Nordic Journal of Botany 30: 001–005, 2012 doi: 10.1111/j.1756-1051.2011.01310.x, © 2012 The Authors. Nordic Journal of Botany © 2012 Nordic Society Oikos Subject Editor: Arne Strid. Accepted 5 August 2011 Centaurea molesworthiae sp. nov. (Cardueae, Compositae) from southwest Spain E. López, J. A. Devesa and J. A. García Rojas E. López (bv2lonie@uco.es), Depto de Botánica, Ecología y Fisiología Vegetal, Facultad de Ciencias, Campus de Rabanales, Univ. de Córdoba, Ctra. de Madrid km. 396, ES-14071 Córdoba, Spain. – J. A. Devesa, Jardín Botánico de Córdoba, Avenida de Linneo s/n, ES-14004 Córdoba, Spain. – J. A. García Rojas, Barriada de la Paz 33, ES-11360 San Roque, Cádiz, Spain. Centaurea molesworthiae E. López, Devesa & García Rojas (Cardueae, Compositae), a new species from southwest Spain is described and illustrated. The morphological variability of C. molesworthiae and the three closest species, C. prolongoi, C. crocata and C. occasus is analyzed and discussed. The chromosome number (2n  40) of this new species is reported for the first time. The genus Centaurea comprises  250 species (Susanna and Garcia-Jacas 2007), distributed mainly in Europe, the Mediterranean region, and southwest Asia, of which about 90 species (more than 130 taxa) are found in the Iberian Peninsula (Devesa et al. unpubl.). In its classical conception, the genus is clearly paraphyletic (Susanna et al. 1995, Garcia-Jacas et al. 2000). Based on numerous phylogenetic studies of molecular characters (Bremer 1994, Gabrielian 1995, Susanna et al. 1995, Wagenitz and Hellwig 1996, Garcia-Jacas et al. 2000, 2001), the genus has recently been recircumscribed, involving profound restructuring (vide López and Devesa 2008), especially following the election of C. paniculata as new type for the genus (Greuter et al. 2001). Centaurea sect. Acrocentron (Cass.) DC. ( Centaurea subgen. Lopholoma (Cass.) Dobrocz) with ca 100 species (Font et al. 2002) is one of the most diverse sections of the genus. The species within this section mainly have a Mediterranean distribution, although there are also some Euro–Siberian representatives, such as C. scabiosa L. This group, previously treated as an independent genus by Cassini (1819), includes species with large and generally spinose capitula, and a “Centaurea scabiosa” pollen type (Wagenitz 1955). According to previously published studies (Font et al. 2002, 2009), the section is clearly monophyletic, and is represented in the Iberian Peninsula by ca 22 species, all of them endemic to this territory, except for C. collina L. (distributed in southwest Europe), C. clementei Boiss. ex DC. (Iberian–North African endemism), and C. scabiosa L. (Euro–Siberian species). Within the section Acrocentron, C. prolongoi Boiss. ex DC., C. crocata Franco and C. occasus Fdez. Casas, all endemic to the south–southwest of the Iberian Peninsula, are morphologically closely similar. They all have stems which are simple or sparsely branched, with few leaves. The plants have few capitula with yellow flowers and involucral bracts with a pectinate-fimbriate or pectinate-spinulose appendage, usually with an apical spinule or spine. When reviewing the material for the taxonomic treatment of the genus Centaurea for ‘Flora Iberica’ (coord. C. Aedo), we studied two herbarium specimens (no. 12906 COFC, no. 5513 GDA) with a certain resemblance to C. prolongoi but collected in the south of the Cadiz province (Spain), far away from the known distribution of that species. These plants had previously been identified with this binomial, but with some doubts as they were immature specimens and from acid soils (Garcia-Jacas and Susanna 1990, Garcia-Jacas 1992). Recent surveys conducted during the spring–summer 2010 revealed a population with abundant individuals in full bloom, living on siliceous substrates. Close study of the new collections revealed that they have a set of characters which allow us to refer them to a new taxon, described and discussed below. Material and methods The morphological and biometric studies were carried out on material of the new taxon and on similar species based on material collected by the authors and on material conserved Early View (EV): 1-EV see http://tinyurl.com/ctujsze Figure 1. Centaurea molesworthiae sp. nov. (A) habit, (B) node of a cauline leaf, (C) cauline leaf, (D) capitulum, (E) cross section of a capitulum, (F) outer involucral bract, (G) middle involucral bract, (H) inner involucral bract, (I) outer sterile flower, (J) inner hermaphrodite flower without pappus, (K) corolla of an inner hermaphrodite flower showing stamen filaments and one anther, (L) upper part of style and stigmatic branches, (M) achene, (N) pappus showing the inner row. Drawn by R. Tavera, Cádiz province, COFC 59475. in the herbaria COFC, COA, COI, GDA, LISU, MA, MAF and UNEX. The chromosomal study was performed on root meristematic cells. The antimitotic agent was 0.002 M 8-hydroxyquinoline (Tjio and Levan 1950), and we used as fixative a mixture of absolute alcohol and ferric acetate (3:1). The stain was alcoholic aceto-carmine (Snow 1963) applied for 24–48 h. The description of the chromosome morphology follows the terminology of Levan et al. (1964). Chromosome size is expressed by three values: the length of the longest chromosome, the length of the shortest chromosome and the mean length (with the standard deviation in parentheses). 2-EV Centaurea molesworthiae E. López, Devesa & García Rojas sp. nov. (Fig. 1) Caules aut simplices aut parum ramificati. Folia basalia rosulantia, lyrato-pinnatipartita aut lyrato-pinnatisecta, supra glabriuscula, subtus laxe araneosa. Capitula solitaria, pedunculata (nonnumquam pedunculis 70 mm). Involucrum ovoideum, basi rotundatum; eius bractearum involucralium appendix castanea vel saturate cinerea, erecta vel patens, triangularis atque valde vulneranti acumine ( longo: 5–12 mm) praedita et utrinque pectinatim 7–9 spinulosa, spinulis vel fimbriis lateralibus 1.5–4.0 mm, concoloribus aut infernis albescentibus. Flores flavidi. Achaenia 4.5–5.7  2.3–3.6 mm, obovoidea, matura  cinerea vel grisea. Pappus externus 8–11 mm. Type: Spain, Cádiz, Tarifa, Sierra de Ojén, the slope of ‘El Chivato’, 30STE6798, 19 Jun 2010, acid soils, J. A. García Rojas no. 59475 (holotype: COFC, isotype: no. 60482 COFC). Etymology The name of the species honors the English botanist Betty Eleanor Gusset Molesworth (1913–2002), a great expert on the flora of Cadiz. Description Perennial rhizomatous herb, unarmed except for the involucral bracts, green, subglabrous or with scattered unicellular arachnoid hairs, with punctuate glands. Stems up to 56 cm, erect, usually simple or branched only at the base, not or only slightly thickened under the capitula,  prismatic in section, longitudinally costate, non-alate, subglabrous or with scattered arachnoid hairs. Leaves up to 25  5 cm, green; the basal petiolate and arranged in a rosette (often dry at flowering time), the primordial ones ovate to ovate-lanceolate, entire, the adult ones lyratepinnatipartite or lyrate-pinnatisect, with lobules or segments ovate, ovate-lanceolate, or oblong-lanceolate, entire, mucronate, with margins entire or remotely denticulate, with pinnate primary venation and an abaxially prominent midrib, glabrescent; cauline leaves sessile, not decurrent, decreasing upwards in size, the lower pinnatipartite or pinnatisect with 1–5 pairs of lanceolate or linear-lanceolate lateral lobules (the terminal longer and only slightly wider), margins entire or remotely denticulate, adaxial surface glabrescent, abaxial surface glabrescent to sparsely araneose, the middle and upper leaves entire, narrowly lanceolate or linear-lanceolate. Capitula homogamous, discoid, with sterile outer flowers (with rudimentary androecium and occasionally a cypseloid) and hermaphrodite central flowers, solitary, terminal, with a peduncle up to 70 mm. Involucre 20–27  10–19 mm, ovoid, rounded at base. Involucral bracts imbricate, apparently arranged in 5–7 rows; middle bracts longer than the rest, ovate to ovateoblong, greenish (sometimes greenish–yellow at the margins) with longitudinal nerves very lightly marked or absent, araneose or loosely lanuginous, with a dark brown or chestnut-brown apical appendage, triangular, subglabrous or sparsely araneose, pectinate-spinulose, narrowly decurrent for much of the edges of the bract, with 7–9 pairs of lateral fimbriae or spinules, spinules 1.5–4.0 mm long, concolorous with the central part or lighter brown, and those of the decurrence whitish, terminating in an 5–12 mm long apical spine, coriaceous, very prickly, plano-convex in section, erect to patent; inner bracts 12–19 mm, linear or linear-lanceolate, glabrous, with margins narrowly hyaline along their entire length, apical appendage ovate or orbicular, cochleariform, scarious, entire, fimbriate or lacerate, brownish. Receptacle flat, with setaceous paleae. Corolla of the sterile flowers 20–30 mm, with whitish tube and limb pale yellow, with 4–5 lobules of 5–7 mm, unequal; that of the hermaphrodite flowers 24–32 mm, with tube 12–18 mm, whitish, slightly thickened at the base, and limb 13–14 mm, pale yellow, with 5 lobules of 5–7 mm  equal or one a little longer. Stamens with uniformly papillose filaments, papillae up to 0.2 mm, whitish; anthers 8.5–10 mm, yellowish or whitish above, with basal appendages 0.7–1.0 mm, membranaceous, often lacerate. Style whitish; stigmatic branches whitish or yellowish. Achenes 4.3–5.7  2.3–3.6 mm, homomorphic, all with pappus, obovoid, laterally compressed, truncate and with each ridge entire or finely denticulate, at maturity grayish or brownish, occasionally with some blackish patch, glabrescent to sparsely and inconspicuously sericeous-villous except sometimes around the hilum with erect white hairs; apical plate with a 0.1–0.4 mm long nectary, pentalobulate, white; hilum 0.6–1.2 mm, lateral-adaxial; with or without elaiosome. Pappus double, persistent; the outer with several rows of 8–11 mm long paleae, unequal, linear, serrate, white or brown; the inner with 1 row of 1.7–3.0 mm long paleae, flattened, smooth, laciniate or serrate above, erect and  connivent, at times (or with some of them) similar in size to those of the outer pappus. Chromosome number 2n  40 Spain. Cádiz. Tarifa, Sierra de Ojén, El Chivato, 28 Jun 2010, E. López and M. López no. 59474 (COFC). The basic chromosome number is x  10 (x  11 is also known in the section, Garcia-Jacas and Susanna 1992) and the chromosome number differs from that of the most affinate species, C. prolongoi (2n  20; Blanca and Cueto 1992, Hellwig 1994), although the same tetraploid level (2n  40, 4x) is known in other similar species of the section like C. crocata (Garcia-Jacas and Susanna 1992, Hellwig 1994). The chromosomal formula is 14 m  6 sm and the chromosome sizes are 8.05 2 (5.47  1.24) 2 3.26 mm. Habitat and distribution Clearings in scrub, scree, and fully exposed rocky slopes, in soils on siliceous substrates, between 200 and 650 m a.s.l., southwest Spain: Sierra de Ojén, near Tarifa, Cadiz province (Fig. 2). Similar species Centaurea molesworthiae belong in a group of species within section Acrocentron comprising C. prolongoi, C. crocata Figure 2. Locations of all studied material of Centaurea molesworthiae sp. nov., C. prolongoi, C. occasus and C. crocata. 3-EV Table 1. Main morphological features of taxonomic interest of the studied species. *apical spine of the appendage of middle involucral bracts. Taxon Character C. prolongoi C. crocata C. occasus C. molesworthiae Basal leaves lobules ovate or ovate-lanceolate lobules ovate or ovate-lanceolate lobules ovate-lanceolate or oblanceolate Apical spine* (mm) Corolla 1.0–4.5(8) yellow or yellowish– orange achene  pappus 20 0.5–3.5 yellow or yellowish– orange achene  pappus 40 lobules ovate-lanceolate, lanceolate, or linearlanceolate 2–7 pale yellow 5–12 pale yellow achene  pappus unknown achene  pappus 40 Achene/Pappus 2n and C. occasus, all endemic to the Iberian Peninsula and morphologically very similar. Nevertheless, C. molesworthiae is clearly differentiated in leaf morphology, the spinescent involucral bracts, the flower colour, and the relative size of achene and pappus (Table 1). Moreover, these species have disjoint distribution ranges (Fig. 2) and ecological preferences, and at least in the case of C. prolongoi and C. crocata, which are the only species as yet included in phylogenies with molecular characteristics, molecular data have also supported their segregation as separate species (Font et al. 2002). Centaurea molesworthiae is restricted to the southern Cadiz province and grows in acid substrates as C. crocata. Both taxa are tetraploid, but the latter is endemic to southern Portugal and differs from the former by having not pale yellow but yellow or yellowish–orange flowers, smaller spines of the involucral bracts, and achenes that are usually larger than the pappus (Table 1). By contrast, C. prolongoi and C. occasus are basophilic, and at least in the case of C. prolongoi, diploid. The two taxa also present biogeographic and morphological characteristics that support their taxonomic delimitation and differences with the new taxon (Table 1). Specimens examined Centaurea molesworthiae. Spain. Cádiz. Algeciras, Puerto del Cabrito, 6 Jun 1978, Guerra no. 12906 (COFC). Punta de Tarifa, 6 Jun 1978, Varo et al. no. 5513 (GDA). Tarifa, Sierra de Ojén, El Chivato, 19 Jun 2010, García Rojas no. 59475 (holotype: COFC) and no. 60482 (isotype: COFC); ídem, 28 Jun 2010, E. López and M. López no. 59474 (COFC) and no. 51401 (COA); ídem, 15 May 2010, Devesa et al. no. 59476 (COFC). Centaurea prolongoi. Spain. Granada. Cruz de Periquete, 31 May 1976, Marín et al. no. 10878 and 10980 (GDA); ídem, 3 Jul 1984, Quesada et al. no. 16613 (GDA). Loja, Sierra de Loja, 2 Jun 1989, García et Salinas no. 33678(GDA); ídem, 16 Jun 1982, Molero and Pérez Raya no. 23353 (GDA) and no. 443453 (MA); ídem, 16 Jun 1981, Molero et al. no. 15204 (GDA); ídem, 16 Jul 1976, Castroviejo and Valdés-Bermejo no. 443795 (MA); ídem, 20 Jun 1980, Valle et De la Guardia no. 221262 (MA); ídem, 22 Apr 1997, Navarro et al. no. 42510 (GDA). Sierra de Alhama, Zafarraya, Jul 2007, Calvo no. 773483 (MA). Sierra Tejeda, La Maroma, 12 Jul 1981, Blanca et Cueto no. 16612 (GDA). Málaga. Alhaurín de la Torre, 10 Apr 1998, Rubio no. 27301 (COA); ídem, 16 Jun 1998, Rubiono. 30032 (COA); ídem, 27 Apr 1998, Ruíz et Rubio no. 27302 (COA). Churriana, without date, Laza no. 4182 and 4183 (GDA). Coín-Mijas, 21 May 1999, Nydegger no. 692396 (MA). Cómpeta, 7 Jul 1973, Cabezudo and Valdés no. 239535 (MA); without date and collector no. 1123 (UNEX). Estepona, 4-EV Sierra Bermeja, 18 Jul 1975, Fernández Casas no. 394230 (MA); ídem, Jubrique-Igualeja, 7 Aug 1996, Hernández and Vivero no. 27761 (COA); ídem, Los Reales, 22 Jul 1993, Lora et al. no. 39561 (COA); ídem, 6 Aug 1996, Hernández and Vivero no. 27762 (COA); ídem, 22 Jul 1993, Lora et al. no. 39561 (COA). Frigiliana, 2 Jun 1931, Ceballos no. 135954 (MA). Mijas, Sierra de Almijara, 24 May 1979, Curel et Domínguez no. 43237 (COFC). Mijas, Sierra de Mijas, 17 Jul 1975, Fernández Casas no. 411248 (MA); ídem, 3 Jun 1845, Willkomm no. 135692 (MA); ídem, 8 Jul 1982, Nieto no. 9994 (COA); ídem, May, Colmeiro? no. 135956 (MA); ídem, May 1873, without collector no. 135961 (MA). Monda, 4 Jun 1952, Vicioso no. 246626 (MA). Monda-Ojén, 19 Apr 1977, Casaseca et al. no. 208060 (MA). Nerja, 2 Jul 1919, Estramera no. 135953 (MA). Ojén, Sierra Blanca, 28 Jun 1980, Jacquemoud and Jeanmonod no. 14509 (GDA) and no. 222946 (MA); ídem, 21 Jul 1993, Lora et al. no. 45926 (COA); ídem, Ventorrillo del Puerto de Ojén, 18 Jun 1972, Domínguez et al. no. 139961 (GDA). Sierra Almijara, 14 Jun 1919, Gros no. 135948 (MA); ídem, 23 Jun 1935, Laza no. 135949 (MA); ídem, 15 Jul 1936, Laza no. 135951 (MA). Sierra Blanca and Monda, 22 May 1966, Borja and Rivas Goday no. 187202 (MA). Sierra Blanquilla, Yunquera, 18 Jun 1919, Gros no. 135959 (MA). Sierra de Alfarnate, 26 Jun 1919, Gros no. 135952 (MA). Sierra de Enmedio, Cómpeta-Frigiliana, 4 Jun 1979, Blanca no. 5655 and 5656 (GDA). Sierra de Marbella, 12 May 1919, Gros no. 135960 (MA). Sierra de Marchamonas, 24 Jul 1909, Diez Tortosa no. 4179 (GDA). Sierra de Yunquera, 10 Jul 1890, Reverchon no. 135858 (MA). Sierra Palmitera, 23 May 1972, Sañudo et al. no. 198886 and 393372 (MA); ídem, 24 Jun 1976, Cabezudo and Valdés no. 216087 (MA). Tolox, Sierra Parda, 12 Jun 1932, Ceballos no. 135957 (MA). Sierra Tejeda, Jun 1914, Gross no. 135955.2 (MA); ídem, Canillas de Albaida, Jun 1913, Gros 135955 (MA); Cortijo del Alcazar, 3 Jul 1994, Cebolla et al. no. 592487 and 593207 (MA). Tolox, Sierra de Tolox, 4 Jul 1973, Cabezudo and Valdés no. 13962 (GDA) and no. 239527 (MA). Villanueva del Rosario, Sierra de los Camarolos, 2 Jun 2009, E. López and M. López no. 46215 (COA). Yunquera (Junquera), 10 Jul 1930, Vicioso no. 135958 (MA). Centaurea crocata. Portugal. Algarve. Monchique, Moinho do Peso, Jul 1924, Palhinha no. 135964, 474595 (MA) and no. 56949 (MAF); ídem, Serra da Brejeira, 5 Jul 2007, Pujadas et al. no. 46855 (COA); ídem, Sierra de Monchique, 27 Jun 1996, Fernández Casas and Souto Metelos no. 593211 and 625885 (MA); ídem, Jun 1849, Welwitsch no. 24325 (COI). Nave Redonda-Monchique, Jul 2003, Devesa and E. López no. 30305 and 30306 (COFC). Sao Marcos da Serra-Monchique, Fonte da Moreira, 29 May 1996, Carrasco et al. no. 588740 (MA). Sierra de Monchique, Barranco de Maceira, 29 May 1979, Beliz and Guerra no. 240205 (MA); ídem, Barranco de Pisoes, 28 Apr 1945, Silva et al. no. 4181 (GDA) and no. 135966, 240201 (MA); ídem, Casais-Marmelete, Aguas Belas, 15 Jun 1978, Beliz and Guerra no. 240203 (MA); ídem, Fóia, 8 Jun 2001, Morales et al. no. 045023 (GDA); ídem, Foia-Madrinha, Beliz and Guerra no. 240207 (MA); ídem, Monchique, Malhoes, 31 May 1979, Beliz and Guerra no. 240206 (MA); ídem, Monchique-Saboia, 17 Jun 1978, Beliz and Guerra no. 240204 (MA) and no. 4113 (UNEX); ídem, Odemira, Portela dos Caibros, 1 Jun 1964, Beliz and Cadete no. 240202 (MA). Baixo Alentejo. Cercal, 18 May 1962, Rainha no. 24323 (COI); ídem, Milfontes, 27 Jun 1996, Fdez. Casas et Souto Metelos no. 593210 and 625884 (MA); ídem, Santiago do Cacém, 9 Jun 1960, A. Fernandes et al. no. 24326 (COI). São Luis, Jun 1917, Ricardo Jorge no. 39237 (LISU). Odemira, Jun 1917, Ricardo Jorge no. 135964 (MA) and no. 24324 (COI); ídem, Sobreiral, Vale Ferro, 13 Jun 1984, Beliz and Guerra no. 4114 (UNEX). Vila Nova de Milfontes–Cercal, Apr 1886, Daveau no. 39235 and 39236 (LISU). Centaurea occasus. Portugal. Algarve. Faro, Loulé, 12 Apr 1994, Pinto Gomes no. 151381 and 151388 (MAF); ídem, 27 Aug 1994, Pinto Gomes no. 151380 (MAF); ídem, 28 Apr 1995, Pinto Gomes no. 151386 and 151387 (MAF); ídem, 9 May 1995, Pinto Gomes no. 151384 (MAF); ídem, 25 May 1995, Pinto Gomes no. 151378 (MAF); ídem, Malhão, 10 May 1995, Pinto Gomes no. 151382, 151383, 151385 and 151389 (MAF); ídem, Guelhim, 10 May 1995, Pinto Gomes no. 151379 (MAF); ídem, 26 Jun 1996, Fernández Casas and Souto Metelos no. 158056 (MAF). 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