiodendron may be logged and traded under the same name as common species.

Conservation status of the species

Results of the IUCN conservation assessments are presented in Table 1. Brief justifications for the IUCN assessments are presented after each species description. The only species already assessed, Gilbertiodendron klainei, is listed as Vulnerable D (IUCN 2014). It is here proposed to change this to Vulnerable A2cd+3cd. Most of the species in this manuscript are timber trees; therefore species with a large extent of occurrence may still be threatened.

Taxonomy

Specimens of Gilbertiodendron that key out as G. brachystegioides, G. klainei, G. ngouniense or G. ogoouense (as well as G. barbulatum (Pellegr.) J. Léonard which is not part of the G. ogoouense species complex; see below) in the Flore du Cameroun (Aubréville 1970) or the Flore du Gabon (Aubréville 1968) can be further named using the key and Table 2. There exists no single character to distinguish species in the complex from other species in the genus Gilbertiodendron, but the diagnostic characters are summarised in Table 2. The number of pairs of leaflets is one of the most important characters to distinguish the species in the G. ogoouense species complex. The 14 species are therefore presented in Tables 1 and 2 and in the descriptions in ascending order of average number of leaflet pairs.

Table 2. The main characters distinguishing the 14 species in the Gilbertiodendron ogoouense species complex. The species are sorted in ascending order of average number of leaflet pairs. The maximum number of pairs of leaflets is given in brackets if the amount of leaves counted having that many pairs of leaflets is less than 5%, or found on only one out of many collections. Gilbertiodendron barbulatum is included in the table but is not part of the complex; see text.

Gilbertiodendron barbulatum is not part of the G. ogoouense species complex; therefore a description is not included. However, G. barbulatum is included in the key and in Table 2 because this species differs from those in the complex only by characters not used in the key and Table 2. G. barbulatum is not part of the complex because the leaflet glands are placed at both margins away from the petiolule and apex (all species in the complex have the leaflet glands placed near the petiolule and apex). The inflorescence has only 4 – 5 flowers per cm (instead of 6 – 12 flowers per cm) and the ovary is completely hirsute (instead of margins densely hirsute and sides glabrous). In addition to this, Pellegrin (1941) mentions that the large petal has a patch of hairs on the outside of the claw and the anthers have a patch of hairs on the abaxial side (these are glabrous in all species in the complex). G. barbulatum is only known from the type: Le Testu 6411.

Key to the species in the Gilbertiodendron ogoouense species complex

This key can be used to name fertile and sterile material collected from the canopy of mature trees. Material collected from saplings, juvenile trees or stem shoots of mature trees may not always be named with this key. Since the range of the number of pairs of leaflets of the species in the key usually overlaps, it is helpful to have abundant leaves of a specimen.

• 1. Reniform (kidney-shaped) stipules pouched, a pair of stipules strongly inrolled towards each other. . . . . . . . . . . . . . . . 2

• Reniform stipules flat, a pair of stipules not strongly inrolled towards each other; or stipules absent, linear, or fan-shaped. . . . . . . . . . . . . . . . 5

• 2. Leaflets always 2 pairs, to 20 × 8 cm; petiolules 3 – 4 mm long; bracteoles 6 – 7 mm long; Equatorial Guinea, Gabon, Congo (Brazzaville). . . . . . . . . . . . . . . . 1. G. ngouniense

• Leaflets 1 – 10 (– 11) pairs, never only 2 pairs. . . . . . . . . . . . . . . . 3

• 3. Leaflets 1 – 6 pairs, to 28 × 10 cm; petiolules 2 – 11 mm long; bracteoles 9 – 16 mm long. . . . . . . . . . . . . . . . 4

• Leaflets 5 – 10 (– 11) pairs, to 9 (– 11) × 3 (– 5) cm; petiolules 1 – 2 mm long; bracteoles 5 – 6 mm long; Cameroon, Equatorial Guinea, Gabon. . . . . . . . . . . . . . . . 12. G. brachystegioides

• 4. Stipules pouched, a pair of stipules strongly inrolled towards each other; leaflets 1 – 6 pairs, to 28 × 10 cm; petiolules 5 – 11 mm long; bracteoles 12 – 16 mm long; Cameroon. . . . . . . . . . . . . . . . 6. G. ebo

• Stipules flat, occasionally pouched; leaflets 2 – 5 pairs, to 14 (– 16) × 5 (– 8) cm; petiolules 2 – 5 mm long; bracteoles 9 – 11 mm long; Gabon, Congo (Brazzaville). . . . . . . . . . . . . . . . 5. G. minkebense

• 5. Stipules absent, linear or fan-shaped. . . . . . . . . . . . . . . . 6

• Stipules reniform, flat, persistent; usually present on fertile material. . . . . . . . . . . . . . . . 9

• 6. Petiolules 6 – 18 mm long; leaflets 2 – 3 pairs; Gabon. . . . . . . . . . . . . . . . . . . . . . . . 2. G. maximum

  Petiolules 2 – 6 mm long; leaflets 2 – 10 (– 11) pairs. . . . . . . . . . . . . . . . 7

• 7. Leaflets always 2 pairs; stipules linear 8 – 11 × 2 mm; pedicel 9 – 15 mm; bracteoles 7 – 8 mm long; Gabon. . . . . . . . . . . . . . . . (G. barbulatum)

• Leaflets 2 – 10 (– 11) pairs, never only 2 pairs; stipules linear 18 – 30 × 3 mm, or absent. . . . . . . . . . . . . . . . 8

• 8. Stipules absent (caducous linear stipules 4 – 6 × 0.8 mm on juvenile material); leaflets 2 – 4 (– 5) pairs, below smooth; pedicel 3 – 6 mm; bracteoles 5 – 7 mm long; Cameroon to western Congo (Kinshasa). . . . . . . . . . . . . . . . 4. G. ecoukense

• Stipules linear 18 – 30 × 3 mm; leaflets 6 – 10 (– 11) pairs, below papillose; pedicel 5 – 12 mm; bracteoles 8 – 10 mm long; Cameroon, Gabon. . . . . . . . . . . . . . . . 14. G. klainei

• 9. Reniform stipules to 48 × 40 cm, consecutive stipules usually overlapping; leaflets 5 – 9 (– 11) pairs; Equatorial Guinea, Gabon. . . . . . . . . . . . . . . . 13. G. scutatum

• Reniform stipules to 33 × 27 cm, consecutive stipules not overlapping; leaflets 2 – 9 (– 10) pairs. . . . . . . . . . . . . . . . 10

• 10. Leaflets 4 – 9 (– 10) pairs, to 11 cm long; petiolules 1 – 3 mm long; bracteoles 5 – 6 (– 7) mm long; small to medium sized tree from periodically inundated soil; Cameroon, Gabon. . . . . . . . . . . . . . . . 11. G. sulfureum

• Leaflets 2 – 7 pairs, largest leaflets usually over 11 cm long; petiolules 1 – 7 mm long; bracteoles 5 – 11 mm long. . . . . . . . . . . . . . . . 11

• 11. Leaflets 4 – 7 pairs; pedicel 5 – 10 mm; bracteoles 6 – 7 mm long; central and eastern Congo (Kinshasa). . . . . . . . . . . . . . . . 10. G. bambolense

• Leaflets 2 – 6 pairs; pedicel 3 – 23 mm; bracteoles 5 – 11 mm long; Cameroon to Angola (Cabinda). . . . . . . . . . . . . . . . 12

• 12. Leaflets below dull, densely papillose and sparsely persistent puberulent with appressed hairs 0.1 mm long, leaflets 3 – 6 pairs; pedicel 3 – 8 mm; Gabon. . . . . . . . . . . . . . . . 9. G. breteleri

• Leaflets below somewhat glossy, smooth (not densely papillose) and glabrescent to glabrous, leaflets 2 – 5 (– 6) pairs; pedicel 5 – 23 mm. . . . . . . . . . . . . . . . 13

• 13. Leaflets always 2 pairs; pedicel 4 – 5 mm long; bracteoles 6 – 7 mm long; Equatorial Guinea, Gabon, Congo (Brazzaville). . . . . . . . . . . . . . . . 1. G. ngouniense

• Leaflets 2 – 5 (– 6) pairs, never only 2 pairs; pedicel 6 – 23 mm long; bracteoles 5 – 11 mm long. . . . . . . . . . . . . . . . 14

• 14. Leaflets 2 – 3 pairs; pedicel 6 – 11 mm long; bracteoles 5 – 7 mm long; Cameroon, Equatorial Guinea, Gabon, Congo (Brazzaville). . . . . . . . . . . . . . . . 3. G. ogoouense

• Leaflets 3 – 5 (– 6) pairs; pedicel 8 – 23 mm long; bracteoles 5 – 11 mm long. . . . . . . . . . . . . . . . 15

• 15 Leaflets to 8 cm wide, midrib more prominent above; pedicel 16 – 23 mm long; bracteoles 9 – 11 mm long; Gabon, Congo (Brazzaville). . . . . . . . . . . . . . . . 5. G. minkebense

• Leaflets to 6 cm wide, midrib more prominent below; petiolules 1 – 5 mm long; pedicel 8 – 15 mm long; bracteoles 5 – 11 mm long. . . . . . . . . . . . . . . . 16

• 16. Leaflets to 12 × 4 cm; stipules to 15 × 13 mm; bracteoles 8 – 11 mm long; Gabon, Congo (Brazzaville), Angola (Cabinda). . . . . . . . . . . . . . . . 8. G. quinquejugum

• Leaflets to 20 × 6 cm; stipules to 33 × 27 mm; bracteoles 5 – 8 mm long; Southwest Region and Littoral Region in Cameroon. . . . . . . . . . . . . . . . 7. G. newberyi

1. Gilbertiodendron ngouniense (Pellegr.) J. Léonard (1954: 59); Léonard (1957: 238); Aubréville (1968: 217).

Macrolobium ngouniense Pellegr. (Pellegrin 1923: 744). Type: Gabon, Région de la N'Gounié, Sindara, 20 Sept. 1918, G. M. P. C. Le Testu 2290 (holotype P!, [P00391240], isotypes BM!, BR!, E!, LISC!, MO!, NY!, WAG!); as “Macrolobium ngounyense Pellegr.”: Pellegrin (1924: 101); Baker (1930: 674); Pellegrin (1949: 50).

[Macrolobium ogoouense auct. (Pellegrin 1941: 506); in part, for the syntype Le Testu 8407 only; not for its type.]

Tree. Trunk to 50 cm diam. Twigs glabrescent to glabrous. Stipules in pairs, free; reniform part persistent, flat to somewhat inrolled, 12 – 25 × 10 – 20 mm, glabrous; lanceolate part of stipule early caducous, c. 10 mm long. Leaves paripinnate, to 25 × 20 cm; petiole 4 – 9 mm long, 1.5 – 3 mm diam., glabrous; leaf rachis 3 – 9 cm long, glabrescent to glabrous, stipels absent; petiolules 3 – 4 mm long, glabrescent to glabrous. Leaflets papery, opposite, 2 pairs, elliptic to obovate, 5 – 20 × 2 – 8 cm; smooth, somewhat glossy and glabrous both sides, lower surface same colour, midrib glabrous both sides, prominent below; 9 – 10 pairs of secondary veins; leaflet base cuneate to obtuse, slightly oblique; apex acuminate and mucronate, acumen 0.5 – 1 cm long. Glands 0 – 2 per leaflet, 0 – 1 marginal glands at the proximal margin 4 – 22 mm from the apex, 0 – 1 submarginal glands at the distal margin 5 – 13 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 14 cm long, puberulous, hairs to 0.1 mm long, internodes 5 – 10 mm long, lateral axes to 7 cm long, 10 – 12 flowers per cm. Flowers: floral bract inserted at base of pedicel, caducous, ovate, 3 – 4 × 2 – 3 mm, puberulous outside, hairs to 0.1 mm long, centre glabrous inside; pedicel 4 – 5 mm long, puberulous, light-coloured hairs to 0.1 mm long; bracteoles 2, elliptic, 6 – 7 × 5 – 6 mm, puberulous outside, light-coloured hairs to 0.1 mm long, glabrous inside, a few hairs to 0.1 mm long near margin; receptacle 1 mm high, 2 mm diam. at top, glabrous; sepals 5, glabrous, narrowly triangular, c. 4 × 1.5 mm, apex acute; petals 5, alternate to sepals, white, glabrous; adaxial petal not well seen, claw c. 4 mm long, blade bilobed, 4 mm high × 7 mm wide; the other 4 petals c. 3 × 1.5 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 10 mm long; anthers glabrous, 2 mm long; 6 staminodes, filiform, to c. 0.3 mm long, inserted on a staminodal tube c. 0.5 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary 3 × 2 × 0.5 mm, 4 ovules, margins densely hirsute, hairs to 0.8 mm long, sides glabrous; stipe c. 1 mm long; style 10 mm long, lower part hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 10 – 11 × 5 – 6 cm, beak 0 – 2 mm long, sutures not winged; 2 – 2.5 longitudinal ridges running from the base to the apex, parallel to and at 0.3 – 2.3 cm distance to the upper suture. Fig. 1; Map 3.

Fig. 1

Gilbertiodendron ngouniense. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel. A – C from Le Testu 2290 (P). drawn by margaret tebbs.

Map 3

Distribution of Gilbertiodendron ngouniense. Open circles represent collections provisionally included in this species.

distribution. Gilbertiodendron ngouniense is known from Equatorial Guinea, Gabon and Congo (Brazzaville) (Map 3). The presence in Equatorial Guinea and Congo (Brazzaville) needs to be confirmed by flowering specimens.

specimens examined. equatorial guinea. Mosumo, sterile, 17 Jan. 2003, Desmet 275 (BRLU). gabon. Région de la N'Gounié, Sindara, fl., 20 Sept. 1918, Le Testu 2290 (holotype P!; isotypes BM!, BR!, E!, LISC!, MO!, NY!, WAG!); Ogooué-Lolo, région de Lastoursville, Poupa, fl., 7 Oct. 1930, Le Testu 8407 (syntype of Macrolobium ogoouense Pellegr.; BM, BR, HBG, K, LISC, P); Monts de Cristal, proche de Tchimbélé, montagne de Ngol Madouaka, sterile, Feb. 2007, Leal 839 (BRLU); Crystal Mts, 1025 m on transect C, sterile, 17 Nov. 2000, Nguema Miyono 1354 (MO, WAG); same loc., 4900 m on transect D, sterile, 23 Nov. 2000, Nguema Miyono 1432 (WAG); same loc., 575 m on transect E, sterile, 4 Dec. 2000, Nguema Miyono 1506 (MO, WAG); same loc., 2075 m on transect E, sterile, 7 Dec. 2000, Nguema Miyono 1523 (MO, WAG); same loc., 150 m on transect F4, sterile, 22 Jan. 2001, Nguema Miyono 1634 (MO, WAG); same loc., 28900 m on transect G, sterile, 31 March 2001, Nguema Miyono 1810 (WAG); same loc., 55150 m on transect G, sterile, 22 May 2001, Nguema Miyono 1829 (WAG); same loc., 70 m on transect G27, sterile, 2 May 2001, Wilks AP 3421 (BR, MO); same loc., 53540 m on transect G, fr., 6 May 2001, Wilks AP 3505 (BR, MO, WAG). congo (brazzaville). Ogooue-Leketi proposed National Park, near Simonbondo, sterile, 12 Oct. 2009, Moutsambote 6646 (IEC, K).

habitat. Gilbertiodendron ngouniense occurs in evergreen rain forest, at 100 – 800 m asl.

conservation status. Gilbertiodendron ngouniense is assessed here according to IUCN criteria as Vulnerable A2cd+3cd (Table 1). Although the Extent of occurrence is 46.700 km², which is larger than the threshold of 20.000 km², Vulnerable is chosen because the occurrence of G. ngouniense in some of the sites needs confirmation.

notes. One of the four syntypes of Gilbertiodendron ogoouense, Le Testu 8407, is here provisionally included in G. ngouniense. Le Testu 8407 is certainly not G. ogoouense because 100% of the leaves of Le Testu 8407 have 2 pairs of leaflets, while in G. ogoouense only 6% of the leaves have 2 pairs of leaflets and 94% have 3 pairs of leaflets. However, Le Testu 8407 is not completely similar to Le Testu 2290; the type of G. ngouniense. The leaflets of Le Testu 2290 are larger (9 – 20 × 3.5 – 8 cm) in size and glossy with clearly visible tertiary venation on both sides, while the leaflets of Le Testu 8407 are smaller (5 – 12 × 2 – 4 cm) in size, and less glossy with less clear tertiary venation. Additional fertile collections are needed to determine if Le Testu 2290 and 8407 represent one or two different taxa.

The 14 collections cited as Gilbertiodendron ngouniense have always 2 pairs of leaflets, stipules with an early caducous linear part and a persistent reniform part (not seen in two of the collections) and if there is a gland near the petiolule at the edge of the leaflet, this is always a submarginal gland. There are no other known species of Gilbertiodendron with these three characters combined. However, the leaflets of the 14 cited specimens of G. ngouniense show similar variation as those of Le Testu 2290 and 8407. Because of these differences in leaflet characters, it is not certain that all 14 specimens represent G. ngouniense, and the distribution of this species needs to be confirmed through collection and study of additional flowering and fruiting specimens.

2. Gilbertiodendron maximum Burgt & Wieringa sp. nov. Type: Gabon, Ogooué-Maritime, 4 km on the road from Rabi to Divangui, 24 July 1992, J. J. Wieringa 1315 (holotype WAG! [WAG0070212, –218, –219, –307, –308], isotypes BR!, BRLU, BUC, C, E, EA, FHO, FR, G, IAGB, K!, LBV, LUA, MA, MO, MPU, PE, PH, PRE, RSA, UC, US).

http://www.ipni.org/urn:lsid:ipni.org:names:77146134-1

Tree, to 45 m tall. Trunk to 140 cm diam. Twigs glabrescent to glabrous. Stipules in pairs, free; caducous, flat, fan-shaped, margin dentate, 4 – 13 × 3 – 11 mm, glabrous. Leaves paripinnate, to 38 × 29 cm; petiole 8 – 23 mm long, 2 – 4 mm diam., glabrescent or glabrous; leaf rachis 4 – 15 cm long, glabrous, stipels absent; petiolules 6 – 18 mm long, glabrous. Leaflets coriaceous, opposite, lower and middle pairs (sub-) opposite, 2 – 3 pairs, elliptic to obovate, 6 – 23 × 3 – 10 cm; smooth, somewhat glossy and glabrous both sides, lower surface same colour, midrib glabrous both sides, prominent below; 5 – 8 pairs of secondary veins; leaflet base cuneate to obtuse, sometimes slightly oblique; apex acute to obtuse. Glands 0 (– 1) per leaflet, at the proximal margin near the apex and at the distal margin near the petiolule. Inflorescence unknown; infructescences axillary or terminal, to 12 cm long, densely puberulous, hairs to 0.2 mm long. Flowers unknown. Fruits oblong-rectangular, brown, dull, glabrous, 1 – 6-seeded, 22 – 36 × 11 – 14 cm, valve 4 mm thick, beak 1 – 5 mm long, sutures not winged; 2 – 2.5 longitudinal ridges running from the base to the apex, parallel to and at 0.5 – 7 cm distance to the upper suture. Fig. 2; Map 4.

Fig. 2

Gilbertiodendron maximum. A leaf; B leaflet lower surface; C section of branch with two leaves (mostly removed) and stipules; D fruit. A, B, D from Wieringa 1315 (WAG), C from Valkenburg 2982 (WAG). drawn by xander van der burgt.

Map 4

Distribution of Gilbertiodendron maximum.

recognition. Gilbertiodendron maximum resembles G. ogoouense. The stipules of G. maximum are fan-shaped, not reniform as in G. ogoouense. The size of the leaflets of G. maximum is up to 23 × 10 cm; the size of the leaflets of G. ogoouense is up to 15 × 5 cm. The petiolule is 6 – 18 mm long; not 2 – 5 mm long. The size of the fruits is 22 – 36 × 11 – 14 cm, not 8 – 18 × 4 – 8 cm.

distribution. Gilbertiodendron maximum is endemic to the Ogooué-Maritime province in Gabon (Map 4).

specimens examined. gabon. Ogooué-Maritime, road from Rabi to Divangui, fr., 12 July 1998, Breteler 14400 (WAG); Ogooué-Maritime, Mt Igoumbi southern ascent, fr., 13 April 2005, Valkenburg 2982 (WAG); Ogooué-Maritime, 4 km on the road from Rabi to Divangui, fr., 24 July 1992, Wieringa 1315 (holotype WAG!, isotypes BR!, BRLU, BUC, C, E, EA, FHO, FR, G, IAGB, K!, LBV, LUA, MA, MO, MPU, PE, PH, PRE, RSA, UC, US).

habitat. Gilbertiodendron maximum occurs in evergreen rain forest on well-drained soil, at 0 – 200 m asl.

conservation status. Gilbertiodendron maximum is assessed here according to IUCN criteria as Critically Endangered B1ab(i,iii,v) (Table 1). The three localities where the species occurs are located in an area subject to logging, and are therefore considered to be one location (IUCN 2014), although it is not certain that the three localities are within the same logging concession.

etymology. The species epithet of Gilbertiodendron maximum refers to the large size of the trees from which the three known collections were made (61, 120 and 140 cm dbh), and the up to 18 mm long petiolules.

notes. The flowers of Gilbertiodendron maximum are unknown; a flowering collection would be most welcome. However, collections of the new species can be named without doubt if there are only leaves and fruits. G. maximum can be recognised by its large petiolules, 6 – 18 mm long, which is much longer than those of the other species of Gilbertiodendron (Table 2; Aubréville 1968, 1970). A phylogenetic study by Estrella et al. (2014) places the type of G. maximum (Wieringa 1315) in the G. ogoouense species complex. G. maximum is the ninth narrow endemic described from the greater Rabi area (Wieringa & Mackinder 2012). Of these 9 endemics, 5 belong to the legume tribe Detarieae, which is a very interesting phenomenon. It seems this area constitutes a local area of endemism for this group of ectomycorrhizal trees, while for most other plants it did not develop in such a way.

3. Gilbertiodendron ogoouense (Pellegr.) J. Léonard (1952a: 191; 1954: 61); Léonard (1957: 238); Aubréville (1968: 220); Aubréville (1970: 204 – 206).

Macrolobium ogoouense Pellegr. (Pellegrin 1941: 506; 1949: 51). Syntypes: Le Testu 5071, 6368, 8369, 8407. Lectotype chosen by J. Léonard (1952a: 189): Gabon, Haute Ngounyé, Ndenga, 1 Nov. 1926, G. M. P. C. Le Testu 6368 (lectotype P! [P00391243], isolectotypes BM!, BR!, K!, LISC!, MA!, P!, WAG!) [In the present study, the syntype Le Testu 5071 is included in Gilbertiodendron quinquejugum Burgt and the syntype Le Testu 8407 is included in G. ngouniense (Pellegr.) J. Léonard.].

Tree, to 39 m tall. Trunk straight, cylindrical, to 137 cm diam. Bark light yellowish-brown, exfoliating in small and thin papery flakes. Twigs glabrescent to glabrous. Stipules in pairs, free; reniform part persistent, flat, 8 – 22 × 6 – 16 mm, glabrous; lanceolate part of stipule not seen. Leaves paripinnate, to 18 × 15 cm; petiole 3 – 8 (– 13) mm long, 2 – 3 mm diam., puberulent to glabrous, hairs to 0.2 mm long; leaf rachis 2 – 7 (– 12) cm long, to 20 cm long on leaves of juvenile trees, glabrous, stipels absent; petiolules 2 – 5 mm long, puberulent to glabrous, hairs to 0.2 mm long. Leaflets papery, opposite, (2 –) 3 pairs, to 4 pairs on leaves of juvenile trees, elliptic to obovate, 5 – 12 (– 15) × 2 – 4 (– 5) cm; smooth, somewhat glossy and glabrous both sides, lower surface same colour or slightly lighter, midrib glabrous both sides, prominent below; 7 – 9 pairs of secondary veins; leaflet base cuneate to obtuse; apex acuminate and mucronate, acumen 0.5 – 1.5 cm long. Glands 0 – 1 (– 2) per leaflet, at the proximal margin 15 – 23 mm from the apex and at or close to the distal margin 3 – 9 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 7 (– 16) cm long, puberulous, hairs to 0.2 mm long, internodes 4 – 12 (– 18) mm long, lateral axes to 5 cm long, 10 – 12 flowers per cm. Flowers fragrant, floral bract inserted at base of pedicel, caducous, ovate, 2 – 3 × 1.5 – 2 mm, puberulous on both sides, hairs to 0.1 mm long, centre inside glabrous; pedicel 6 – 11 mm long, puberulous, light-coloured hairs to 0.2 mm long (on specimens from Cameroon mixed with sparse dark brown hairs to 0.3 mm long); bracteoles 2, elliptic, light green, 5 – 7 × 4 – 5 mm, puberulous outside, light-coloured hairs to 0.1 mm long, glabrous inside, a few hairs to 0.2 mm long near margin; receptacle 1 mm high, 2 mm diam. at top, glabrous or with a few hairs outside, mainly at adaxial and abaxial side; sepals 5, white, glabrous, narrowly triangular, 2 – 4 × 1 – 1.5 mm, apex acute; petals 5, white, glabrous, alternate to sepals; adaxial petal claw 2 – 5 mm long, blade bilobed, 4 – 9 mm high × 6 – 18 mm wide; the other 4 petals 2 – 3 × 0.7 – 1 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 8 – 21 mm long; anthers glabrous, 1.5 – 2 mm long; 6 staminodes, filiform, to c. 0.5 mm long, inserted on a staminodal tube c. 0.6 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 3 × 1.5 × 0.5 mm, 4 – 5 ovules, margins densely hirsute, hairs dark brown, to 0.8 mm long, sides glabrous; stipe 1 mm long; style 7 – 19 mm long, lower part hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 1 – 4-seeded, 8 – 18 × 4 – 8 cm, valve 3 mm thick, beak 1 – 3 mm long, sutures not winged; 2 – 3.5 longitudinal ridges running from the base to the apex, parallel to and at 0.5 – 3.5 cm distance to the upper suture. Seedlings: hypocotyl 5 – 7 cm, epicotyl 10 – 15 cm long; first two leaves opposite, petiole and rachis 1.7 – 2.5 cm long, petiolules 1 mm long, 1 pair of leaflets 9 – 12 × 3 – 4 cm (in reality 2 pairs of leaflets; lowest pair reduced to < 3 mm long). Figs 3, 4, 5; Map 1, 5.

Fig. 3

Gilbertiodendron ogoouense. A flower; B inflorescence. A – B from: Burgt 775. photos: xander van der burgt.

Fig. 4

Gilbertiodendron ogoouense flower. From Burgt 775. drawn by margaret tebbs.

Fig. 5

Gilbertiodendron ogoouense. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel. A – C from Breteler 15359 (WAG). drawn by margaret tebbs.

Map 5

Distribution of Gilbertiodendron ogoouense.

distribution. Gilbertiodendron ogoouense occurs in Cameroon, Equatorial Guinea, Gabon and Congo (Brazzaville) (Map 5). In Cameroon, the species occurs close to the Nigerian border, but is not mentioned in the book Trees of Nigeria by Keay (1989).

specimens examined. cameroon. Korup National Park, P plot, subplot 6F, fr., 27 Aug. 2004, Burgt 696 (BR, G, K, MO, P, SCA, WAG, YA); same loc., subplot 26I, fl., 28 Sept. 2004, Burgt 726 (SCA, WAG, YA); same loc., subplot 6F, fl., 13 Oct. 2005, Burgt 775 (BR, G, K, MO, P, SCA, WAG, YA); same loc., subplot 8F, sterile, 18 Nov. 2005, Burgt 799 (BR, G, K, MO, P, SCA, WAG, YA); same loc., subplot 6F, fl. & fr., 13 Dec. 2005, Burgt 819 (BR, G, K, MO, P, SCA, WAG, YA); near Bella (45 km NE of Kribi), fr., 26 Jan. 1962, Letouzey 4186 (P, YA); at 1 km of reserve Ngoandou, subdivision Mfou, fl., 10 Sept. 1953, Mpom 44 (SRFK 1876) (P, YA); Korup Reserve, sterile, March 1979, Thomas 591 (K); Meme Division, 10 km W of Banga, near Mukete Plantation, sterile, 30 Oct. 1985, Thomas 4873 (MO, YA); steep hillside S of Esukutang village, sterile, 25 May 1988, Thomas 7905 (MO). equatorial guinea. Monte Alén, fl., 4 Nov., 1998, Ngomo 555 (BRLU). gabon. Ogooué-Maritime, Toucan, fl., 11 Oct. 2002, Bourobou 978 (WAG); Ogooué-Maritime, Rabi Kounga, fl., 29 Oct. 1991, Breteler 10213 (WAG); same loc., sterile, 31 Oct. 1991, Breteler 10258 (WAG); between Rabi-Kounga and Yeno, fr., 15 May 1992, Breteler 11450 (LBV, WAG); same loc, fr., 18 May 1992, Breteler 11524 (LBV, WAG); Ogooué-Lolo, Bambidie, about 30 km E of Lastoursville, fl., 5 Nov. 1999, Breteler 15359 (LBV, WAG); Ogooué-Maritime, Rabi, sterile, 4 March 2007, Choo 794 (MO); Bambidie, route B3, sterile, 13 Aug. 1996, Dibata 1208 (WAG); Haute Ngounyé, Ndenga, fl., 1 Nov. 1926, Le Testu 6368 (lectotype P!, isolectotypes BM!, BR!, K!, LISC!, MA!, P!, WAG!); Ogooué-Lolo, région de Lastoursville, Ivicou, fl., 21 Sept. 1930, Le Testu 8369 (BM, BR, LISC, MO, NY, P, S); Loango National Park, à 1300 m du débarcadère de Rabi village, fr., 29 Aug. 2004, Mouandza Mbembo 248 (WAG); Rabi-Kounga, fl., 21 Oct. 1991, Schoenmaker 70 (LBV, WAG); Rabi-Kounga, N of airstrip, in 1-ha plot, sterile, 25 July 1992, Wieringa 1316 (LBV, WAG); Rabi, 1 km SE of Shell camp, fl., 24 Sept. 1994, Wieringa 2777 (BR, G, K, LBV, MA, MPU, P, WAG). congo (brazzaville). Massif du Chaillu, Lefoutou, sterile, 25 April 2013, Cheek 17030 (IEC, K); Lékoumou Préfecture, NW of Zanaga, 13 km N of Lefoutou, sterile, 31 May 2010, M’Boungou 225 (IEC); same loc., sterile, 30 May 2010, Mpandzou 44 (IEC, K, MO, WAG); Chaillu, Divenié, on the Bibaka, sterile, July 1983, Sita 4861 (BR).

habitat. Gilbertiodendron ogoouense occurs in evergreen rain forest on well-drained soil and periodically inundated soil; at 0 – 700 m asl.

conservation status. Gilbertiodendron ogoouense is assessed here according to IUCN criteria as Least Concern (Table 1).

ecology. In Korup National Park in Cameroon, trees of Gilbertiodendron ogoouense are growing in groups. Six such groups were mapped; 5 in the “P plot” (Map 2 in Burgt et al. 2012) and one in the adjacent “NW plot” (Map 1). The groups consist of 12, 13, 13, 16, 17 and 29 trees over 10 cm dbh. The six groups have diameters of c. 100 – 200 m and are positioned at distances of c. 100 – 700 m to each other. More groups were found outside the plots, but these were not mapped. Within the six groups, G. ogoouense is co-dominant with Microberlinia bisulcata A. Chev., Tetraberlinia bifoliolata (Harms) Hauman and T. korupensis Wieringa; and to a lesser extent with several other tree species from the Caesalpinioideae subfamily. Tree species belonging to other families are also present. Within the area occupied by the six groups, about 20% – 30% of the trees over 50 cm dbh belong to the species G. ogoouense.

notes. Macrolobium ogoouense was described with 4 syntypes: Le Testu 5071, 6368, 8369 and 8407. One of the four syntypes, Le Testu 6368, was chosen to be the lectotype by J. Léonard (1952a: 189). A second syntype, Le Testu 8369, is similar to this lectotype. The third syntype, Le Testu 8407, is presently included in G. ngouniense and the fourth syntype, Le Testu 5071, is included in G. quinquejugum. The reasons for this are given in the notes section of the descriptions of these species.

Most of the material previously named to Gilbertiodendron ogoouense (for example in Sosef et al. (2006)) is renamed in this manuscript to newly described species. The 12 flowering collections that remain in G. ogoouense are still somewhat variable and can be morphologically divided into 3 groups of collections, which are also geographically separated from each other (Table 3). However, the differentiating characters of these 3 groups of collections are small and somewhat inconsistent; it is therefore not certain if these 3 groups represent 1, 2 or perhaps 3 different taxa. For example, the maximum length of the inflorescence (Table 3) may not be a differentiating character. Of the four collections from western Gabon, three have elongated inflorescences while the fourth, otherwise well-matching collection Breteler 10213, has congested inflorescences. The BM sheet of Le Testu 9612 (G. sulfureum) has elongated inflorescences to 19 cm long but all other sheets of this collection have congested inflorescences.

Table 3. Comparison of the characters of the 12 flowering collections of Gilbertiodendron ogoouense. Pod measurements are from additional collections from the same areas; group 1: Burgt 696, 819; group 2: Breteler 11450; Mouandza 248.

Of the 12 flowering collections in Table 3, three have been included in a phylogenetic study (Estrella et al. 2014): Burgt 775, Schoenmaker 70 and Wieringa 2777. That study indicates that Burgt 775 may not be conspecific with the other two collections. The study of Estrella et al. (2014) also indicates that Breteler 10258 (a sterile specimen from a sapling) and Breteler 11524 (a fruiting specimen) together represent a separate species. However, Breteler 11524 does not show any clear morphological differences with the other specimens cited under Gilbertiodendron ogoouense. Since the specimens of group 3 in Table 3 (the two type specimens and Breteler 15359) were not sampled by Estrella et al. (2014), it is at the moment difficult to decide how many different taxa are present within the 12 flowering collections of G. ogoouense.

4. Gilbertiodendron ecoukense (Pellegr.) Burgt, comb. nov.

http://www.ipni.org/urn:lsid:ipni.org:names:77146135-1

Macrolobium ecoukense Pellegr., Pellegrin, Bull. Soc. Bot. France 88: 507 (1941) as “Macrolobium ecoueense Pellegr.”. Type: Gabon, région entre Ogooué et Cameroun, Ecouc, Ecoue, Ecoué, Ecouk, 29 June 1934, G. M. P. C. Le Testu 9622 (holotype P! [P00391245], isotypes AAH!, B!, BM!, BR!, HBG!, K!, LISC!, WAG!); Pellegrin (1949: 52); Index Kewensis (1953: 148); Léonard (1954: 61); Léonard (1957: 238); Aubréville (1968: 221); as “Macrolobium ecoucense Pellegr.”: Pellegrin (1949: 52); Aubréville (1968: 221; 1970: 204).

Tree, to c. 40 m tall. Trunk straight, cylindrical, to c. 100 cm diam. Bark greyish light brown, exfoliating in small woody flakes. Twigs glabrescent or glabrous; twigs of juvenile trees puberulent to glabrescent, hairs 0.2 mm long. Stipules in pairs, free; reniform part absent, lanceolate part of stipule only seen on leaves of juvenile trees, early caducous, narrowly triangular, 4 – 6 × 0.8 mm, parallel-veined, ciliate, glabrous above, puberulent below, hairs 0.2 mm long. Leaves paripinnate, to 22 × 16 cm; petiole 4 – 8 mm long, 1.5 – 3 mm diam., glabrescent to glabrous; leaf rachis 2 – 11 (– 15) cm long, glabrescent to glabrous, stipels absent; petiolules 3 – 6 mm long, glabrescent to glabrous. Leaflets coriaceous, opposite, 2 – 4 (– 5) pairs, elliptic, 5 – 12 (– 17) × 2 – 4 (– 7) cm (leaflets on juvenile trees to 25 × 8 cm); smooth, somewhat glossy and glabrous both sides, lower surface same colour or slightly lighter, midrib glabrous on both sides, prominent below, midrib of juvenile trees puberulent to glabrescent below, hairs 0.2 mm long; 6 – 9 pairs of secondary veins; leaflet base cuneate to obtuse, slightly oblique; apex acuminate and mucronate, acumen 0.3 – 1 cm long. Glands 0 – 1 per leaflet (to 4 glands per leaflet on juvenile trees), 0 – 1 marginal glands at the proximal margin 5 – 10 mm from the apex and 0 – 1 submarginal glands at the distal margin 2 – 7 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 14 cm long, densely puberulous, hairs to 0.3 mm long, internodes 5 – 15 mm long; lateral axes to 6 (–10) cm long, 6 – 12 flowers per cm. Flowers fragrant, floral bract inserted at base of pedicel, caducous, ovate, 3 – 5 × 2 – 4 mm, densely puberulous on both sides, hairs to 0.2 mm long, centre inside glabrous; pedicel 3 – 6 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with dark brown hairs to 0.3 mm long; bracteoles 2, elliptic, white, 5 – 7 × 4 – 5 mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.2 mm long; puberulous inside, centre inside glabrous; receptacle 1 mm high, 2 mm diam. at top, glabrous apart from two patches of hairs outside, at adaxial and abaxial side; sepals 5, white, narrowly triangular, 3 – 4 × 1.5 mm, apex acute, glabrous, sometimes a few hairs on lower margins; petals 5, alternate to sepals, white, glabrous; adaxial petal claw 5 – 7 mm long, blade bilobed, 6 mm high × 12 mm wide; the other 4 petals 2.5 × 1 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 10 – 12 mm long; anthers light yellow, glabrous, 2 mm long; 6 staminodes, filiform, to c. 0.5 mm long, inserted on a staminodal tube c. 1 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 4 × 2 × 0.5 mm, 4 – 5 ovules, margins densely hirsute, hairs to 0.8 mm long, sides glabrous; stipe 1 mm long; style 9 – 11 mm long, lower part sparsely hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 1 – 3-seeded, 14 – 19 × 5 – 7 cm, valve 3 mm thick, beak 2 – 5 mm long, sutures not winged; 1.5 – 3 longitudinal ridges running from the base to the apex, parallel to and at 0.5 – 2.5 cm distance to the upper suture. Seeds brown, c. 34 × 30 × 7 mm. Seedlings: hypocotyl 4 – 5 cm long, epicotyl 10 – 13 cm long; first two leaves opposite, petiole and rachis 2 – 3 cm long, petiolules 2 mm long, 1 pair of leaflets 11 – 14 × 3 – 4.5 cm (in reality 2 pairs of leaflets, lowest pair usually reduced to < 3 mm long, sometimes up to 3 × 1 cm). Figs 6, 7; Map 6.

Fig. 6

Gilbertiodendron ecoukense, the tree from which M'Boungou 387 was collected, in Congo (Brazzaville). A the tree on 1 June 2010, the day the collection was made; B the same tree on 26 February 2012. Five of the six trees present here had been logged a few months earlier by a logging company. photos: xander van der burgt.

Fig. 7

Gilbertiodendron ecoukense. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel; D fruit. A – C from M’Boungou 387; D from McPherson 16633. drawn by margaret tebbs.

Map 6

Distribution of Gilbertiodendron ecoukense.

distribution. Gilbertiodendron ecoukense occurs in Cameroon, Equatorial Guinea, Gabon, Congo (Brazzaville) and western Congo (Kinshasa) (Map 6). Considering the currently known distribution, it is likely that G. ecoukense also occurs in Angola (Cabinda).

specimens examined. cameroon. South Region, valley of Ntem at Oveng, near Nyabessan, 60 km E of Campo, sterile, 9 April 1970, Letouzey 10323 (P, WAG, YA); same loc., fl., 9 April 1970, Letouzey 10323 bis (P, WAG, YA). equatorial guinea. Monte Alén National Park, in the SE, S of Rio Laña, near cabaña Ecofac de Misergue, fr., 14 July 2002, Senterre 3329 (BRLU). gabon. Woleu-Ntem, région entre Ogooué et Cameroun, Ecouc, Ecoue, Ecoué, Ecouk, fl., 29 June 1934, Le Testu 9622 (holotype P!, isotypes AAH!, B!, BM!, BR!, HBG!, K!, LISC!, WAG!); Ogooué-Lolo, E of Lastoursville, near Bambidie, C.E.B. chantier, fr., 19 Sept 1996, McPherson 16633 (WAG); Ogooué-Maritime, Rabi, sterile, 25 March 2014, Nguema Ekomo 2809 (WAG); same loc., sterile, 25 March 2014, Nguema Ekomo 2810 (WAG); same loc., sterile, 25 March 2014, Nguema Ekomo 2811 (WAG); Woleu-Ntem, Crystal Mts, 18650 m on transect G, fl., 28 March 2001, Nguema Miyono 1782 (MO, WAG); same loc., 24850 m on transect G, fr., 30 March 2001, Nguema Miyono 1798 (LBV, MO, WAG); Ogooué-Lolo, c. 30 km ENE of Lastoursville, c. 2 km N of Bambidie forestry camp, fr., 22 Jan. 2008, Wieringa 6070 (LBV, WAG); Estuaire, Crystal Mts NP, left bank of Mbei R. opposite Kinguélé, sterile, 25 March 2013, Wieringa 7723 (WAG). congo (brazzaville). Lékoumou Préfecture, NW of Zanaga, 17 km N of Lefoutou, sterile, 14 Oct. 2009, Cheek 15856 (IEC, K); same loc., sterile, 27 March 2009, Koubemba 8 (IEC, K, P, WAG); Kouilou Préfecture, Mayombe, M'Banga, fr., 9 March 1970, Mabiala 776 (P); same loc., fr., 29 June 1971, Mabiala 997 (P); Lékoumou Préfecture, NW of Zanaga, 17 km N of Lefoutou, fr., 26 May 2010, M'Boungou 144 (IEC, K, MO, P, WAG); same loc., fl., 1 June 2010, M'Boungou 387 (BR, G, IEC, K, LBV, LISC, MA, MO, P, PRE, S, SING, WAG, US); 13 km N of Lefoutou, sterile, 30 May 2010, Mpandzou 45 (IEC, K). congo (kinshasa). Ineac Luki Mayumbe, Bas-Congo, fl., 1959, Matton 44 (BR, WAG).

habitat. Gilbertiodendron ecoukense occurs in evergreen rain forest on well-drained soil; at 0 – 900 m asl.

conservation status. Gilbertiodendron ecoukense is assessed here according to IUCN criteria as Least Concern (Table 1).

etymology. The species epithet of Gilbertiodendron ecoukense refers to a village in Gabon. The name of the village is handwritten in four different ways on the labels of the type Le Testu 9622: Ecouc, Ecoue, Ecoué and Ecouk; some of this handwriting may have been added after the publication of the basionym. Pellegrin published Macrolobium ecoueense Pellegr. in 1941. However, eight years later he used the spelling Macrolobium ecoukense Pellegrin; and remarked “= Macrolobium ecoucense Pellegr.” (Pellegrin 1949); spelling the species epithet in a second and a third way. In that publication the author preferred the spelling M. ecoukense and apparently considered both other ways of spelling to be incorrect. Léonard (1954) also used the name M. ecoukense when incorporating the species into G. ogoouense; and considered the spelling M. ecoueense an error. Ecoue, Ecoué and M. ecoueense are likely spelling errors, rejected not only by Pellegrin (1949) and Léonard (1954), but also by Aubréville (1968, 1970) and Index Kewensis (1953: p. 148). The name G. ecoukense is used here for the new combination, because this spelling is in accordance with the Code and because this is the most commonly used way of spelling.

notes. A phylogenetic study by Estrella et al. (2014) places one of the flowering collections of Gilbertiodendron ecoukense (M’Boungou 387) in the G. ogoouense species complex, thereby confirming the results of the morphological study. This study also suggests that M’Boungou 144 and Wieringa 6070 represent G. ecoukense, already placed in this species by their morphological characters.

The persistent, reniform stipules so characteristic of most other species in the Gilbertiodendron ogoouense species complex, are absent in G. ecoukense (as well as in G. klainei). No reniform stipules were seen on the numerous duplicates of the flowering collections Le Testu 9622 and M’Boungou 387. The juvenile material collected as M’Boungou 144 at the site of M’Boungou 387 has small, early caducous, lanceolate stipules without a reniform part. This indicates that the reniform part of the stipule in G. ecoukense is not early caducous, but absent, because in the other species in the complex (except G. klainei) the reniform part of the stipule is persistent, while the lanceolate part is caducous.

Gilbertiodendron ecoukense can also be recognised by its coriaceous leaflets. Those species in the G. ogoouense species complex which might be confused with G. ecoukense have less coriaceous leaflets. Sterile material of G. ecoukense is difficult to distinguish from G. preussii (Harms) J. Léonard. Both species have 3 – 5 pairs of leaflets of similar size and shape, early caducous stipules and long petiolules. However, fertile material is easy to distinguish: G. preussii has an elongated inflorescence, with pedicels of 8 – 20 mm long and bracteoles 7 – 13 mm long; as well as pods 15 – 35 × 5 – 8 cm with only a single longitudinal ridge.

Gilbertiodendron ecoukense may be more common than the distribution map suggests. Because there are no characteristic stipules as in most of the other species in the complex, the species presumably is less often collected sterile compared to these other species, and if collected sterile the collection is less likely to be named correctly.

5. Gilbertiodendron minkebense Burgt & Estrella, sp. nov. Type: Gabon, Woleu-Ntem, Minkébé region, Sing valley, 5 km from camp site, 13 April 1990, A. Moungazi in Minkébé series AM 72 (holotype WAG! [WAG0164298, WAG0164299]).

http://www.ipni.org/urn:lsid:ipni.org:names:77146136-1

Tree, to 25 m tall. Trunk to 50 cm diam. Twigs sparsely puberulent to glabrous, erect light-coloured hairs to 0.1 mm long. Stipules in pairs, free; reniform part persistent, flat, 10 – 20 × 6 – 12 mm; sometimes to 32 × 22 × 10 mm and then a pair of stipules strongly inrolled towards each other; glabrous both sides; lanceolate part of stipule not seen. Leaves paripinnate, to 32 × 22 cm, on juvenile trees to 50 × 35 cm; petiole 5 – 9 mm long, 3 – 4 mm diam., sparsely puberulent to glabrous; leaf rachis 3 – 20 cm long, on juvenile trees to 40 cm long, sparsely puberulent to glabrous, stipels absent; apex of rachis sometimes with a glandular-like structure; petiolules 2 – 5 mm long, sparsely puberulent to glabrous. Leaflets coriaceous, opposite, 2 – 5 pairs, upper pair obovate, other pairs elliptic, (5 –) 7 – 14 (– 16) × (2 –) 3 – 5 (– 8) cm (leaflets of juvenile trees to 21 × 9 cm), smooth and glabrous both sides, above somewhat glossy, below dull and same colour or slightly darker (on dried specimens); midrib prominent and glabrous above, less prominent and glabrous below; 7 – 9 pairs of secondary veins; leaflet base cuneate to obtuse, oblique; apex acuminate and mucronate, acumen 0.5 – 1.5 cm long. Glands 1 – 2 per leaflet, at the proximal margin 7 – 22 mm from the apex and at the distal margin 5 – 8 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 8 cm long, densely puberulous, hairs to 0.2 mm long, internodes 6 – 9 mm long, lateral axes to 4 cm long, with 6 – 8 flowers per cm. Flowers: floral bract inserted at base of pedicel, caducous, ovate, 3 – 4 × 2 mm, densely puberulous both sides, hairs to 0.1 mm long, centre inside glabrous; pedicel 7 – 23 mm long, densely puberulous, light-coloured hairs to 0.1 mm long; bracteoles 2, elliptic to lanceolate, 7 – 11 × 4 – 6 mm, puberulous outside, light-coloured hairs to 0.1 mm long, inside puberulous along margin, centre inside glabrous; receptacle 1.5 mm high, 2.5 mm diam. at top, glabrous or with a patch of short hairs at base outside, at abaxial side; sepals 5, glabrous, narrowly triangular, 4 – 5 × 1 – 1.5 mm, apex acute; petals 5, alternate to sepals, glabrous, adaxial petal (not fully developed) claw 5 mm long, blade bilobed, 7 mm high × 12 mm wide; the other 4 petals 4 – 5 × 0.8 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments glabrous, 13 – 18 mm long; anthers glabrous, 2.5 mm long; 6 staminodes, filiform, to c. 1 mm long, inserted on a staminodal tube c. 1 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary 3 × 1.5 × 0.5 mm, 3 – 4 ovules, margins densely hirsute, hairs to 0.8 mm long, sides glabrous; stipe 1 mm long; style 16 mm long, lower part sparsely hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 1 – 4-seeded, 10 – 15 × 4 – 5 cm, valve 3 mm thick, beak 1 – 3 mm long, sutures not winged; 2.5 – 3 longitudinal ridges running from the base to the apex, parallel to and at 0 – 2.8 cm distance to the upper suture. Fig. 8; Map 7.

Fig. 8

Gilbertiodendron minkebense. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel. A – C from Moungazi in Minkébé series AM 72 (WAG). drawn by margaret tebbs.

Map 7

Distribution of Gilbertiodendron minkebense.

recognition. Gilbertiodendron minkebense is related to G. ogoouense. The leaves have a rachis of 3 – 20 cm long, and 2 – 5 pairs of leaflets. G. ogoouense has a rachis of only 2 – 7 (– 12) cm long, and (2 –) 3 pairs of leaflets. The pedicel of G. minkebense is 7 – 23 mm long and the size of the bracteoles is 7 – 11 × 4 – 6 mm. The pedicel of G. ogoouense is 6 – 11 mm long, and the size of the bracteoles is 5 – 7 × 4 – 5 mm.

distribution. Gilbertiodendron minkebense occurs in Gabon and in Congo (Brazzaville) (Map 7).

specimens examined. gabon. Woleu-Ntem, Sud-Est du Parc National de Minkébé, rivière Sing, sterile, 12 Aug. 2009, Dauby 2040 (BRLU); Minkébé region, Sing R. valley, 214 m on transect B, fr., 19 Feb. 1990, Dibata in Minkébé series E 18 (WAG); same loc., 2147 m on transect A, sterile, 8 March 1990, Dibata in Minkébé series C 367 (WAG); same loc., 5 km from camp site, fl., 13 April 1990, Moungazi in Minkébé series AM 72 (holotype WAG!); same loc., 192 m on transect A, sterile, 2 Feb. 1990, Wilks in Minkébé series C 33 (WAG); same loc., 2200 m on transect A, sterile, 22 May 1990, Wilks in Minkébé series C 439A (WAG). congo (brazzaville). Makoua region, at 10 km on the road to Etoumbi, 12 June 1961, fl., Descoings 7334 (IEC, K, MPU, P, WAG); Région de Fort Rousset, piste d'Assoko à Ekoungounou, sur la route d'Ewo, fr., 26 July 1961, Descoings 8591 (IEC, MPU, P); Parc National d'Odzala, Mboko, sur la Lékémé, fr., 6 Jan. 1994, Dowsett-Lemaire 1601 (BR); same loc., fl., 1 June 1994, Dowsett-Lemaire 1790 (BR); Parc National d'Odzala, sterile, 17 June 1995, Kouka 131 (BRLU, K); Parc National d'Odzala, près du Camp Mboko, vallée de la Leboli, fr., 9 Feb. 1994, Lisowski C943 (BRLU); Fort-Rousset, fr., 15 Oct. 1951, Trochain 8426 (IEC, P).

habitat. Gilbertiodendron minkebense occurs in evergreen rain forest, swamp forest and riverine G. dewevrei forest, at 200 – 900 m asl.

conservation status. Gilbertiodendron minkebense is assessed here according to IUCN criteria as Vulnerable B1ab(i,iii,v) (Table 1).

etymology. The species epithet of Gilbertiodendron minkebense refers to the Minkébé National Park in Gabon, where five collections including the type were made.

notes. The differences between Gilbertiodendron minkebense and G. ebo are given in the recognition and notes of the description of G. ebo. All collections of G. minkebense have flat stipules except one: Descoings 8591 has stipules resembling those of G. ebo, with pairs of stipules strongly inrolled towards each other (the IEC and P sheets; the MPU sheet has no stipules). Descoings 8591 is included in G. minkebense because the specimen shows several characteristics of this species: the leaflet midrib is more prominent above, the leaflet is oblique, the petiolule is 5 mm long or less, and the fruit is less than 15 cm long.

6. Gilbertiodendron ebo Burgt & Mackinder, sp. nov. Type: Cameroon, Littoral Region, Ebo Proposed National Park, path from Iboti village to Bekob Camp, at c. 7 km from Iboti and at 5.7 km from Bekob, 26 Nov. 2013, X. M. van der Burgt & E. Ngansop 1677 (holotype K! [K000745993, K000745994, K000745995], isotypes BR!, G!, MO!, P!, SCA!, WAG!, YA!).

http://www.ipni.org/urn:lsid:ipni.org:names:77146137-1

Tree, to c. 33 m tall. Trunk to 69 cm diam. Twigs puberulent to glabrous, appressed reddish brown hairs to 0.2 mm long. Stipules in pairs, free; reniform part persistent, a pair of stipules strongly inrolled towards each other; 10 – 40 × 8 – 18 × 5 – 15 mm, both sides sparsely puberulent to glabrous, hairs to 0.1 mm long; lanceolate part of stipule early caducous, c. 8 × 2 mm. Leaves paripinnate, to 50 × 35 cm, on juvenile trees to 60 × 45 cm; petiole 6 – 20 mm long, 3 – 8 mm diam., sparsely puberulent, hairs to 0.3 mm long; leaf rachis (0 –) 9 – 34 cm long, on juvenile trees to 41 cm long, sparsely puberulent to glabrous, stipels absent, apex of rachis sometimes with a glandular-like structure; petiolules 5 – 11 mm long, sparsely puberulent to glabrous. Leaflets coriaceous, opposite, 1 – 6 pairs, upper pair obovate, other pairs elliptic, (7 –) 12 – 28 × (4 –) 5 – 10 cm, leaflets of juvenile trees to 33 × 13 cm; both sides smooth, dull to somewhat glossy and identical in colour, upper surface glabrous, lower surface sparsely puberulent to glabrous, hairs to 0.1 mm long; midrib glabrous above, prominent and sparsely puberulent below; 5 – 12 pairs of secondary veins; leaflet base obtuse to rounded, apex glandular, acute to acuminate, 1 – 15 mm long. Glands 0 – 3 per leaflet, at the proximal margin 0 – 40 mm from the apex and at the distal margin 3 – 15 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 17 cm long, densely puberulous, hairs to 0.2 mm long, internodes to 30 mm long; lateral axes to 10 cm long, 6 – 8 flowers per cm. Flowers: floral bract inserted at base of pedicel, caducous to persistent, broadly ovate, 4 × 4 mm, densely puberulous on both sides, upper part inside glabrous, dark brown hairs to 0.1 mm long; pedicel light green, 12 – 22 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.3 mm long; bracteoles 2, elliptic to lanceolate, light green to white outside, white inside, 12 – 16 × 7 – 8 mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.3 mm long; inside densely puberulous on upper part and near margin, centre glabrous; receptacle 3 mm high, 4 mm diam. at top, glabrous or with one or two patches of hairs outside, at adaxial and abaxial side; sepals 5, white, glabrous, sometimes a few hairs on margins, narrowly triangular, 10 – 13 × 2 – 3 mm, apex acute; petals 5, alternate to sepals, white, glabrous; adaxial petal claw 5 – 6 mm long, blade bilobed, 10 – 12 mm high × 18 – 24 mm wide; the other 4 petals 10 – 12 × 2 mm, apex acute, sometimes with a few hairs; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 22 – 26 mm long; anthers white to dark brown, glabrous, 4 mm long; 6 staminodes, filiform, to c. 4 mm long, inserted on a staminodal tube c. 1 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 5 × 2 × 0.5 mm, 7 – 8 ovules, margins densely hirsute, dark brown hairs to 0.8 mm long, sides glabrous; stipe 2 mm long; style white, 20 – 24 mm long, lower part sparsely hirsute, upper part glabrous; stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 2 – 7-seeded, 18 – 33 × 7 – 11 cm, valve 3 mm thick, beak 1 – 4 mm long, sutures not winged; 2.5 – 3.5 strong longitudinal ridges running from the base to the apex, parallel to and at 0.5 – 7 cm distance to the upper suture. Figs 9, 10; Map 8.

Fig. 9

A pair of stipules from a mature tree of Gilbertiodendron ebo (Burgt 1677). Each of the two stipules is c. 40 × 18 × 15 mm. photo: xander van der burgt.

Fig. 10

Gilbertiodendron ebo. A branch with two inflorescences (one mostly removed); B leaf with pair of stipules; C leaflet lower surface; D floral bract; flower buds with short and long pedicel; E fruit. A – D from Burgt 1677 (K); E from Burgt 1663 (K). drawn by margaret tebbs.

Map 8

Distribution of Gilbertiodendron ebo.

recognition. Gilbertiodendron ebo is related to G. minkebense. The reniform stipules (Fig. 9) are up to 40 × 18 × 15 mm and a pair of stipules is strongly inrolled towards each other (in G. minkebense the reniform stipules are usually flat and up to 20 × 12 mm, but sometimes to 32 × 22 × 10 mm with a pair of stipules strongly inrolled towards each other). Both sides of the leaflet of G. ebo are identical in colour (in G. minkebense the lower surface of dried leaflets is usually somewhat darker), the leaflet is not oblique (clearly oblique in G. minkebense), G. ebo has a leaflet midrib more prominent below (the midrib is more prominent above in G. minkebense). and the petiolule is 5 – 11 mm long (2 – 5 mm long in G. minkebense). The bracteoles are 12 – 16 mm long (instead of 7 – 11 mm long) and the number of ovules is 7 – 8 (instead of 3 – 4). The dimensions of the fruits of G. ebo are 18 – 33 × 7 – 11 cm, with 2 – 7 seeds (in G. minkebense the dimensions of the fruits are 10 – 15 × 4 – 5 cm, with 1 – 4 seeds).

distribution. Gilbertiodendron ebo is endemic to Cameroon (Map 8).

specimens examined. cameroon. Littoral Region, Ebo Proposed National Park, path from Iboti village to Bekob Camp, at c. 7.5 km from Iboti and at 5.3 km from Bekob, fl. + fr., 24 Nov. 2013, Burgt 1663 (BR, G, K, MO, P, SCA, WAG, YA); same loc., at c. 7 km from Iboti and at 5.7 km from Bekob, fl., 26 Nov. 2013, Burgt 1677 (holotype K!; isotypes BR!, G!, MO!, P!, SCA!, WAG!, YA!); South-West Region, Mungo R. Forest Reserve, just N of Bulutu, sterile, 30 Nov., 1999, Cheek 10190 (K, WAG); Southwest Region, 40 km N of Kumba, between Ekona and Boubaji, near Supé, sterile, 20 Aug. 1975, Letouzey 14349 (K, YA); same loc., sterile, 20 Aug. 1975, Letouzey 14350 (K, YA); Mungo R. Forest Reserve, Mahole, sterile, 24 Nov. 1999, Mackinder 207 (K, MO, WAG); Littoral Region, foot path from Iboti to Bekob camp in Ebo forest, fr., 12 March 2007, Wieringa 5922 (WAG); same loc., sterile, 12 March 2007, Wieringa 5923 (WAG); c. 50 km NW of Eséka, W of Yaoundé, on opposite of the Kelè-river, fl., 22 Nov. 1963, W. J. J. O. de Wilde 1306 (B, BR, K, MO, P, PRE, WAG, YA).

habitat. Gilbertiodendron ebo occurs in evergreen rain forest; at 200 – 800 m asl.

conservation status. Gilbertiodendron ebo is assessed here according to IUCN criteria as Endangered B1ab(i,iii,v) (Table 1).

etymology. The species epithet of Gilbertiodendron ebo refers to the Ebo Forest in Cameroon, where the type specimen was collected. The Ebo Forest is proposed to become a national park, because of its abundance in primate species and plant species.

notes. The type of Gilbertiodendron ebo, Burgt 1677, was collected from the tree from which Wieringa and Mackinder collected pods 6 years earlier (Wieringa 5923). The collection Burgt 1663 was collected from the tree beneath which Wieringa and Mackinder collected a sapling 6 years earlier (Wieringa 5922). These two trees are standing at 465 m distance to each other. They were revisited towards the end of November, because the only existing flowering collection was made 22 November 1963 (W. J. J. O. de Wilde 1306). Both trees were indeed flowering at the end of November 2013.

7. Gilbertiodendron newberyi Burgt, (Burgt et al. 2012: 52). Type: Cameroon, Southwest Region, Korup National Park, 12 Oct. 2005, X. M. van der Burgt 774 (holotype WAG! [WAG0204478], isotypes BR!, G!, K!, MO!, P!, SCA!, YA!).

Tree, to 51 m tall. Trunk straight, cylindrical, to 197 cm diam. Bark greyish brown, exfoliating in small woody flakes. Twigs sparsely puberulent to glabrescent, hairs to 0.2 mm long. Stipules in pairs, free, reniform part persistent, flat, 8 – 33 × 6 – 27 mm, sparsely puberulent to glabrescent both sides, hairs to 0.1 mm long; lanceolate part of stipule not seen. Leaves paripinnate, to 40 × 25 cm; petiole 4 – 10 mm long, 2 – 4 mm diam., puberulent, hairs to 0.1 mm long; leaf rachis 5 – 30 cm long, puberulent to glabrescent, hairs to 0.1 mm long, stipels absent; petiolules 2 – 4 mm long, puberulent to glabrescent, hairs to 0.1 mm long. Leaflets papery, opposite, 3 – 5 (– 6) pairs, elliptic, 4 – 20 × 2 – 6 cm, smooth and glabrous both sides; somewhat glossy above, below dull, same colour or slightly lighter; midrib puberulent to glabrous both sides, prominent below; 6 – 10 pairs of lateral veins; leaflet base cuneate to obtuse, sometimes slightly oblique, apex acuminate and mucronate, acumen 0.3 – 1 cm long. Glands 0 (– 1) per leaflet, at the proximal margin 8 – 15 mm from the apex and at the distal margin 3 – 6 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 8.5 cm long, dark brown hairs to 0.1 mm long, internodes 4 – 8 mm long, lateral axes to 5.5 cm long, 12 – 15 flowers per cm, puberulous. Inflorescence bracts in pairs at base of lateral axes, caducous, linear part 4.5 – 7 × 1 – 1.5 mm, auriculate part 2 × 2.5 mm. Flowers fragrant, floral bract inserted at base of pedicel, caducous, ovate to broadly ovate, 2 – 4 × 1.5 – 4 mm, puberulous on both sides, hairs to 0.1 mm long, centre inside sometimes glabrous; pedicel 7 – 15 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.2 mm long; bracteoles 2, elliptic, whitish light green, 5 – 8 × 4 – 6 mm, puberulous outside, light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.2 mm long; sparsely puberulous inside, centre inside glabrous; receptacle 1 – 1.5 mm high, 1.5 – 2 mm diam. at top, upper part glabrous, lower part with 4 patches of hairs, or a band of hairs of irregular width, hairs 0.2 mm long; sepals 5, white, glabrous, narrowly triangular, 3.5 – 5 × 1 mm, apex acute, abaxial sepal a little larger; petals 5, alternate to sepals, white, glabrous; adaxial petal claw 4 – 5 mm long, blade bilobed, 8 – 13 mm high × 10 – 19 mm wide; the other 4 petals narrowly triangular, 3.5 – 5 × 1 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 10 – 14 mm long; anthers glabrous, 2 – 2.5 mm long; 6 staminodes, filiform, to c. 1 mm long, inserted on a staminodal tube c. 0.5 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 3 × 1.5 × 0.5 mm, 5 – 6 ovules, margins densely hirsute, hairs brown, to 0.7 mm long, sides glabrous; stipe 0.7 mm long; style white, 10 – 14 mm long, lower part hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 1 – 3-seeded; 12 – 20 × 4.5 – 7 cm, valve 3 mm thick, beak 0 – 2 mm long, sutures not winged; 2 – 2.5 longitudinal ridges running from the base to the apex, parallel to and at 0.3 – 3 cm distance to the upper suture. Seedlings: hypocotyl 5 – 8 cm long, epicotyl 10 – 15 cm long; first two leaves opposite, petiole and rachis 2 – 4 cm long, petiolules 1 mm long, 1 – 2 pairs of leaflets 8 – 12 × 3 – 4 cm (in reality 2 – 3 pairs of leaflets, lowest pair reduced to < 3 mm long). Description adapted from Burgt et al. (2012). Fig. 11; Map 9.

Fig. 11

Gilbertiodendron newberyi. A branch with inflorescences; B leaf and pair of stipules (one replaced); C leaflet lower surface; D floral bract; flower buds with short and long pedicel; E fruit. A from Burgt 776 (WAG); B – E from Burgt 774 (K, WAG). drawn by xander van der burgt.

Map 9

Distribution of Gilbertiodendron newberyi.

distribution. Gilbertiodendron newberyi occurs in Cameroon, in the Southwest Region and the Littoral Region (Map 9).

specimens examined. cameroon. Littoral Region, SE of Yingui, Ebo Forest, path from Iboti village to Bekob Camp, at c. 3 km from Iboti, fl., 24 Nov. 2013, Burgt 1661 (K, WAG, YA); Southwest Region, Korup National Park, P Plot, subplot 15B, tree number P3711, fl. and fr. 12 Oct. 2005, Burgt 774 (holotype WAG!, isotypes BR!, G!, K!, MO!, P!, SCA!, YA!); subplot 12B, tree number P3433, fl. 14 Oct. 2005, Burgt & Eyakwe 776 (BR, G, K, MO, P, SCA, WAG, YA); subplot 14C, tree number P3692, fr. 20 Oct. 2005, Burgt & Eyakwe 782 (K, MO, SCA, WAG, YA); subplot 10H, juvenile tree, 18 Nov. 2005, Burgt & Motoh 800 (BR, G, K, MO, P, SCA, WAG, YA); subplot 14C, tree numbers P3692 and P3694, fl., 30 Sept. 2006, Burgt & Motoh 901 (K, YA); Korup National Park, fl. 5 – 15 Dec. 1984, D. W. Thomas 4140 (K, MO); Korup National Park, between Ikenge and Bajo villages, sterile, 7 April 1988, D. W. Thomas 7673 (MO).

habitat. Gilbertiodendron newberyi occurs in evergreen rain forest, at 0 – 800 m asl.

conservation status. Gilbertiodendron newberyi was assessed according to IUCN criteria as Endangered D (Burgt et al. 2012). At the recently discovered site of Burgt 1661 in the Ebo proposed National Park, two mature trees were seen, standing close to each other at the edge of old farmland. A search of two weeks around the site of Burgt 1661 did not result in the discovery of additional trees. The total number of trees known is therefore still between 50 and 250, resulting in Endangered under criterion D (Table 1).

etymology. Gilbertiodendron newberyi is named after Professor David M. Newbery of the Institute of Plant Sciences, University of Bern.

notes. The flower bracts and bracteoles on the newly made collection Burgt 1661 are somewhat larger than those on the type; therefore the new description was adapted from Burgt et al. (2012). Gilbertiodendron newberyi resembles G. quinquejugum from Gabon, Congo (Brazzaville) and Angola (Cabinda). The main differences between the two species are found in the size of the leaves and leaflets, the size of the bracteoles, and the hairs on the bracteoles. The results of a phylogenetic study of Estrella et al. (2014) confirm the existence of two separate species. Gossweiler 7592 and 8172, named to G. quinquejugum, resemble G. newberyi in the size of the bracteoles, but the leaves and leaflets of these two collections are much smaller (see notes at G. quinquejugum).

8. Gilbertiodendron quinquejugum Burgt, sp. nov. Type: Gabon, Moyen-Ogooué, Missanga, 5 – 15 km NNW of Ndjolé, 14 Nov. 1991, F. J. Breteler & C. C. H. Jongkind 10482 (holotype WAG! [WAG0164246 – 248], isotypes G!, IEC, LBV!, W).

http://www.ipni.org/urn:lsid:ipni.org:names:77146138-1

Macrolobium mayombense Pellegr. var. parvifolium Baker f. (Baker 1928: 140); Syntypes: Gossweiler 7592, 8172; Baker (1930: 676); Léonard (1954: 61); Léonard (1957: 238); Aubréville (1968: 220); Aubréville (1970: 204).

[Macrolobium ogoouense auct. (Pellegrin 1941: 506); in part, for the syntype Le Testu 5071 only; not for its type.]

Tree, 12 to 40 m tall. Trunk straight, cylindrical, to 60 cm diam. Twigs sparsely puberulent to glabrescent, hairs to 0.2 mm long. Stipules in pairs, free, reniform part persistent, flat, 7 – 15 × 5 – 13 mm, glabrescent to glabrous; lanceolate part of stipule early caducous, 10 – 12 × 1 mm. Leaves paripinnate, to 22 × 13 cm; petiole 4 – 7 mm long, 1.5 – 3 mm diam., puberulent to glabrescent, hairs to 0.1 mm long; leaf rachis 3 – 16 cm long, puberulent to glabrescent, hairs to 0.1 mm long, stipels absent; petiolules 1 – 3 mm long, puberulent to glabrescent, hairs to 0.1 mm long. Leaflets papery, opposite, 3 – 5 (– 6) pairs, elliptic, 4 – 12 × 1.5 – 4 cm; smooth and somewhat glossy both sides, upper surface glabrous, lower surface glabrescent to glabrous, same colour or slightly lighter; midrib glabrous above, prominent and sparsely puberulent to glabrescent below, hairs to 0.1 mm long; 6 – 9 pairs of secondary veins; leaflet base cuneate to obtuse, slightly oblique; apex acuminate and mucronate, acumen 0.5 – 2 cm long. Glands 0 (– 1) per leaflet, at the proximal margin 2 – 5 mm from the apex and at the distal margin 4 – 10 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 8 cm long, densely puberulous, hairs to 0.3 mm long, internodes 4 – 7 mm long; lateral axes to 4 cm long, 8 – 10 flowers per cm. Flowers fragrant, floral bract inserted at base of pedicel, caducous, ovate, 1.5 – 3 × 1 – 2 mm, densely puberulous on both sides, hairs to 0.3 mm long, centre inside glabrous; pedicel 8 – 15 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with dense dark brown hairs to 0.4 mm long; bracteoles 2, elliptic to lanceolate, greenish to pinkish white, 8 – 11 × 5 – 6 mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.4 mm long, more dense at base and along margins; sparsely puberulous inside, centre inside glabrous; receptacle 2 mm high, 2.5 mm diam. at top, upper part glabrous, lower part with 4 patches of hairs, or a band of hairs of irregular width, hairs 0.5 mm long; sepals 5, white, narrowly triangular, 5 – 7 × 1.5 – 2 mm, apex acute, glabrous except for a few hairs on the abaxial sepal at the base outside; petals 5, alternate to sepals, white; adaxial petal white to pale pink, glabrous, claw 5 – 6 mm long, blade bilobed, 6 – 8 mm high × 12 mm wide; the other 4 petals glabrous, narrowly triangular, 5 – 6 × 1 mm, apex acute, sometimes with a few hairs on lower part outside; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 15 – 20 mm long; anthers glabrous, 2 – 3 mm long; 6 staminodes, filiform, to c. 0.5 mm long, inserted on a staminodal tube c. 0.6 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 4 × 2 × 0.5 mm, 5 – 6 ovules, margins densely hirsute, hairs to 1 mm long, sides glabrous; stipe 1 mm long; style 15 – 18 mm long, lower part hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 1 – 6-seeded, 10 – 17 × 5 – 7 cm, valve 3 mm thick, beak 1 – 3 mm long, sutures not winged; 2 – 3 longitudinal ridges running from the base to the apex, parallel to and at 0.5 – 3.5 cm distance to the upper suture. Figs 12, 13; Map 10.

Fig. 12

A pair of stipules of Gilbertiodendron quinquejugum. The reniform part of the stipule is 24 × 14 mm; the lanceolate part 12 × 1 mm. The collection was made from a juvenile tree of 4 m high. On mature trees the reniform part of the stipule is smaller; the lanceolate part has not been seen. From Nkouka 1305 (K).

Fig. 13

Gilbertiodendron quinquejugum. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel; D fruit. A – D from Breteler 10482 (WAG). drawn by margaret tebbs.

Map 10

Distribution of Gilbertiodendron quinquejugum.

recognition. Gilbertiodendron quinquejugum is related to G. ogoouense. Gilbertiodendron quinquejugum has 3 – 5 (– 6) pairs of leaflets; G. ogoouense has (2 –) 3 pairs of leaflets. The pedicel of G. quinquejugum is 8 – 15 mm long and the size of the bracteoles is 8 – 11 × 5 – 6 mm. The pedicel of G. ogoouense is 6 – 11 mm long, and the size of the bracteoles is 5 – 7 × 4 – 5 mm. The bracteoles of G. quinquejugum are densely puberulous outside, with dense light-coloured hairs to 0.1 mm long mixed with dense dark brown hairs to 0.4 mm long; in G. ogoouense the bracteoles are also puberulous outside but less dense, with light-coloured hairs to 0.2 mm long (on specimens from Cameroon mixed with sparse dark brown hairs to 0.3 mm long).

distribution. Gilbertiodendron quinquejugum occurs in Gabon, Congo (Brazzaville) and Angola (Cabinda) (Map 10).

specimens examined. gabon. Moyen-Ogooué, Missanga, 5 –15 km NNW of Ndjolé, fl. & fr., 14 Nov. 1991, Breteler 10482 (holotype WAG!, isotypes G!, IEC, LBV!, W); c. 10 km NNW of Ndolé, fr., 25 Sept. 1994, Breteler 12993 (BR, LBV, MO, WAG); Ngounié, Guidouma, fl., 18 Nov. 1924, Le Testu 5071 (syntype of Macrolobium ogoouense Pellegr.; B, BM, BR, K, LISC, P, WAG); Doudou Mts, 35 km SW of Doussala, fr., Reitsma 1435 (LBV, MO, NY, WAG); Nyanga, c. 50 km SW of Doussala, fr., 16 April 1987, Reitsma 3284 (LBV, MA, NY, WAG); Nyanga, Doudou Mts, fl. & fr., 28 Nov. 2003, Valkenburg 2635 (BR, K, P, WAG); same loc., sterile, Valkenburg 2636 (P, WAG); Nyanga, Moukalaba Doudou national park, sterile, 20 Feb. 2004, Valkenburg 2866 (LBV, MO, NY, WAG); Ogooué-Maritime, Gamba, 2 km NE of Yenzi, fr., 30 July 1992, Wieringa 1329 (LBV, WAG); Ogooué-Maritime, 35 km S of Rabi, along the Echira R., fl., 27 Nov. 1989, J. de Wilde 9800 (LBV, WAG); Ngounié, 20 km SE of Mouila, fl., 2 Nov. 1984, Wilks 1007 (LBV). congo (brazzaville). Lekoumou Préfecture, between villages Yagadobema, Lewala and Lebayi, fr., 19 May 2010, Bongou 105 (BR, G, IEC, K, MO, P, US, WAG); between Moussaou and Dziba Dziba, sterile, 25 May 2010, Kami 4991 (IEC); N of Lebayi, sterile, 1 June 2010, Kami 5345 (IEC, K); Kouilou, Mayombe hills, near Niari R., fr., 12 Oct. 2010, M'Boungou 415 (IEC, K, WAG, MO); Lekoumou Préfecture, between Inde and Lefoutou, sterile, 18 May 2010, Nkouka 973 (IEC); same loc., sterile, 24 May 2010, Nkouka 1305 (IEC, K); N of Lewala, sterile, 31 May 2010, Nkouka 1569 (IEC, K); Kouilou, Dimonika, near M'Vouti, fr., 18 June 1947, Normand DN15 (P); Kouilou, Kibayu, fr., 4 March 1920, Sargos 104 (P). angola (cabinda). Cabinda, Maiombe, Belize, fr., April 1917, Gossweiler 7139 (BM, K); same loc., fl., 18 Nov. 1918, Gossweiler 7554 (LISC); Cabinda, Maiombe, Chiluango, near Belize, banks of Luali R. above the official Residence, fl., 2 Dec. 1918, Gossweiler 7592 (BM, COI, K, LISC, MO); same loc., fl., 10 Dec. 1918, Gossweiler 7612 (BM, BR, COI, K, LISC); same loc., fr., 20 March 1919, Gossweiler 7948 (BM, COI, K, LISC); Cabinda, Maiombe, Chiluango, banks of Belize R. near confluence with Luali R., fl., 1919, Gossweiler 8172 (BM, COI, K, LISC).

habitat. Gilbertiodendron quinquejugum occurs in evergreen rain forest on well-drained soil, at 0 – 600 m asl.

conservation status. Gilbertiodendron quinquejugum is assessed here according to IUCN criteria as Least Concern (Table 1).

etymology. The species epithet of Gilbertiodendron quinquejugum refers to the leaves, which usually have a maximum of 5 pairs of leaflets. However, 6 pairs of leaflets occur occasionally (Gossweiler 7612; Normand DN15); while leaves of juvenile trees may have up to 7 pairs of leaflets (M'Boungou 415). Two collections from mature trees have a maximum of 4 pairs of leaflets (Valkenburg 2635 and J. de Wilde 9800).

notes. One of the four syntypes of Gilbertiodendron ogoouense, Le Testu 5071, is presently included in G. quinquejugum. This specimen was already noted by Pellegrin (1941: 506) to be somewhat different from the other syntypes; he remarked that the leaves have 3 – 4 pairs of leaflets and that the stamens and style are longer. Le Testu 5071 has up to 5 pairs of leaflets (BM), and also has longer, more elliptic bracteoles, densely puberulous outside, with dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.4 mm long.

A phylogenetic study by Estrella et al. (2014) places one of the flowering collections of Gilbertiodendron quinquejugum (Valkenburg 2635) in the G. ogoouense species complex, thereby confirming the results of the morphological study. This study also confirms that Bongou 105, M’Boungou 415 and Valkenburg 2636 represent G. quinquejugum.

The taxon Macrolobium mayombense Pellegr. var. parvifolium Baker f. was described by Baker (1928: 140), with syntypes Gossweiler 7592 and 8172 from Angola (Cabinda), and was made a synonym of Gilbertiodendron ogoouense by Léonard (1954: 61). M. mayombense var. parvifolium is presently made a synonym of G. quinquejugum, although there is a difference in the flowers between the two taxa: the pedicel of Gossweiler 7592 and 8172 is 4 – 9 mm long (not 8 – 15 mm) and the bracteoles are 6 – 8 mm long (not 8 – 11 mm long). This difference might justify a division into different taxa; however, the leaves of Gossweiler 7592 and 8172 are identical to those of Gossweiler 7612 and 7948, which are named to G. quinquejugum. See also the notes under G. newberyi.

Sterile material of Gilbertiodendron quinquejugum is difficult to separate from G. breteleri; see the notes under that species.

9. Gilbertiodendron breteleri Burgt, sp. nov. Type: Gabon, Ogooué-Lolo, about 30 km E of Lastoursville, near Bambidie, 7 Oct. 1997, F. J. Breteler & M. E. Leal 14250 (holotype WAG! [WAG0090697, WAG0090698], isotypes BR!, BRLU, E, K!, LBV!, M, MA, MO, NY, P, US).

http://www.ipni.org/urn:lsid:ipni.org:names:77146139-1

Tree, to c. 40 m tall. Trunk straight, to 80 cm diam. Twigs puberulent, hairs erect, to 0.3 mm long. Stipules in pairs, free; reniform part persistent, flat, 12 – 25 × 8 – 20 mm, sparsely puberulent both sides; lanceolate part of stipule early caducous, c. 11 × 1 mm. Leaves paripinnate, to 40 × 25 cm; petiole 5 – 9 mm long, 2 – 5 mm diam., puberulent, hairs 0.2 mm long; leaf rachis 5 – 18 (– 26) cm long, puberulent, stipels absent; petiolules 2 – 5 mm long, puberulent, hairs to 0.2 mm long. Leaflets somewhat coriaceous, opposite, 3 – 6 pairs, narrowly elliptic, 5 – 14 (– 18) × 2 – 4 (– 5.5) cm, above smooth and somewhat glossy with prominent venation, below dull, lighter in colour, densely papillose, with a granulate cellular structure (visible only by microscope); above glabrescent to glabrous, below sparsely persistent puberulent, hairs appressed, to 0.1 mm long; midrib sparsely puberulent both sides, below prominent; 7 – 10 pairs of secondary veins; leaflet base cuneate to obtuse, slightly oblique; apex acuminate and mucronate, acumen 0.5 – 1.5 cm long. Glands 0 – 1 (– 3) per leaflet, at the proximal margin 1 – 18 mm from the apex and at the distal margin 2 – 5 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 7 cm long, densely puberulous, hairs to 0.3 mm long, internodes 4 – 8 mm long; lateral axes to 4 cm long, with c. 10 flowers per cm. Flowers: floral bract inserted at base of pedicel, caducous, broadly ovate, 3 × 3 mm, densely puberulous outside, light-coloured hairs to 0.2 mm long mixed with a few dark brown hairs to 0.3 mm long, puberulous inside near margins, centre inside glabrous; pedicel 3 – 8 mm long, densely puberulous, dense light-coloured hairs to 0.2 mm long mixed with dense dark brown hairs to 0.4 mm long; bracteoles 2, elliptic, greyish green, 8 – 9 × 5 – 6 mm, densely puberulous outside, dense light-coloured hairs to 0.2 mm long, sparse dark brown hairs to 0.3 mm long at base and along margins; sparsely puberulous inside near apex and margins, hairs to 0.2 mm long, centre inside glabrous; receptacle 1.5 mm high, 3 mm diam. at top, a band of hairs 1 mm wide outside at base, upper part glabrous; sepals 5, white, glabrous except for a few hairs on lower margins of abaxial sepal, narrowly triangular, 5 × 2.5 – 3 mm, apex acute, margins with a few teeth; petals 5, alternate to sepals, white, glabrous, adaxial petal claw 5 – 7 mm long, blade bilobed, 6 mm high × 10 mm wide; the other 4 petals 4 – 5 × 2 mm, margins incised, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 19 – 22 mm long; anthers glabrous, 2 – 2.5 mm long; 6 staminodes, filiform, to c. 2 mm long, inserted on a staminodal tube c. 1 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 4 × 2 × 0.5 mm, 5 – 6 ovules, margins densely hirsute, hairs to 0.8 mm long, sides glabrous, stipe 1 mm long; style 13 – 17 mm long, lower part sparsely hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 1 – 3 -seeded, 10 – 21 × 5 – 7 cm, valve 3 mm thick, beak 2 – 3 mm long, sutures not winged; 2 – 2.5 longitudinal ridges running from the base to the apex, parallel to and at 0.3 – 2.8 cm distance to the upper suture. Seedlings: hypocotyl 4 – 8 cm long, epicotyl 7 – 11 cm long; first two leaves opposite, petiole and rachis 2 cm long, petiolules 1 mm long, 1 – 2 pairs of leaflets 9 – 11 × 3.5 – 4 cm (in reality 2 – 3 pairs of leaflets, lowest pair usually reduced to < 3 mm long, sometimes up to 3 × 1 cm). Fig. 14; Map 11.

Fig. 14

Gilbertiodendron breteleri. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel. A – C from Breteler 14250 (WAG). drawn by margaret tebbs.

Map 11

Distribution of Gilbertiodendron breteleri.

recognition. Gilbertiodendron breteleri is related to G. quinquejugum. The rachis is somewhat longer, 5 – 18 (– 26) cm long; not 3 – 16 cm long. The leaflets are somewhat larger, up to 14 (– 18) × 4 (– 5.5) cm; not up to 12 × 4 cm. The leaflets of G. breteleri are dull and densely papillose below, with a granulate cellular structure (visible only by microscope), not somewhat glossy and smooth as in G. quinquejugum. The leaflets of G. breteleri are also sparsely persistent puberulent below, with hairs to 0.1 mm long; not glabrescent to glabrous. The pedicel is 3 – 8 mm long; not 8 – 15 mm long as in G. quinquejugum.

distribution. Gilbertiodendron breteleri is endemic to Gabon (Map 11).

specimens examined. gabon. Ogooué-Lolo, about 30 km E of Lastoursville, fr. and seedlings, 7 May 1992, Breteler 11367 (WAG); Ogooué-Lolo, about 30 km E of Lastoursville, near Bambidie, fl., 7 Oct. 1997, Breteler 14250 (holotype WAG!, isotypes BR!, BRLU, E, K!, LBV!, M, MA, MO, NY, P, US); same loc., fl., 17 Nov. 1999, Breteler 15510 (LBV, WAG); Ogooué-Lolo, Bambidie, transect 100, fr., seedlings, 29 March 1997, Dibata 1219A (WAG); Oveng, sterile, 24 June 1985, Reitsma 1203 (LBV, NY, WAG); same loc., sterile, 5 Nov. 1986, Reitsma 2480 (LBV, MO, NY, WAG); c. 50 km SE of Makokou, near village Ekobakoba, sterile, 9 Dec. 1986, Reitsma 2724 (LBV, MO, NY, WAG); c. 35 km ENE of Lastoursville, 7 km on forestry road from Bambidie to Mbelata, sterile, 23 Jan. 2008, Wieringa 6099 (LBV, WAG); c. 30 km E of Lastoursville, 5 km on a forestry road heading S from Bambidie, fr., 26 Jan. 2008, Wieringa 6190 (LBV, WAG); same loc., sterile, 26 Jan. 2008, Wieringa 6191 (WAG); same loc., sterile, 20 March 2013, Wieringa 7559 (WAG); Woleu-Ntem, Minkébé region, sterile, 10 Feb. 1990, Wilks C 118 (WAG).

habitat. Gilbertiodendron breteleri occurs in evergreen rain forest; at 300 – 600 m asl.

conservation status. Gilbertiodendron breteleri is assessed here according to IUCN criteria as Vulnerable B1ab(i,iii,v) (Table 1). Although the Extent of occurrence is 24.100 km², which is larger than the threshold of 20.000 km², Vulnerable is chosen because G. breteleri is a possible timber species and 9 of the 10 sites are located outside protected areas.

etymology. The species epithet of Gilbertiodendron breteleri refers to Frans J. Breteler, who collected the type specimen together with Miguel Leal. From his base at the WAG Herbarium in Wageningen, The Netherlands, Frans Breteler has been studying the flora of Gabon for many years. The new species was discovered thanks to the two excellent flowering collections which he made.

notes. A phylogenetic study by Estrella et al. (2014) places the type of Gilbertiodendron breteleri (Breteler 14250) in the G. ogoouense species complex, thereby confirming the results of the morphological study. This study also confirms that Wieringa 6099, 6190 and 6191 are conspecific with the type of G. breteleri.

The leaflets of Gilbertiodendron breteleri are papillose beneath, with a granulate cellular structure, best visible by microscope with light coming sideways. This is an important difference with G. quinquejugum, of which the leaflets beneath are smooth and somewhat glossy. The lower surface of the leaflets of G. breteleri appears dull and lighter in colour than the upper surface; while the lower surface of the leaflets of G. quinquejugum appears identical or slightly lighter in colour than the upper surface. This difference is obvious on the leaflets of the flowering collections Breteler 14250 and 15510, but less well visible on the leaflets of the juvenile trees of Wieringa 6099, 6190 and 6191. Presumably the papillose character of the leaflets only develops well in leaflets exposed to full sunlight at the outer canopy. Four sterile collections, Reitsma 1203, 2480, 2724 and Wilks C 118, show the papillose lower leaflet surface and are therefore identified to G. breteleri. Two sterile collections, Breteler 11367 and Wieringa 7559, are placed in G. breteleri because they have been collected near the type locality; they might also be G. quinquejugum, although this species is not known from the Ogooué-Lolo province.

The collection Dibata 1219 at WAG is likely a mixture of Gilbertiodendron breteleri (2 sheets) and G. klainei or G. scutatum (1 sheet; barcoded with a number out of sequence). Presumably this is a curation error.

Most collections of Gilbertiodendron breteleri, including the type, were collected in the Lastoursville area. There are currently 25 plant species known to be endemic to this area (Wieringa & Mackinder 2012; Velzen & Wieringa 2014), which is a considerable number. This adds support for the creation of a protected area in this part of Gabon.

10. Gilbertiodendron bambolense Burgt, sp. nov. Type: Zaire [Congo (Kinshasa)], Yahila (Bambole), rive gauche en face de Yangambi, le long de la rivière Loowe, 11 Sept. 1938, J. Louis 11234 (holotype K! [K000745742], isotypes BR!, WAG!).

http://www.ipni.org/urn:lsid:ipni.org:names:77146140-1

Macrolobium bambolense Louis (Louis & Fouarge 1949: 9 – 11, 14, 16), nom. nud.; Léonard (1954: 61); Léonard (1957: 238); Aubréville (1968: 221); Aubréville (1970: 204).

Tree, to c. 40 m tall. Trunk straight, cylindrical, to 120 cm diam. Twigs glabrescent or glabrous. Stipules in pairs, free; reniform part persistent, flat, 10 – 22 × 6 – 15 mm, glabrescent or glabrous; lanceolate part of stipule not seen. Leaves paripinnate, to 32 × 20 cm; petiole 3 – 8 mm long, 1.5 – 4 mm diam., sparsely puberulent with hairs to 0.4 mm long, or glabrous; leaf rachis 7 – 27 cm long, glabrous, rachis of juvenile leaves sparsely puberulent, hairs to 0.3 mm long, stipels absent; petiolules 2 – 4 mm long, sparsely puberulent to glabrous, with hairs to 0.3 mm long. Leaflets papery, opposite, 4 – 7 pairs, narrowly elliptic to elliptic, 5 – 13 (– 20) × 1.5 – 5 (– 6) cm; smooth, somewhat glossy and glabrous both sides, lower surface same colour or somewhat lighter, midrib glabrous above, glabrescent to glabrous and prominent below; 7 – 10 pairs of secondary veins; leaflet base cuneate to obtuse, slightly oblique; apex acuminate and mucronate, acumen 0.3 – 1.5 cm long. Glands 0 – 1 (– 2) per leaflet, at the proximal margin 10 – 25 mm from the apex and at the distal margin 3 – 10 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 16 cm long, puberulous, hairs to 0.4 mm long, internodes 3 – 20 mm long; lateral axes to 5 cm long, 10 – 12 flowers per cm. Flowers: floral bract inserted at base of pedicel, caducous, ovate, 5 × 3.5 mm, densely puberulous outside, sparsely puberulous inside, hairs to 0.2 mm long; pedicel 5 – 10 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with dark brown hairs to 0.4 mm long; bracteoles 2, elliptic, 6 – 7 × 5 – 6 mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed with sparse dark brown hairs to 0.3 mm long, sparsely puberulous inside, centre inside glabrous; receptacle 1 mm high, 2 mm diam. at top, glabrous; sepals 5, glabrous, narrowly triangular, 4 × 1 mm, apex acute; petals 5, alternate to sepals, glabrous; adaxial petal white, claw 5 – 6 mm long, blade bilobed, 6 – 7 mm high × 10 – 12 mm wide; the other 4 petals 3.5 × 0.8 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments glabrous, 10 – 12 mm long; anthers glabrous, 2.5 mm long; 6 staminodes, filiform, to c. 1 mm long, inserted on a staminodal tube c. 0.8 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary 3 × 1.5 × 0.5 mm, 4 – 5 ovules, margins densely hirsute, hairs to 0.8 mm long, sides glabrous; stipe 1 mm long; style 11 – 13 mm long, lower part hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 13 – 16 × 5 – 6 cm, valve 3 mm thick, beak 2 – 3 mm long, sutures not winged; 2.5 – 3 longitudinal ridges running from the base to the apex, parallel to and at 0.3 – 3 cm distance to the upper suture. Seedlings: hypocotyl 3 – 6 cm long, epicotyl 8 – 11 cm long; first two leaves opposite, petiole and rachis 12 – 18 mm long, petiolules 1 mm, 1 pair of leaflets 10 – 12 × 3 – 4 cm (in reality 2 pairs of leaflets, lowest pair reduced to < 3 mm long). Fig. 15; Map 12.

Fig. 15

Gilbertiodendron bambolense. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel; D branch with fruits. A from Michelson 873 (K); B, C from Louis 11234 (K); D from A. Léonard 5149 (K). drawn by margaret tebbs.

Map 12

Distribution of Gilbertiodendron bambolense.

recognition. Gilbertiodendron bambolense is related to G. sulfureum. G. bambolense is a large tree from forest on well-drained soil, while G. sulfureum is a small to medium-sized tree from swamp forest. The twigs and rachis of G. bambolense are glabrescent to glabrous, if hairs are present they are sparse and to 0.3 mm long. The twigs and rachis of G. sulfureum are puberulent with hairs to 0.2 mm long. The leaves of G. bambolense have 4 – 7 pairs of leaflets. The leaves of G. sulfureum have more pairs of leaflets, 4 – 9 (– 10) pairs. The leaflets of G. bambolense are glabrous beneath; the midrib beneath is glabrescent to glabrous. The leaflets of G. sulfureum are sparsely puberulent to glabrescent beneath. The bracteoles of G. bambolense are dark brown in colour when dried; the bracteoles of G. sulfureum are yellowish light brown when dried.

distribution. Gilbertiodendron bambolense is endemic to Congo (Kinshasa) (Map 12).

specimens examined. congo (kinshasa). Ngoli, sterile, 11 Feb. 1980, Ankei 79/1102 (BR); Région de l'Equateur, zone d'Ikela village Balanga, route de Lokofe-Ikumaloki au Nord de la Tshuapa, fr., Bermejo 32A (BR); Tshiole, territoire de Dimbelenge, bassin de la rivière Kunduie, fr., 1 June 1954, Collin 12 (BR); Equateur, Bokungu, route Bokota-Yalifafu, fr., 13 Feb. 1959, Evrard 5708 (BM, BR, K); River Ndiba, route Isangi-Yabahondo, fr., March 1956, Germain 8694 (BR, WAG); Kasai, Territoire de Demba, fr., 6 July 1951, Jacques 36 (BR, K); Bulumbu, Shabunda, fl., 9 April 1959, A. Léonard 3751 (BR, C, K, MO, WAG); Kivu, Shabunda, Kingulube, fr., July 1959, A. Léonard 5149 (K, P, WAG); Masanga, Shabunda, 700 m, fr., 17 August 1959, A. Léonard 5825 (BR, MO, WAG); Japeke, Bamboli culture, sterile, Dec. 1943, Liegeois 108 (BR); Yahila (Bamboli), rive gauche en face de Yangambi, 470 m, fl., 10 Sept. 1938, J. Louis 11208 (BR, K); Yahila (Bambole), rive gauche en face de Yangambi, le long de la rivière Loowe, 470 m, fl., 11 Sept. 1938, J. Louis 11234 (holotype K!, isotypes BR!, WAG!); km 25 C.F.L. first troncon Stanleyville, 470 m, fl. & fr., 3 Jan., 23 & 26 Feb. 1939, van der Meiren 52 (BM, BR, C, K, NY); Forestier Central, Pangi, route de Kailo, sterile, 24 June 1942, Michelson 160 (BR); Forestier Central, Shabunda, Cobelmin, fr., Oct. 1943 – Jan. 1944, Michelson 537 (BR); sin. loc., sterile, Oct. 1943, Michelson 549 (BR); R. Lonioma, near confluence with Lualaba R., fl., Oct. – Nov. 1945, Michelson 661 (BR, K); Province Kivu. Territoire Shabunda, abords du poste Niangoma, fl., 22 Jan. 1949, Michelson 873 (BR, K); sin. loc., fl. & fr., 1941, Tondeur 92 (BR).

habitat. Gilbertiodendron bambolense occurs in evergreen rain forest on well-drained soil, at 400 – 800 m asl.

conservation status. Gilbertiodendron bambolense is assessed here according to IUCN criteria as Least Concern (Table 1).

etymology. The species epithet of Gilbertiodendron bambolense refers to the Bambole (BaMbole, Mbole) ethnic group from the centre of Congo (Kinshasa).

notes. The name Macrolobium bambolense Louis appears in Louis & Fouarge (1949: 9 – 11, 14, 16) and on some of the specimens, e.g. Louis 11208 (BR, K) and Louis 11234 (BR, K): Macrolobium bambolense Louis sp. nov.; det.: 9 Aug. 1949. However, J. Louis never published this name according to the Code; no Latin description was published.

The only clear difference between Gilbertiodendron bambolense and G. ogoouense is in the number of pairs of leaflets: 4 – 7 pairs of leaflets versus (2 –) 3 pairs; and consequently in the length of the rachis. The inflorescences and flowers of both species are more or less identical. However, the flower bract of G. bambolense is 5 mm long; while that of G. ogoouense is 3 mm long. G. bambolense has denser, longer and darker hairs on the pedicel and bracteoles, compared to G. ogoouense.

All specimens cited in the Flore du Congo Belge et du Rwanda-Urundi under Gilbertiodendron ogoouense (Léonard 1952b: 433) are G. bambolense. However, the description in this flora applies to G. ogoouense s.l.

11. Gilbertiodendron sulfureum Burgt, sp. nov. Type: Gabon, Haute Ngounyé, entre Ndamba et Mimongo, 4 April 1926, G. M. P. C. Le Testu 5891 (holotype P! [P00754999], isotypes BM!, BR!, HBG!, NY!, WAG!).

http://www.ipni.org/urn:lsid:ipni.org:names:77146141-1

Macrolobium brachystegioides Harms var. sulfureum Pellegr. (Pellegrin 1941: 506), nom. nud.; Pellegrin (1949: 52); Léonard (1954: 61); Léonard (1957: 238); Aubréville (1968: 221; 1970: 204).

Tree, 5 – 23 m tall. Trunk to 35 cm diam. Twigs puberulent, hairs to 0.2 mm long. Stipules in pairs, free, reniform part persistent, flat, 10 – 22 × 7 – 18 mm, sparsely puberulent to glabrescent both sides; lanceolate part of stipule not seen. Leaves paripinnate, to 26 × 16 cm; petiole 4 – 7 mm long, 2 – 3 mm diam., sparsely puberulent, hairs to 0.1 mm long; leaf rachis (3 –) 6 – 21 (– 24) cm long, puberulent, hairs to 0.1 mm long, stipels absent; petiolules 1 – 3 mm long, sparsely puberulent, hairs to 0.1 mm long. Leaflets papery, opposite, 4 – 9 (– 10) pairs, narrowly elliptic, 4 – 11 × 1.3 – 3.5 cm; smooth and somewhat glossy both sides, upper surface glabrous, lower surface same colour, sparsely puberulent to glabrescent, hairs appressed, to 0.1 mm long; midrib prominent both sides, glabrescent to glabrous above, sparsely puberulent below, hairs to 0.1 mm long; 10 – 12 pairs of secondary veins; leaflet base cuneate to obtuse, slightly oblique, apex acuminate and mucronate, acumen 0.5 – 2 cm long. Glands 0 – 1 (– 2) per leaflet, at the distal margin 2 – 5 mm from the petiolule and occasionally at the proximal margin 10 mm from the apex. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, densely puberulous, hairs to 0.4 mm long, internodes between fertile twig nodes becoming as short as 5 mm towards the apex of the twig, creating a dense cluster of panicles each 3 – 12 (– 19) cm long, panicle internodes 4 – 12 (– 20) mm long; lateral axes to 4 cm long, 10 – 12 flowers per cm. Flowers slightly fragrant, floral bract inserted at base of pedicel, caducous, ovate, 2 × 1.5 mm, densely puberulous on both sides, hairs to 0.2 mm long, centre inside glabrous; pedicel 6 – 13 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with dense dark brown hairs to 0.4 mm long; bracteoles 2, elliptic, yellowish white, 5 – 6 (– 7) × 4 (– 5) mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed at base with sparse dark brown hairs to 0.2 mm long, sparsely puberulous inside, centre inside glabrous; receptacle 1.5 mm high, 2 mm diam. at top, glabrous or with patches of hairs on adaxial and/or abaxial sides, hairs 0.3 mm long; sepals 5, narrowly triangular, 4 × 1 mm, apex acute, glabrous, sometimes a few hairs at the base outside; petals 5, alternate to sepals; adaxial petal white, glabrous, claw 3 mm long, blade bilobed, 4 – 5 mm high × 8 – 10 mm wide; the other 4 petals glabrous, narrowly triangular, 3 – 4 × 0.8 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 10 – 11 mm long; anthers glabrous, 2 mm long; 6 staminodes, filiform, to c. 0.5 mm long, inserted on a staminodal tube c. 0.5 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 2.5 × 1.5 × 0.5 mm, 4 – 5 ovules, margins densely hirsute, hairs to 0.8 mm long, sides glabrous; stipe 0.5 mm long; style white, 8 – 10 mm long, lower part hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 11 – 13 × 4 – 5 cm, valve 3 mm thick, beak 1 – 3 mm long, sutures not winged; 2 – 2.5 longitudinal ridges running from the base to the apex, parallel to and at 0.3 – 2 cm distance to the upper suture. Fig. 16; Map 13.

Fig. 16

Gilbertiodendron sulfureum. A branch with inflorescences; B leaf with pair of stipules; C leaflet lower surface; D floral bract; flower buds with short and long pedicel; E branch with fruit. A, C, D from J. de Wilde 8431 (WAG); B from Le Testu 5891 (P); E from Breteler 12862 (WAG). drawn by margaret tebbs.

Map 13

Distribution of Gilbertiodendron sulfureum.

recognition. Gilbertiodendron sulfureum is related to G. brachystegioides. It is a small to medium-sized tree from swamp forest, while G. brachystegioides is a large tree from forest on well-drained soil. The stipules are reniform, but flat; a pair of stipules is not strongly inrolled towards each other. The leaflets have an acumen of 0.5 – 2 cm long; not 0 – 1 cm long as in G. brachystegioides. The pedicel is 6 – 13 mm long; not 10 – 25 mm long. The dried bracteoles are light yellowish brown in colour, not dark brown in colour. The pods are 11 – 13 × 4 – 5 cm, not 12 – 19 × 5 – 7 cm as in G. brachystegioides.

distribution. Gilbertiodendron sulfureum is known from Gabon and southern Cameroon (Map 13).

specimens examined. cameroon. Between Sangmelima and Ebolowa, fl., 1910 – 1911, Mildbraed 5569 (HBG); N'Koemvone, 14 km on road Ebolowa to Ambam, fl., 18 Aug. 1975, J. de Wilde 8431 (AAU, B, BR, C, HBG, K, M, MA, NY, P, PRE, WAG, YA). gabon. Ivindo-Méko National Park, fl., 11 Sept. 2006, Boupoya 365 (BRLU, K, WAG); Woleu-Ntem, Cristal Mts, Assok, fr., 14 Sept. 1994, Breteler 12862 (BR, K, LBV, WAG); Ogooué-Lolo, Makande surroundings, about 65 km SSW of Booué, km 30 Makande – La Lopé, fr., 30 Jan. 1999, Breteler 14862 (WAG); Camp Waka, Ogoubi River, fl., 25 Feb. 2008, Dauby GD 859 (BRLU, MO); Woleu-Ntem, Minkébé region, 2200 m on transect A, sterile, 9 March 1990, Dibata in Minkébé series C 387 (WAG); Forêt des Abeilles, sterile, 10 Dec. 1993, Gesnot 251 (BRLU); Haute Ngounyé, entre Ndamba et Mimongo, fl., 4 April 1926, Le Testu 5891 (holotype P!, isotypes BM!, BR!, HBG!, NY!, WAG!); Haute Ngounyé, Lidyembo, fl., 20 June 1926, Le Testu 5963 (BM, BR, MO, P); Région de Lastoursville, Ndanda, fl., 3 June 1931, Le Testu 8844 (AAH, BM, BR, K, LISC, P); Région entre Ogooué et Cameroun, Bitam, fl., 9 March 1933, Le Testu 9017 (B, BM, BR, HBG, LISC, MO, P, S, WAG); Obour, fl., 1 May 1933, Le Testu 9094 (BM, BR, K, LISC, P); Mbolénzore, fl., 10 May 1934, Le Testu 9574 (BM, BR, IFAN, K, LISC, P); Mvomayo, fl., 23 June 1934, Le Testu 9612 (BM, BR, LISC, P, WAG); Ogooué-Ivindo, Mitendi, sterile, 20 Nov. 2000, Leal 210 (WAG); Ogooué-Ivindo, Ivindo National Park, Massouma 2000, rivière Djidji, fl., 1 May 2004, Moungazi 1604 (WAG).

habitat. Gilbertiodendron sulfureum occurs in periodically inundated evergreen rain forest and swamp forest, at 200 – 700 m asl.

conservation status. Gilbertiodendron sulfureum is assessed here according to IUCN criteria as Least Concern (Table 1). Being a small to medium-sized tree, the species is presumably only indirectly threatened by logging.

etymology. The species epithet of Gilbertiodendron sulfureum refers to the yellowish brown colour of the dried bracteoles.

notes. Macrolobium brachystegioides var. sulfureum was published invalidly by Pellegrin (1941: 506). Specimens cited: Le Testu 5891, 5963, 8844, 9017, 9094, 9574, 9612. This taxon was not published in accordance with the Code: there is no Latin description. Although Pellegrin published the new taxon as a variety, he suspected the taxon to be a new species (Pellegrin 1941: 506, 1949: 52). Léonard (1954: 61) made the invalidly published taxon a synonym of Gilbertiodendron ogoouense, possibly because the stipules and flower buds resemble those of G. ogoouense rather than those of G. brachystegioides.

12. Gilbertiodendron brachystegioides (Harms) J. Léonard (1954: 58); Hutchinson & Dalziel (1958: 475, 477); Saint Aubin (1963: 78); Aubréville (1968: 222); Aubréville (1970: 206).

Macrolobium brachystegioides Harms (1907: 24 – 25). Type: Cameroon, Bipinde, 1 June 1905, G. Zenker 3315 (holotype B! [B100159040], isotypes BM!, BR!, E!, G!, GOET!, H!, HBG!, K!, L!, M!, MO!, P!, PR!, PRE!, S!, US!, WU!, Z!); Baker (1930: 674); Letouzey & Mouranche (1952: 65); Léonard (1954: 58); Léonard (1957: 236); Aubréville (1968: 222); Aubréville (1970: 206).

Tree, to c. 45 m tall. Trunk straight, cylindrical, to 93 cm diam. Bark light yellowish brown, exfoliating in small and thin papery flakes. Twigs sparsely puberulent, hairs to 0.3 mm long. Stipules in pairs, free; reniform part persistent, a pair of stipules strongly inrolled towards each other, 10 – 30 × 7 – 20 × 3 – 10 mm, sparsely puberulent both sides, hairs to 0.1 mm long; lanceolate part of stipule early caducous, 5 – 12 × 1 – 2 mm. Leaves paripinnate, to 35 × 15 cm; petiole 4 – 10 mm long, 2 – 4 mm diam., puberulent, hairs to 0.2 mm long; leaf rachis 6 – 22 (– 28) cm long, puberulent, hairs to 0.2 mm long, stipels absent; petiolules 1 – 2 mm long, puberulent, hairs to 0.2 mm long. Leaflets papery, opposite, 5 – 10 (– 11) pairs, upper pair oblanceolate, other pairs narrowly elliptic to elliptic, 3 – 9 (– 11) × 1 – 3 (– 5) cm (to 23 × 7 cm on juvenile trees), glabrous above, glabrescent or glabrous below, smooth and dull to somewhat glossy both sides, lower surface same colour or slightly lighter, midrib prominent below, midrib sparsely puberulent to glabrescent both sides, hairs to 0.2 mm long; 7 – 10 pairs of secondary veins; leaflet base cuneate to obtuse, oblique; apex acuminate and mucronate, acumen 0 – 1 cm long. Glands 0 – 1 per leaflet, at the proximal margin 5 – 16 mm from the apex and at the distal margin 2 – 10 mm from the petiolule. Inflorescence a congested, axillary or terminal cluster of 1 to several panicles, to 9 cm long, densely puberulous, hairs to 0.5 mm long, internodes 4 – 10 mm long; lateral axes to 7 cm long, with 10 – 12 flowers per cm. Flowers fragrant, floral bract inserted at base of pedicel, caducous, ovate, 3 – 4 × 2 mm, densely puberulous on both sides, centre inside glabrous, hairs to 0.3 mm long; pedicel 10 – 25 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with dense dark brown hairs to 0.4 mm long; bracteoles 2, elliptic, light reddish brown outside, whitish inside, 5 – 6 × 4 – 5 mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed with dense dark brown hairs to 0.4 mm long; sparsely puberulous inside, centre inside glabrous; receptacle 1 mm high, 2 mm diam. at top, outside glabrous apart from two patches of hairs at adaxial and abaxial side; sepals 5, white, glabrous, narrowly triangular, 2 – 3 × 1 mm, apex acute; petals 5, alternate to sepals, white, glabrous; adaxial petal claw 4 – 5 mm long, blade bilobed, 5 – 6 mm high × 10 – 15 mm wide; the other 4 petals 2 × 0.7 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, 10 – 12 mm long; anthers glabrous, 2 mm long; 6 staminodes, filiform, to c. 1 mm long, inserted on a staminodal tube c. 0.8 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 2.5 × 1 × 0.5 mm, 4 – 5 ovules, margins densely hirsute, hairs to 0.8 mm long, sides glabrous; stipe 1 mm long; style 10 – 14 mm long, lower part sparsely hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 0 – 5-seeded, 12 – 19 × 5 – 7 cm, valve 3 mm thick, beak 3 – 5 mm long, sutures not winged; 1.5 – 2 longitudinal ridges running from the base to the apex, parallel to and at 0.5 – 2.5 cm distance to the upper suture. Seedlings: hypocotyl 3 – 7 cm long, epicotyl 11 – 13 cm long; first two leaves opposite, petiole and rachis 4 – 6 cm long, petiolules 1 mm, 2 – 3 pairs of leaflets 7 – 10 × 2 – 3 cm (in reality 3 – 4 pairs of leaflets, lowest pair reduced to < 3 mm long). Figs 17, 18, 19; Map 14.

Fig. 17

A pair of stipules from a juvenile tree of Gilbertiodendron brachystegioides (Burgt 1711). Each of the two stipules is c. 38 × 16 × 8 mm. photo: xander van der burgt.

Fig. 18

Gilbertiodendron brachystegioides, drawn with collections from Cameroon. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel; D fruit. A, B from Foury 2 (P); C from Zenker 3315 (K); D from Burgt 697 (K). drawn by margaret tebbs.

Fig. 19

Gilbertiodendron brachystegioides, drawn with collections from Gabon. A branch with inflorescences; B leaflet lower surface; C floral bract; flower buds with short and long pedicel; D fruit; E pair of stipules. A from Wilks 1600 (WAG) and Leeuwenberg 13559 (WAG); B – D from Wilks 1600 (WAG); E from Bernard 868 (P). drawn by margaret tebbs.

Map 14

Distribution of Gilbertiodendron brachystegioides.

distribution. Gilbertiodendron brachystegioides occurs in Cameroon, Equatorial Guinea and Gabon (Map 14). The species occurs close to the Nigerian border, but is not mentioned in the book Trees of Nigeria by Keay (1989).

specimens examined. cameroon. Southwest Region, Korup National Park, Science Camp near P transect, fl., 8 Jan. 2000, Burgt 571 (BR, C, G, K, MA, MO, NY, P, PRE, S, SCA, US, WAG, YA); same loc., fr., 6 June 2000, Burgt 607 (G, SCA, WAG); same loc., fr., 27 Aug. 2004, Burgt 697 (BR, G, K, MO, P, SCA, WAG, YA); same loc., seedlings, 18 Nov. 2005, Burgt 801 (BR, G, K, MO, P, SCA, WAG, YA); Littoral Region, Ebo R., sterile, 6 Dec. 2013, Burgt 1711 (BR, K, MO, P, WAG, YA); Mt Cameroon, 3 – 5 km E of Limbe, sterile, 7 July 1992, Cheek 3495 (K); South Region, Campo, sterile, 1917, Fleury 402 (in Chevalier 33491) (P); Central Region, Yaoundé, fl.,1935, Foury 2 (P); Reserve d'Ototomo près Yaoundé, sterile, 8 June 1933, Foury 38 (P); Yaoundé, sterile, 1935, Foury 155 (P); South Region, Mvila, Ebom, Mimwo catchment, sterile, 22 Sept. 1998, Gemerden 352A (WAG); Mamfe distr., Kembong Forest Reserve, fr., 7 June 1957, Iwunze FHI 29401 (BR); Central Region, Ebonkop, near Nyong R., E of Mbalmayo, fr., 7 April 1949, Letouzey SRFK 1271 (YA); same loc., sterile, 7 April 1949, Letouzey SRFK 1272 (P, YA); South Region, km 48 route Kribi – Zingui, fl., 17 July 1950, Letouzey SRFK 1462 (LISC, P, YA); Kribi, fl., Letouzey SRFK 2646 (P, YA); South Province, 20 km ENE of Ebodie, Campo forest reserve, sterile, Oct. – Nov. 1991, McKey C91- 7 (29) (K); 25 km E of Grand Batanga, sterile, 25 July 1911, Mildbraed 6107 (HBG); Ebolowa – Yaoundé, fl., Jan. 1914, Mildbraed 7777 (K); Central Region, Mefou, sterile, 30 March 2004, Onana 2899 (K, WAG); Southwest Region, Mamfe, Cross R., fl., 17 March 1955, Onochie FHI 34837 (K); Mt Cameroon, Mabeta peninsula, sterile, 19 Oct. 1997, Tchouto (Mbatchou) 1754 (SCA); Korup National Park, sterile, March 1979, D. W. Thomas 442 (K, WAG); Korup National Park, between Baro and Ikenge villages, sterile, 1 April 1988, D. W. Thomas 7510 (MO); Korup National Park, near northern edge, Ajaman, sterile, 22 May 1988, D. W. Thomas 7832 (MO, YA); Korup National Park, S of Esukutang village, sterile, 25 May 1988, D. W. Thomas 7953 (MO); Korup National Park, between Sekim and Banyu, sterile, 25 April 1988, D. W. Thomas 8243 (MO); Southwest Region, Idenao, Onge R., sterile, 7 Nov. 1993, D. W. Thomas 9773 (K, SCA); Mt Cameroon, sterile, 9 Nov. 1993, D. W. Thomas 9842 (K, SCA); Mt Cameroon, Mokoko, sterile, 22 May 1994, D. W. Thomas 10046 (SCA); same loc., sterile, 26 May 1994, D. W. Thomas 10154 (MO, SCA); near Yaoundé, fl., 1946, Tsoungui SRFK 1085 (P, YA); South Region, Campo, on road to Mabiogo, sterile, 16 Feb. 1994, Wieringa 2242 (WAG); Bipinde, fl., 1 June 1905, Zenker 3315 (holotype B!, isotypes BM!, BR!, E!, G!, GOET!, H!, HBG!, K!, L!, M!, MO!, P!, PR!, PRE!, S!, US!, WU!, Z!). equatorial guinea. In the SE of Monte Alen National Park, N of Lana R., near the Cabaña Ecofac de Misergue, fr., 6 July 2002, Senterre 3171 (BRLU); Sofoge (Ndote), fl., 14 Aug. 1998, Wilks 3582 (BRLU). gabon. Estuaire, Bokoué, sterile, 28 Aug. 1952, Bernard SRF 868 (LBV, P); Ogooué-Lolo, about 30 km E of Lastoursville, sterile, 28 Nov. 1991, Breteler 10810 (LBV, WAG); about 55 km E of Lastoursville, sterile, 23 Nov. 1993, Breteler 12283 (WAG); Moyen-Ogooué, M'Boumi, about 30 km S of Ndjolé, on border of Ogooué R., sterile, 17 Nov. 1998, Breteler 14652 (LBV, WAG); Ogooué-Lolo, Makande surroundings, about 65 km SSW of Booué, fr., 27 Jan. 1999, Breteler 14805 (LBV, WAG); same loc., fr., 9 Feb. 1999, Breteler 14983 (WAG); Estuaire, SBM-Kougouleu, sterile, 20 Dec. 1952, Corbet 1018 (LBV); In the SW of Lopé National Park, sterile, 31 Jan. 2009, Dauby GD 1516 (BRLU); E of Ivindo National Park, sterile, 18 March 2009, Dauby GD 1782 (BRLU); S of Ivindo National Park, sterile, 13 Feb. 2010, Dauby GD 2297 (BRLU); Estuaire, N'koulounga, fl. & fr., 1 Oct. 1953, Groulez 1109 (LBV, P); same loc., sterile, 1 Oct. 1953, Groulez 1110 (LBV); Ogooué-Ivindo. Mitendi Hill, sterile, 23 Oct. 2000, Leal 187 (WAG); Woleu-Ntem, S of Medouneu, 33 km E of camp Abanga, fr., 16 Sept. 1985, Leeuwenberg 13559 (AAU, B, BR, C, LBV, K, MA, MO, P, PRE, WAG); Estuaire, Crystal Mts, 17950 m on transect F, fr., 27 Jan. 2001, Nguema Miyono 1663 (LBV, WAG); Bokoué, sterile, 1 Sept. 1958, Saint Aubin 1974 (LBV); Ogooué-Ivindo, 32 km on road Koumameyong to Lalara, sterile, 3 Oct. 1992, Wieringa 1693 (LBV, WAG); Moyen-Ogooué, 30 km ENE of Lambaréné, 10 km ENE of Bellevue, sterile, 6 April 1994, Wieringa 2661 (BR, LBV, WAG); Ogooué-Lolo, c. 55 km N of Lastoursville, foothills of Ngota Mt, sterile, 28 Jan. 2008, Wieringa 6226 (WAG); Ogooué-Lolo, 52 km WSW of Okondja, road to Bambidie, sterile, 7 Feb. 2008, Wieringa 6526 (LBV, WAG); Ngounié, 17 km ESE du confluent Ngounié × Migabi, fl., 8 June 1985, Wilks 1086 (LBV); Ogooué-Ivindo. 18 km SSW de Koumameyong, fl. & fr., 4 Aug. 1987, Wilks 1600 (WAG, MO).

habitat. Gilbertiodendron brachystegioides occurs in evergreen rain forest on well-drained soil, at 0 – 700 m asl.

conservation status. Gilbertiodendron brachystegioides is assessed here according to IUCN criteria as Least Concern (Table 1).

notes. Gilbertiodendron brachystegioides is characterised by its stipules: a pair of stipules is strongly inrolled towards each other (Fig. 17). Within the G. ogoouense species complex, this type of stipules is otherwise only seen in G. ebo and sometimes in G. minkebense and G. ngouniense, but in these species the leaflets occur in fewer pairs. Saplings of G. brachystegioides have been collected many times, presumably because the stipules and young leaves are conspicuous.

There is a remarkable difference in the number of pairs of leaflets of Gilbertiodendron brachystegioides specimens from Cameroon and those from Gabon. The most common number of pairs of leaflets on fertile specimens from Cameroon is 7, with an average of 6.9. In fertile specimens from Gabon the most common number of pairs of leaflets is 10, with an average of 8.8 (Table 4). The two known specimens from Equatorial Guinea have only one leaf each, which is too few to include in the analysis. This is the only obvious difference between G. brachystegioides specimens from Cameroon and those from Gabon. Specimens from Cameroon often have larger leaflets compared to those from Gabon, but some specimens from Cameroon have leaflets just as small as those from Gabon. For example, the flowering specimen Mildbraed 7777 (K) from Cameroon has leaflets similar in size to the specimens from Gabon, but the number of pairs of leaflets on Mildbraed 7777 is 5 – 7 (– 8); similar to the other specimens from Cameroon.

Table 4. Number of leaves per number of pairs of leaflets, on fertile specimens of Gilbertiodendron brachystegioides from Cameroon and Gabon.

The number of pairs of leaflets is an important character for species differentiation in the Gilbertiodendron ogoouense species complex. However, since this is the only obvious difference between G. brachystegioides specimens from Cameroon and those from Gabon, and since there is considerable overlap, the Gabon specimens may not represent a different taxon. On the other hand some recent molecular studies show a general pattern of a genetic discontinuity that lies in Northern Gabon and seems to separate several Cameroonian populations or species from Gabonese ones (Peccoud et al. 2013; Hardy et al. 2014). Presently there are eight flowering specimens from Cameroon, but there are only three flowering collections from Gabon (Groulez 1109, Wilks 1086, 1600) and one from Equatorial Guinea (Wilks 3582). Before a decision can be made, more flowering specimens should be collected and studied, while a phylogenetic study may reveal if also in this case such a genetic discontinuity is present. A phylogenetic study by Estrella et al. (2014) suggests that the two Cameroon specimens Burgt 801 and Wieringa 2242 are conspecific and the two collections from Gabon Breteler 14983 and Wieringa 6226 as well; however, it is not clear from that study whether these four specimens represent one or two taxa.

13. Gilbertiodendron scutatum Wieringa & Estrella sp. nov. Type: Gabon, Nyanga, 27 km N of Igotchi, 31 Oct. 2003, J. J. Wieringa 5057 (holotype WAG! [WAG0102196 – 200], isotypes ALF, BENIN!, BHO!, BP, BR!, BRVU!, CANB!, CEPEC!, DAV!, E, GC!, GZU!, K!, LBV!, MA, MBM!, MO, SL!, UB!).

http://www.ipni.org/urn:lsid:ipni.org:names:77146142-1

Tree, to 47 m tall. Trunk straight, cylindrical, to 50 cm or more diam. Bark pale brown-grey with dropping flakes. Twigs sparsely puberulent to glabrous, hairs to 0.2 mm long. Stipules in pairs, free; reniform part persistent, green turning to brown, 15 – 48 × 10 – 40 mm, often longer than the internodes and therefore a pair of stipules often partly overlaps with the next pair, sparsely puberulent to glabrous both sides, hairs to 0.1 mm long; lanceolate part of stipule not seen. Leaves paripinnate, to 48 × 26 cm; petiole 5 – 12 mm long, 3 – 5 mm diam., puberulent to glabrous, hairs to 0.1 mm long; leaf rachis 9 – 35 cm long, puberulent to glabrous, hairs to 0.1 mm long, stipels absent; petiolules 1 – 3 mm long, puberulent to glabrous, hairs to 0.1 mm long. Leaflets papery, opposite, 5 – 9 (– 11) pairs, upper pair oblanceolate, middle pairs narrowly elliptic, lowest pair elliptic, middle pairs 7 – 15 × 1.5 – 4 cm (to 25 × 6 cm on juvenile trees); above smooth, somewhat glossy, glabrous; below sparsely puberulent to glabrous, hairs to 0.1 mm long, below lighter in colour, dull, densely papillose, with a granulate cellular structure (visible only by microscope); midrib below prominent and sparsely puberulent to glabrous, hairs to 0.1 mm long; 10 – 15 pairs of secondary veins; leaflet base attenuate to cuneate, oblique; apex acuminate and mucronate, acumen 0.5 – 1.5 cm long. Glands 0 – 2 per leaflet, at the proximal margin 10 – 20 mm from the apex and at the distal margin 2 – 4 mm from the petiolule. Inflorescence a cluster of 1 to several panicles, axillary or terminal, to 19 cm long, densely puberulous, hairs to 0.3 mm long, internodes to 30 mm long; lateral axes to 11 cm long, with 8 – 10 flowers per cm. Flowers: floral bract inserted at base of pedicel, caducous, ovate, 4 – 5 × 2.5 – 3 mm, densely puberulous outside, hairs to 0.3 mm long, puberulous inside, centre inside glabrous; pedicel 10 – 26 mm long, densely puberulous, dense light-coloured hairs to 0.1 mm long mixed with dense dark brown hairs to 0.4 mm long; bracteoles 2, elliptic, pinkish outside, white inside, 6 – 8 × 5 – 6 mm, densely puberulous outside, dense light-coloured hairs to 0.1 mm long mixed with dense dark brown hairs to 0.4 mm long; puberulous inside, centre inside glabrous; receptacle 1.5 mm high, 3 mm diam. at top, outside glabrous apart from two patches of hairs to 0.1 mm long at adaxial and abaxial side; sepals 5, white, narrowly triangular, abaxial sepal c. 6 × 3 mm, other sepals c. 5 × 2 mm, glabrous apart from a few short hairs on the margins of one or two of the sepals, apex acute; petals 5, glabrous, alternate to sepals; adaxial petal (not well seen) yellowish white, claw c. 4 mm long, blade bilobed, c. 8 mm high × 12 mm wide; the other 4 petals white, c. 5 × 1 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, glabrous, c. 9 mm long; anthers glabrous, c. 3 mm long; 6 staminodes, filiform, to c. 0.5 mm long, inserted on a staminodal tube c. 0.8 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 4 × 2 × 0.5 mm, 4 – 6 ovules, margins densely hirsute, hairs dark brown, to 0.8 mm long, sides glabrous; stipe 1 mm long; style white, 13 – 14 mm long, lower part sparsely hirsute, upper part glabrous, stigma capitate. Fruits oblong-rectangular, brown, dull, glabrous, 0 – 5-seeded, 22 – 26 × 8 – 10 cm, valve 3 – 5 mm thick, beak 1 – 3 mm long, sutures not winged; 3 – 3.5 longitudinal ridges running from the base to the apex, parallel to and at 0.3 – 4.5 cm distance to the upper suture. Seeds pale purple-brown, flat, to 42 × 42 × 7.5 mm. Seedlings: hypocotyl 5 cm long, epicotyl 13 cm long; first two leaves opposite, petiole and rachis 6 – 7 cm long, petiolules 1 mm, 2 pairs of leaflets 11 – 13 × 2.5 – 4 cm (in reality 3 pairs of leaflets, lowest pair reduced to < 3 mm long). Fig. 20; Map 15.

Fig. 20

Gilbertiodendron scutatum. A branch with inflorescences; B leaf and pairs of stipules; C leaflet lower surface; D floral bract; flower buds with short and long pedicel; E fruit. A – E from Wieringa 5057 (WAG). drawn by margaret tebbs.

Map 15

Distribution of Gilbertiodendron scutatum.

recognition. Gilbertiodendron scutatum is related to G. brachystegioides. The stipules are reniform, but flat; a pair of stipules is not strongly inrolled towards each other. The stipules are also larger in size, to 48 × 40 mm, and often longer than the internodes and therefore a pair of stipules often partly overlaps with the next pair; in G. brachystegioides the stipules are up to 30 × 20 mm and shorter than the internodes. The bracteoles are 6 – 8 mm long; not 5 – 6 mm long as in G. brachystegioides. The pods have 3 – 3.5 longitudinal ridges; not 1.5 – 2 longitudinal ridges as in G. brachystegioides.

distribution. Gilbertiodendron scutatum is known from Equatorial Guinea and Gabon (Map 15).

specimens examined. equatorial guinea. Monte Bata, 1 km N of road Bata – Niefang, near Santa Marta, fr. and seedlings, 7 Aug. 2003, Senterre 4278 (BRLU, K); Bicucbinii, entre Bata et Mbini, fr., 10 June 1998, Wilks 3565 (BRLU, WAG). gabon. Liby (Libreville), sterile, 25 Sept. 1952, Bernard SRF 904 (P); Moyen-Ogooué, 20 – 30 km NNW of Ndjolé, sterile, 29 Sept. 1994, Breteler 13075 (LBV, WAG); Ngounié, E of Yombi, on Fougamou – Mouila road, sterile, 18 Sept. 1990, Breteler 13967 (LBV, WAG); Mondah, sterile, 18 Oct. 1951, Estasse 580 (LBV); Mimongo distr., route Lébamba to Etéké, sterile, 14 May 1963, Hallé 5879 (P, WAG); Ogooué-Maritime, Loango National Park, sterile, 14 May 2005, Harris 8628 (E, WAG); Ogooué-Maritime, Monts Doudou, c. 40 km NE of Doussala, sterile, 11 April 2000, Sosef 1210 (LBV, MO, WAG); Fleuve Ogooué, Ndjolé, sterile, 1895, Thollon 85 (P); Nyanga, 27 km N of Igotchi, fl. & fr., 31 Oct. 2003, Wieringa 5057 (holotype WAG!, isotypes ALF, BENIN!, BHO!, BP, BR!, BRVU!, CANB!, CEPEC!, DAV!, E, GC!, GZU!, K!, LBV!, MA, MBM!, MO, SL!, UB!); same loc., sterile, 1 Nov. 2003, Wieringa 5063 (LBV, WAG).

habitat. Gilbertiodendron scutatum occurs in evergreen rain forest, at 0 – 600 m asl.

conservation status. Gilbertiodendron scutatum is assessed here according to IUCN criteria as Vulnerable A2cd+3cd (Table 1). Although the Extent of occurrence is 67.300 km², which is larger than the threshold of 20.000 km², Vulnerable is chosen because G. scutatum is a possible timber species and most of the 11 sites are located outside protected areas.

etymology. The species epithet of Gilbertiodendron scutatum refers to the large round stipules which have the appearance of a row of shields.

notes. A phylogenetic study by Estrella et al. (2014) places the type of Gilbertiodendron scutatum (Wieringa 5057) in the G. ogoouense species complex, thereby confirming the results of the morphological study. G. scutatum can be recognised by its large, round and flat stipules. The width of the stipules is usually larger than the length of the internodes, therefore a pair of stipules usually overlaps with its neighbouring pairs and the twig is normally not visible. The leaves and pods of G. scutatum resemble those of G. klainei. Both species have the same number of leaflet pairs, a papillose lower leaflet surface and the same number of longitudinal ridges on the pod. However, the stipules are clearly different: G. scutatum has reniform stipules; G. klainei has linear stipules.

14. Gilbertiodendron klainei (Pierre ex Pellegr.) J. Léonard (1954: 58); Saint Aubin (1963: 79); Aubréville (1968: 232 – 233); Aubréville (1970: 217 – 218).

Macrolobium klainei Pierre ex Pellegr.; Pellegrin (1920: 554; 1941: 508; 1949: 54). Baker (1930: 677). Syntypes: T.-J. Klaine 2936, 3100. Lectotype: Gabon, environs de Libreville, 25 June 1902, T.-J. Klaine 2936 (designated by Léonard 1957: 237, P! [P00391231], isolectotypes BR!, K!, WAG!).

Macrolobium klainei Pierre ex Harms (Harms 1922: 150), nom. illeg.

Tree, to 46 m tall. Trunk straight, cylindrical, to 120 cm diam. Twigs glabrescent to glabrous, hairs to 0.1 mm long. Stipules in pairs, free; reniform part absent; lanceolate part persistent but caducous on older twigs, 18 – 30 × 3 mm. Leaves paripinnate, to 50 × 22 cm; petiole 6 – 10 mm long, 3 – 5 mm diam., puberulent to glabrescent, hairs to 0.3 mm long; leaf rachis 9 – 40 cm long, puberulent to glabrescent, hairs to 0.2 mm long, stipels absent; petiolules 2 – 5 mm long, puberulent to glabrescent, hairs to 0.2 mm long. Leaflets coriaceous, opposite, 6 – 10 (– 11) pairs, oblanceolate, 7 – 18 × 2 – 5 cm, above smooth and glossy; below dull, lighter in colour, densely papillose, with a granulate cellular structure (visible only by microscope); above glabrous, below sparsely persistent puberulent, hairs appressed, 0.1 mm long; midrib above glabrous, flat or slightly channelled, below prominent and puberulent; 12 – 20 pairs of secondary veins; leaflet base attenuate to cuneate, slightly oblique; apex acuminate and mucronate, acumen 0 – 1 cm long. Glands 0 – 2 per leaflet, at the proximal margin 4 – 6 mm from the apex and at the distal margin 4 – 6 mm from the petiolule. Inflorescence a panicle, axillary or terminal, to 19 cm long, densely puberulous, dark brown hairs to 0.4 mm long, internodes to 50 mm long, lateral axes to 13 cm long, with c. 10 flowers per cm. Flowers fragrant, floral bract inserted at base of pedicel, caducous, ovate, 6 × 5 mm, densely puberulous on both sides, hairs to 0.3 mm long, centre inside glabrous; pedicel 5 – 12 mm long, densely puberulous, brown hairs to 0.4 mm long; bracteoles 2, elliptic, pink to purplish red outside, pale pink to cream-coloured inside, 8 – 10 × 6 – 7 mm, densely puberulous outside, brown hairs to 0.4 mm long; puberulous inside, centre inside glabrous; receptacle 1 mm high, 2 mm diam. at top, outside glabrous apart from one or two patches of hairs to 0.5 mm long at adaxial and abaxial side; sepals 5, white, glabrous, narrowly triangular, 4 – 5 × 1.5 mm, apex acute; petals 5, glabrous, alternate to sepals; adaxial petal whitish to yellowish white, claw 6 mm long, blade bilobed, 8 mm high × 12 mm wide; the other 4 petals white, 4 × 1 mm, apex acute; stamens 3, inserted alternate to the 4 small petals; filaments white, 15 – 17 mm long, glabrous; anthers 2 mm long, glabrous; 6 staminodes, filiform, to c. 0.5 mm long, inserted on a staminodal tube c. 0.8 mm long, tapering towards the top, encircling ¾ of the ovary stipe opposite the large petal; ovary light green, 4 × 1.5 × 0.5 mm, 6 ovules, margins densely hirsute, hairs dark brown, to 1 mm long, sides glabrous; stipe 1 mm long; style white, 12 – 13 mm long, lower part hirsute, upper part glabrous, stigma reddish, capitate. Fruits oblong-rectangular, brown, dull, glabrous, 0 – 5-seeded, 16 – 22 × 6 – 10 cm, valve 3 mm thick, beak 1 – 5 mm long, sutures not winged; 3 – 4 longitudinal ridges running from the base to the apex, parallel to and at 0.3 – 4 cm distance to the upper suture. Seedlings: hypocotyl c. 4 cm long, epicotyl c. 10 cm long; first two leaves opposite, petiole and rachis 5 – 6 cm long, petiolules 1 mm, 2 pairs of leaflets 12 – 14 × 4 cm (in reality 3 pairs of leaflets, lowest pair reduced to < 3 mm long). Fig. 21; Map 16.

Fig. 21

Gilbertiodendron klainei. A branch with inflorescence and stipule; B leaf; C leaflet lower surface; D floral bract; flower buds with short and long pedicel; E fruit. A – E from Klaine 2936 (K). drawn by margaret tebbs.

Map 16

Distribution of Gilbertiodendron klainei.

distribution. Gilbertiodendron klainei occurs in Cameroon and Gabon (Map 16).

Considering the currently known distribution, it is likely that Gilbertiodendron klainei also occurs in Equatorial Guinea. The species was previously reported from Equatorial Guinea (Velayos et al. 2010) but the specimen cited (Wilks 3565) belongs to G. scutatum.

specimens examined. cameroon. Duala, fl., June 1917, Fleury in Chevalier 33194 (P, WAG); Campo, fl., 1917, Fleury in Chevalier 33488 (P); South Province, TDC, fr., 5 Nov. 1991, Hallé 4206 (WAG); South Province, surroundings Camp Akok, fr., 26 Nov. 1991, Hallé 4275 (WAG); 15 km au SSE de Zingui, 50 km SE Kribi, fl., fr., 14 March 1968, Letouzey 9023 (P, YA); Près Makoure I, 3 km ENE Kribi, sterile, 4 Feb. 1974, Letouzey 12892 (K, P, YA); Bongola R., 30 km ESE Campo, fr., 13 Dec. 1979, Letouzey 15363 (P, YA); Near Kribi, Mont Elephant, fr., 19 Oct. 2002, Mackinder 489 (K,YA); 20 km ENE of Ebodie, Campo forest reserve, fr., Oct. – Nov. 1991, McKey C91 36 (18) (K); ENE of Kribi, 1 km E of Bidou I, Mbengué mt, fl., fr., 26 Feb. 1994, Wieringa 2350 (WAG); same loc., seedlings, 26 Feb. 1994, Wieringa 2352 (WAG). gabon. Ngounié, c. 20 km à l'ouest de Mandji, fr., 5 Aug. 2008, Dauby 1252 (WAG); Region des Lacs Avanga – Niondje, fl., Aug. 1949, Jourdan s.n. (P); Environs de Libreville, fl., 25 June 1902, Klaine 2936 (lectotype P!, isolectotypes BR!, K!, WAG!); same loc., fr., 17 Dec. 1902, Klaine 3100 (P); E of Cocobeach, R. Atia, fl., 6 Sept. 1948, Morel 55 (K, P); Ogooué-Maritime, Rabi-Kounga, 2 km S of Dianongo, fl. & fr., 6 July 1992, Wieringa 1239 (BR, K, WAG); Ogooué-Maritime, Rabi area, NE of Divangui, fl., 10 March 1994, Wieringa 2443 (BR, K, MO, P, WAG); Ogooué-Maritime, near Lac Bavinga, fr., 1 July 1992, Wilks 2595 (MO).

habitat. Gilbertiodendron klainei occurs in evergreen rain forest on well-drained soil, at 0 – 300 m asl.

conservation status. Gilbertiodendron klainei is assessed here according to IUCN criteria as Vulnerable A2cd+3cd (Table 1).

notes. A phylogenetic study by Estrella et al. (2014) places two of the flowering collections of Gilbertiodendron klainei (Wieringa 1239, 2443) in the G. ogoouense species complex. The placement of the species within the complex on morphological characters is less obvious, because the stipule differs from all other species in the complex (Table 2). However, the pod is similar to those of some of the other species in the complex.