Mycol. Res. 102 (11) : 1331–1337 (1998) 1331 Printed in the United Kingdom Fungi from Mauritius : Linocarpon species on Pandanus R. D U L Y M A M O DE1, P. F. C A N N O N2 A N D A. P E E R A L L Y3 " Faculty of Science, University of Mauritius, ReU duit, Mauritius # CABI Bioscience, Egham, Surrey TW20 9TY, U.K. $ University of Mauritius, ReU duit, Mauritius Four species of Linocarpon on Pandanus are described and illustrated. L. spathulatum and L. sulcatum spp. nov. have ascospores with grooved appendages and ascomata with eccentric ostioles. L. fasciatum sp. nov. is similar to L. pandanicola, but its ascospores lack appendages and the ascomata are smaller. A collection of L. elaeidis, not previously reported from Mauritius, has ascomata with distinct black papillate necks, in contrast to the type material which lacks these structures. Recent surveys of leaf litter fungi in the remaining native forest of Mauritius have revealed four species of Linocarpon. This genus was erected by Sydow & Sydow (1917) to include fungi on dead Pandanus leaves. Petrak & Deighton (1952), Walker (1980), and more recently Hyde (1988, 1992, 1997) have greatly contributed to the taxonomy of the genus. In his most recent study, Hyde (1997) recognized 23 species, and stressed the importance of ascospore appendage characteristics in species delimitation within the genus. The geographical distribution of Linocarpon is biased towards the tropics and subtropics. A large proportion of the species currently recognized occur in association with dead or dying tissues of Palmae and Pandanaceae, especially with host genera such as Calamus, Elaeis, Nypa, Livistona, Pandanus, Sabal and Raphia. Most species appear to be saprobes, although one is implicated as a pathogen of Sabal (Barr, 1978) and others may be present as endophytes within living tissue. This is the first report on Linocarpon from the Mascarene region. Four species are studied, all occurring on endemic Pandanus species. MATERIALS AND METHODS Field collections were made from Pandanus barklyi Balf. f., P. rigidifolius Vaughan & Wiehe, and P. palustris Thouars from Pe! trin Reserve and P. eydouxia Balf. f. from the Perrier Reserve, Mauritius. Samples were air-dried and microscopical studies were carried out partly in the Mycology Laboratory at the University of Mauritius and partly at IMI. Materials for microscopical studies were mounted in water, lactofuchsin, Melzer’s reagent or cotton-blue in lactic acid. Camera lucida drawings were made using an Olympus BH2 microscope and fungi were photographed with a Zeiss photomicroscope. All material was illustrated, and measurements made, from slides mounted in lactofuchsin. Material is deposited in the Mycological Herbarium of the University of Mauritius, with some duplicate specimens at IMI. Linocarpon elaeidis Petr., in Petrak & Deighton, Sydowia 6 : 312 (1952) (Figs 2, 5, 11, 12). Ascomata visible externally as scattered slightly raised greyish black areas 0±4–0±5 mm diam., with a pronounced black papilla and a central ostiole. In vertical section : 350–480 µm diam., 150–220 µm high, lenticular, the papilla 70–80 µm diam. and to 90 µm high, developing deep inside the leaf within the fourth layer of cells below the cuticle, the host cells above the ascoma variably melanized and often completely occluded in the central region around the ostiole, side and lower walls of ascoma light brown, made up of broken epidermal cells, with poor development of lateral fungal tissue. Paraphyses as long as the asci, 3–3±5 µm wide, hyaline, septate, branched, wider at the base. Asci 94–134¬8–10 µm, ³cylindrical, tapering slightly towards both ends, short-stalked, fairly thick-walled when young, becoming thinner at maturity, the apex rounded, with an apical ring ca 2±5 µm. diam. and 1 µm deep, eightspored. Ascospores arranged fasciculately, sometimes helically coiled, 72–90¬2–3±5 µm, filiform, ³uniform in width, slightly curved when released, hyaline, with refringent bands, the ends rounded, the base with a mucous pad ca 3 µm wide and 1 µm high. Host species : Pandanus rigidifolius. Also known from a number of species of Palmae (Calamus sp. Elaeis guineensis Jacq., Mauritia sp., and Raphia vinifera P. Beauv.) and Phenakospermum guianense Endl. (Strelitziaceae ; Hyde, 1992). Distribution : only known as a single collection from Mauritius ; recorded from Australia, Guyana and Sierra Leone by Hyde (1992). Fungi from Mauritius 1332 1 5 2 3 Fig. 5. Linocarpon elaeidis (Dulymamode P53). Asci, ascospores and paraphyses (bar, 20 µm). 4 6 Figs 1–4. Vertical sections through ascomata (bar, 100 µm). Fig. 1. Linocarpon spathulatum (holotype). Fig. 2. L. elaeidis (Dulymamode P53). Fig. 3. L. sulcatum (holotype). Fig. 4. L. fasciatum (holotype). The collection from Mauritius has a conspicuous melanized papilla with a central ostiole, which at first sight appears very different from authentic material (IMI 46620a, isotype) we have examined of L. elaeidis. This has shallowly domed black shiny ascomata with central non-papillate ostioles. The ascospores with flat mucous pads at one end are indistinguishable, however, and we consider that the development of the ostiolar papilla is either host-related or affected by environmental conditions. Specimen examined : Mauritius : Pe! trin Reserve, outside fence, on abaxial surface of a dead fallen leaf of Pandanus rigidifolius, 30 Apr. 1996, R. Dulymamode P 53 (mycol. herb. Univ. Mauritius ; IMI 375395). Linocarpon fasciatum Dulymamode, P. F. Cannon & Peerally, sp. nov. (Figs 4, 6, 15, 16). Etym. : from fasciatus, striped ; referring to the ascospores with refringent bands. Ascomata tholiformia, 0±7–0±9 mm diam., solitaria, fusca vel nigra, ostiolo centralo nigro ; 550–650 µm crassa, 140–170 µm alta, lenticularia. Paraphyses copiosae, 2–6 µm diam., hyalinae, septatae, Fig. 6. Linocarpon fasciatum (holotype). Asci, ascospores and paraphyses (bar, 20 µm). graduate angustatae, apicibus rotundatibus. Asci 110–178¬8–14 µm, cylindrici vel leviter angustati in ambibus apicibus, recti vel leniter curvati, brevistipitati, paulo crassitunicati in juventute, tenuitunicati ad maturitatem, apice rotundato et incrasso, annulo apicali 2–3±5 µm diam. et 1±5 µm crasso, octospori. Ascosporae multiseriatae, 84– 110¬2±5–3±5 µm, filiformes, graduate angustatae, hyalinae, tenuitunicatae, fasciatibus refringentibus. Appendices absunt. R. Dulymamode, P. F. Cannon and A. Peerally 1333 internally the ascomata bounded by half walls of the epidermal cells with variable amounts of tissue composed of vertically arranged dark brown thick-walled cells to ca 2 µm wide laterally, the cells often completely occluded by melanin deposits. Clypeus reduced to a few melanized cells around the ostiole. Paraphyses copious, 2–6 µm wide, hyaline, septate, as long as or longer than asci, wider towards the base, with rounded apices, probably in a mucous mass. Asci 110– 178¬8–14 µm, cylindrical but slightly tapered towards both ends, straight or slightly curved, short-stalked, rather thickwalled when young, thinner at maturity, the apex rounded and distinctly thickened, with an apical ring 2–3±5 µm wide and up to 1±5 µm deep, eight-spored. Ascospores arranged multiseriately, parallel or helical in the ascus, 84–110¬2±5– 3±5 µm, filiform, slightly wider in the middle and tapering gradually to the rounded apices, hyaline, often curved, thinwalled, with refringent bands caused by differential staining of the contents. Appendages absent. 7 Typification : Mauritius : Perrier Reserve, on abaxial and adaxial surfaces of dead fallen leaves of Pandanus eydouxia, 27 June 1996, R. Dulymamode P63 (mycol. herb. Univ. Mauritius – holotype ; IMI 375394 – isotype). Fig. 7. Linocarpon spathulatum (holotype). Asci, ascospores and paraphyses (bar, 20 µm). Host species : Pandanus eydouxia. Distribution : Mauritius ; only known from a single locality. 8 This species shares many ascomatal features of L. pandani (Syd. & P. Syd.) Syd. & P. Syd. but differs in sizes of the asci and ascospores. Asci are up to 178 µm long versus 140 µm for L. pandani (Hyde, 1992) while the ascospores are 84– 110¬2±5–3±5 µm compared to 62–80¬2–4 µm for L. pandani. L. fasciatum is also close to L. livistonae (Henn.) K. D. Hyde (also reported on Pandanus), but the former species has wider ascospores devoid of appendages. In addition, L. pandanicola K. D. Hyde (Hyde, 1997) has similarities to this species, but the ascomata of L. pandanicola are significantly larger, and shallowly conical rather than lenticular. Further, the ascospores of this species are shorter but contained in slightly longer asci (the range of measurements overlap) and they have mucous pads at each end of the spore, in contrast to those of L. fasciatum which lack these structures. Other specimen examined : same locality and host, 22 Jan. 1996, R. Dulymamode P5 (mycol. herb. Univ. Mauritius). Fig. 8. Linocarpon sulcatum (holotype). Asci, ascospores and paraphyses (bar, 20 µm). Ascomata visible on the substrate surface as dome-shaped structures 0±7–0±9 mm diam., solitary, greyish brown to greyish black in colour with a central black ostiolar dot. In vertical section : ascomata 550–650 µm wide, 140–170 µm high, lenticular, developing within the third (inner) layer of epidermal cells, breaking the cells along the mid region, Linocarpon spathulatum Dulymamode, P. F. Cannon & Peerally, sp. nov. (Figs 1, 7, 13, 14) Etym. : spathulatus, spoon-shaped, referring to the ascospores which are slightly swollen in the upper region. Ascomata tholiformia vel fere hemisphaerica, nigra vel atra, ostiolo centralo vel excentrico, 240–320 µm diam., 70–100 µm alto, lenticularia vel vix conica. Paraphyses copiosae, 3±5–4±5 µm diam., hyalinae, septatae, apicibus rotundatibus. Asci 110–170¬12–16 µm, cylindrici, apice truncato, in juventute crassitunicati, ad maturitatem tenuitunicati, annulo apicali ca 4 µm diam. et ! 1 µm crassi, octospori. Ascosporae multiseriatae, 66–89¬4–5±5(®6) µm, plus minusve rectae, hyalinae, fasciatibus refringentibus, versus apicem vix tumidae ad basim graduate angustatae, apicali rotundato, baso plus minusve Fungi from Mauritius 1334 9 11 10 12 Figs 9–12. Asci and ascospores of Linocarpon species. Figs 9–10. L. sulcatum (holotype). Fig. 9. Asci (bar, 20 µm). Fig. 10. Ascospore (bar, 10 µm). Figs 11–12. L. elaeidis (Dulymamode P53). Fig. 11. Asci (bar, 20 µm). Fig. 12. Ascospore ; note the basal mucous pad (bar, 10 µm). R. Dulymamode, P. F. Cannon and A. Peerally 1335 13 14 15 16 Figs 13–16. Asci and ascospores of Linocarpon species. Figs 13–14. L. spathulatum (holotype). Fig. 13. Asci (bar, 20 µm). Fig. 14. Ascospore (bar, 10 µm). Figs 15–16. L. fasciatum (holotype). Fig. 15. Asci (bar, 20 µm). Fig. 16. Ascospore (bar, 10 µm). Fungi from Mauritius 1336 crassitunicato, appendice basali ad 6 µm longo et ca 2 µm lato, cylindrico, sulcato. 107¬3–4 µm, plus minusve crassitunicato, obliquo, appendice basali 3–4±5¬1–1±5 µm, cylindrico, sulcato. Ascomata visible as dome-shaped to almost hemispherical structures 0±3–0±4 mm diam., greyish black to black, scattered, rarely fusing, ostiolar position variable, either central or to one side of the ascoma. In vertical section : 240–320 µm wide, 70–100 µm high, shallowly conical to lenticular, developing within the first or second layer of epidermal cells, splitting the cells apart, the upper and lower ascomatal walls consisting of melanized broken epidermal cells filled with often completely occluded fungal tissue, the lateral walls composed of compressed fungal cells with minimal melanin deposits. Clypeus poorly developed. Paraphyses copious, 3±5–4±5 µm wide, as long as the asci, hyaline, septate, rarely branched, wider towards the base. Asci 110–170¬12–16 µm, cylindrical, tapering abruptly to a truncate apex, short-stalked, rather thick-walled when young, thinner when mature, with an apical ring ca 4 µm diam. and ! 1 µm thick, eight-spored. Ascospores arranged multiseriately, 66–89¬4–5±5(®6) µm, cylindrical, often slightly swollen towards the apex and gradually tapering towards the base ; the base³truncate and thickened with a cylindrical appendage to 6¬2 µm in size, which has a groove extending from the base of the ascospore to the mid region of the appendage, the appendage tip rounded. Ascomata visible externally as slightly raised greyish black areas 0±5–0±8 mm diam., lighter in colour towards the illdefined periphery, with a dark elevated ostiole towards one end. In vertical section : 260–340 µm wide, 70–130 µm high, lenticular, developing within the first, second or third layer of epidermal cells, splitting apart the cells of that layer ; ascomatal wall light brown, consisting of an outer layer of broken melanized epidermal cells filled with dark brown thick-walled textura angularis and an inner layer of thick-walled dark brown compressed fungal cells. The lateral wall in the vicinity of the ostiole is composed of dark brown vertically arranged fungal cells, while the tissue of the opposite wall is made up of rather large dark brown angular cells. Clypeus absent, with a few layers of rather thin-walled melanized epidermal cells around the ostiolar canal. Paraphyses copious, 2–4 µm wide, as long as the asci, hyaline, septate, with rounded apices, wider towards the base, rarely branched. Asci 92–170¬12–20 µm, cylindrical to fusiform, tapering to a rounded to truncate apex, thickwalled when young, thinner at maturity, with a ring-like apical apparatus 3±5–4±5 µm wide and ca 1 µm deep, eight-spored. Ascospores arranged multiseriately, 76–107¬3–4 µm, ³straight in the ascus, slightly curved when liberated, hyaline with septum-like refringent bands, the wider upper half terminating in a rounded apex, the lower half gradually tapering to a ³ thickened slanted or flattened end, with a basal appendage 3–4±5¬1–1±5 µm in size, cylindrical with a groove extending from the apex of the spore to the mid region of the appendage, the tip rounded. Typification : Mauritius : Pe! trin Reserve, on abaxial surface of a dead fallen leaf of Pandanus palustris, 31 Aug. 1996, R. Dulymamode P 33 (mycol. herb. Univ. Mauritius – holotype ; IMI 375396 – isotype). Host species : Pandanus palustris Thouars. Distribution : Mauritius ; only known from one locality. This species resembles L. sulcatum (see below) in the shape and size of the asci and the presence of morphologically similar appendages. Differences are, however, quite marked ; the ascospores are shorter and wider, and slightly spathulate, and the ascomata are more visible externally as black domeshaped structures with a variable positioned ostiole. Of the 23 Linocarpon species reported previously, only L. clavatum K. D. Hyde, 1997) has such wide ascospores. The shape of these is distinctively clavate compared to the narrowly spathulate spores of L. spathulatum, and they are also shorter (41– 51¬4–5±5 µm) and widest at the centre. The ascospore appendage of L. spathulatum is the longest recorded for the genus. Linocarpon sulcatum Dulymamode, P. F. Cannon & Peerally, sp. nov. (Figs 3, 8–10). Etym. : sulcatus, grooved ; referring to the ascospore appendages. Ascomata tholiformia, ostiolo fuscato excentrico, 260–340 µm diam., 70–130 µm alto, lenticularia. Paraphyses copiosae, 2–4 µm diam., hyalinae, septatae, apicibus rotundatibus. Asci 92–170¬12–20 µm, cylindrici vel fusiformes, apice rotundato vel truncato, in juventute crassitunicati, ad maturitatem tenuitunicati, annulo apicali 3±5–4±5 µm diam. et ca 1 µm crassi, octospori. Ascosporae multiseriatae, 76– Typification : Mauritius : Pe! trin Reserve, on adaxial and abaxial surfaces of dead attached leaves of Pandanus barklyi, 8 Apr. 1996, R. Dulymamode P17 (mycol. herb. Univ. Mauritius – holotype ; IMI 375397 – isotype). Host species : Pandanus barkyli, P. rigidifolius. Distribution : Mauritius ; only known from one locality. Ascomata of this species are solitary with ostioles towards one end (as in Oxydothis) compared to the central ostiole of typical Linocarpon species. The ascospores are non-septate, in contrast to those of Oxydothis which are several septate and attenuated towards both ends (Hyde, 1994). The position of the ostiole has been used as a diagnostic character at different levels of classification ; Barr (1978) found this character to be helpful in differentiating families of the Diaporthales while Hyde (1994) stresses its importance at the generic level. We suspect that this character should be given a relatively low diagnostic weighting as it is likely to be significantly affected by host characteristics (Cannon, 1988). L. sulcatum has typical Linocarpon ascospores and we feel that its placement in this genus is justified in spite of the ostiolar position. Its ascospores are similarly shaped to those of L. palmetto (Ellis & Everh.) M. E. Barr, but are much longer with a prominent cylindrical appendage at the narrower end. The combination of ostiolar position, ascospore shape and size, and appendage features are unique to this species. R. Dulymamode, P. F. Cannon and A. Peerally Other specimens examined : Mauritius, Pe! trin, outside reserve, on abaxial surface of a dead fallen leaf of Pandanus barklyi, 22 Jan. 1996, R. Dulymamode P8 (mycol. herb. Univ. Mauritius ; IMI 375398) ; same locality, on abaxial surface of dead fallen leaf of P. rigidifolius, 30 Apr. 1996, R. Dulymamode P141 (mycol. herb. Univ. Mauritius ; IMI 375398). Dr. K. D. Hyde, University of Hong Kong, is thanked for his helpful comments on an early draft of the manuscript. The senior author thanks the University of Mauritius and the Tertiary Education Commission of Mauritius for funding these studies. REFERENCES Barr, M. E. (1978). The Diaporthales in North America. Mycologia Memoir 7, 1–232. (Accepted 28 January 1998) 1337 Cannon, P. F. (1988). Proposal to merge the Phyllachorales with the Diaporthales, with a new family structure. Systema Ascomycetum 7, 23–43. Hyde, K. D. (1988). The genus Linocarpon from the mangrove palm Nypa fructicans. Transactions of the Mycological Society of Japan 29, 339–350. Hyde, K. D. (1992). Fungi from palms. I. The genus Linocarpon, a revision. Sydowia 44, 32–54. Hyde, K. D. (1994). Fungi from palms. XIII. The genus Oxydothis, a revision. Sydowia 46, 265–314. Hyde, K. D. (1997). Additions to the genus Linocarpon (Ascomycetes : Hyponectriaceae). Botanical Journal of the Linnean Society 123, 109–131. Petrak, F. & Deighton, F. C. (1952). Beitrage zur Pilzflora von Sierra Leone. Sydowia 6, 309–322. Sydow, H. & Sydow, P. (1917). Beitrag zur Kenntnis der Pilzflora der Philippinen-Inseln. Annales Mycologici 15, 165–268. Walker, J. (1980). Gaeumannomyces, Linocarpon, Ophiobolus and several other genera of scolecospored ascomycetes and Phialophora conidial states, with a note on hyphopodia. Mycotaxon 11, 1–129.