taxonID	type	description	language	source
03DD8791FFC4FFF4BFB7FD4FFB9CFD7B.taxon	materials_examined	Representative specimens examined: — SEYCHELLES. Curieuse, G. Cusset & B. Jeune 290 (K), 27 June 1974; D. Vesey-Fitzgerald 5436 (K), 17 January 1987; Mahé, J. Procter 4468 (K); Mahé, Cascade, H. P. Thomasset 171 (K), February 1900; Copolia, B. Senterre & E. Henriette 7107 (SEY, P, GENT), 14 August 2014; Montagne Palmiste (= Bernica), S. A. Robertson 2521 (SEY, K), 20 January 1978; Pérard, B. Senterre & E. Henriette 7116 (SEY), 11 December 2014; Praslin, R. Alluaud s. n. (K), 09 June 1892; Midlands, D. Vesey-Fitzgerald 6117 (K), 9 January 1938; Silhouette, Mont Pot à Eau, B. Senterre & J. Gerlach 5294 (SEY, P, GENT), 18 March 2008; B. Senterre & C. Morel 7108 (SEY, P, GENT), 24 September 2014.	en	Henriette, Elvina, Larridon, Isabel, Morel, Charles, Goetghebeur, Paul, Senterre, Bruno (2015): Revision of the genus Costularia (Cyperaceae: Schoeneae) for the flora of the Seychelles, including the rediscovery and resurrection of a rare endemic species. Phytotaxa 231 (1): 31-41, DOI: 10.11646/phytotaxa.231.1.3, URL: http://dx.doi.org/10.11646/phytotaxa.231.1.3
03DD8791FFC4FFF4BFB7FD4FFB9CFD7B.taxon	distribution	Distribution: — Endemic to the Seychelles. Widespread on the main granitic islands (Curieuse, Félicité, Mahé, Praslin, Silhouette).	en	Henriette, Elvina, Larridon, Isabel, Morel, Charles, Goetghebeur, Paul, Senterre, Bruno (2015): Revision of the genus Costularia (Cyperaceae: Schoeneae) for the flora of the Seychelles, including the rediscovery and resurrection of a rare endemic species. Phytotaxa 231 (1): 31-41, DOI: 10.11646/phytotaxa.231.1.3, URL: http://dx.doi.org/10.11646/phytotaxa.231.1.3
03DD8791FFC4FFF4BFB7FD4FFB9CFD7B.taxon	biology_ecology	Ecology: — From sea level to the highest summits (ca. 900 m elevation; Fig. 2), typically dominant in the herbaceous fringes of inselbergs, but also colonizing actively the degraded soils in the lowland belt, for example on Praslin and Curieuse. Conservation: — Least Concern according to IUCN Red List (2014). Vernacular name: — This plant is known locally as “ Lerb razwar ”, which means ‘ razor herb’, due to the very sharp leaf margins. Taxonomic note: — Costularia hornei is endemic to the Seychelles where it represents the western limit of distribution of the subgenus Lophoschoenus (with tristichous leaves). It was first recorded there under a name misapplied by Baker (1877: 417, as Asterochaete elongata), who had seen only the specimen from the Seychelles (Horne 626), and provided a description based on the latter (for a complete description see also Kükenthal 1939 a: 27). Nevertheless, the true Asterochaete elongata, currently treated as Costularia melicoides (Poiret in Lamarck & Poiret 1806: 273) Clarke (1908: 48) (Type: REUNION. du Petit-Thouars s. n. (P- 02284597!, P- 00552880! )), is clearly a species of the subgenus Costularia, with distichous leaves, restricted to the Mascarenes. Costularia hornei differs from most other species in the subgenus Lophoschoenus by having the rachilla elongated and curved (Kükenthal 1939 a: 27). A second variety of that species, named Costularia hornei var. rectirhachilloidea, was proposed by Kükenthal (1939 a: 28) based on the rachilla internodes being short and straight (not elongated and curved as in the type variety) and on the glumes being of similar length (the basal ones reduced in the type variety). Nevertheless, current field explorations and study of a type specimen in Kew (Thomasset 171!) showed that the variety rectirhachilloidea does not represent a distinct variety but rather specimens at an early stage of spikelet development. Note that the basionym of Costularia hornei, i. e. Schoenus hornei, was published without description but it is nevertheless a valid name because it included an explicit reference to a previously published description (McNeill et al. 2012: Art. 38.1): Baker’s Asterochaete elongata was cited as a synonym, the specimen Horne 626 was cited and the epithet “ hornei ” was chosen to honour the collector. Although Schoenus hornei also included among the cited synonyms a previously validly published name, i. e. Cladium xipholepis, and could therefore be considered as an illegitimate name (McNeill et al. 2012: Art. 52), Clarke (1894) implicitly considered such synonymy as uncertain since he excluded the type of Cladium xipholepis (McNeill et al. 2012: Art. 52 and 7.5) which he considered as a “ young state of Baker’s Asterochaete elongata ”. Clarke also wrote on the specimen Horne 626 “ Schoenus hornei sp. nov. ”, in March 1891, and therefore it is clear that the name Schoenus hornei is typified by Horne 626 and that Clarke was making reference to the description given by Baker under Asterochaete elongata. Note that another syntype was cited by Clarke (1894), i. e. Wright 81, which we could not examine but which is clearly not the same sheet than the specimen Wright s. n. (type of Cladium xipholepis; ‘ s. n. ’ being sometimes an omission of a number).	en	Henriette, Elvina, Larridon, Isabel, Morel, Charles, Goetghebeur, Paul, Senterre, Bruno (2015): Revision of the genus Costularia (Cyperaceae: Schoeneae) for the flora of the Seychelles, including the rediscovery and resurrection of a rare endemic species. Phytotaxa 231 (1): 31-41, DOI: 10.11646/phytotaxa.231.1.3, URL: http://dx.doi.org/10.11646/phytotaxa.231.1.3
03DD8791FFC5FFF1BFB7FD10FD18FBFE.taxon	materials_examined	Representative specimens examined: — SEYCHELLES. Mahé: Copolia, 500 m elev., - 4.64916 ° S, 55.45778 ° E, 17 July 2014, B. Senterre & E. Henriette 7101 (GENT, P, SEY), 25 August 2006, M. Luceño & M. Guzmán 8406 ML (UPOS); Pérard, pentes nord-ouest, 821 m elev., – 4.64011 ° S, 55.43617 ° E, 17 March 2013, B. Senterre & E. Henriette 6558 (P, SEY), 19 May 2013, B. Senterre 6583 (P, SEY), 18 June 2013, B. Senterre 6586 (GENT, P, SEY), 26 July 2013, B. Senterre 6589 (GENT, P, SEY), 29 January 2014, B. Senterre & E. Henriette 6964 (GENT, P, SEY), 11 December 2014, B. Senterre & E. Henriette 7117 (SEY).	en	Henriette, Elvina, Larridon, Isabel, Morel, Charles, Goetghebeur, Paul, Senterre, Bruno (2015): Revision of the genus Costularia (Cyperaceae: Schoeneae) for the flora of the Seychelles, including the rediscovery and resurrection of a rare endemic species. Phytotaxa 231 (1): 31-41, DOI: 10.11646/phytotaxa.231.1.3, URL: http://dx.doi.org/10.11646/phytotaxa.231.1.3
03DD8791FFC5FFF1BFB7FD10FD18FBFE.taxon	distribution	Distribution: — Costularia xipholepis is endemic to the Seychelles and restricted to Mahé and has been found in only three localities all situated in the Morne Seychellois National Park: Congo Rouge (B. Senterre & T. Stévart, observation record, 20 July 2014: – 4.6512 ° S, 55.44126 ° E, 610 m elev.), Copolia (where specimens were also collected by M. Luceño & M. Guzmán in 2006, but identified as Costularia hornei) and Pérard (Fig. 2). It has been searched for in suitable sites on Silhouette (Mont Pot à Eau) and around Morne Blanc but was not found. Other localities that should be checked on Mahé include Glacis Sarcelles and Trois Frères.	en	Henriette, Elvina, Larridon, Isabel, Morel, Charles, Goetghebeur, Paul, Senterre, Bruno (2015): Revision of the genus Costularia (Cyperaceae: Schoeneae) for the flora of the Seychelles, including the rediscovery and resurrection of a rare endemic species. Phytotaxa 231 (1): 31-41, DOI: 10.11646/phytotaxa.231.1.3, URL: http://dx.doi.org/10.11646/phytotaxa.231.1.3
03DD8791FFC5FFF1BFB7FD10FD18FBFE.taxon	biology_ecology	Ecology: — This species is restricted to the herbaceous fringe of lower montane inselbergs. It has been observed from 500 to 821 m elev. but was more abundant on the site at the higher elevation, which corresponds to an altitudinal belt named the tree fern lower montane belt (Senterre 2011, Senterre & Wagner 2014, Senterre et al. 2009). At Copolia, it has a more patchy distribution, growing on rock crevices and along fissures where the soil is damp. In all sites, it grows in association with Costularia hornei. Conservation: — Costularia xipholepis is rare and highly localized, known from only 3 small sub-populations representing 3 localities, 1.4 to 2.4 km apart, separated from each other by unsuitable habitat (i. e. wet forests). The three sub-populations are within the Morne Seychellois National Park, appear healthy, with limited risks from invasive species. The area of occupancy (AOO) for the Congo Rouge population is 10 m 2, Copolia 6,000 m 2, and Pérard 20,000 m 2, totalling approx. 26,000 m 2 (0.026 km 2) and its extent of occurrence (EOO) was estimated at approximately 1 km 2. Both AOO and EOO fall within the limits of Critically Endangered status under criteria B. The total number of mature individuals is unknown but probably around a thousand. According to IUCN criterion B (EOO <5000 km 2, AOO <500 km 2, number of locations ≤ 5, and a projected decline of the quality of the habitat as a result of climate change (IUCN 2012), this species can be classified as Endangered (EN B 1 ab (iii) + 2 ab (iii )). Vernacular name: — Due to the rarity of Costularia xipholepis, the species did not receive a local name yet. Because of the remarkable distichous disposition of the leaves, very much fan-shaped, we propose to name it ‘ Lerb levantay’, meaning fan-shaped grass in Creole. Taxonomic note: — Among the known species of Costularia subgenus Costularia, only one presents some similarity with Costularia xipholepis, i. e. Costularia pantopoda (Baker 1885: 451) Clarke (1894: 658) var. baronii (Clarke 1894: 658) Kükenthal (1939 b: 67) (type: Baron 3316, K 000244885!), endemic to Madagascar. Both species have long leaves and hypogynous bristles much longer than the nut, with relatively few empty glumes, but C. xipholepis differs most obviously in its clearly stipitate nutlet (Table 1). The identity of Costularia xipholepis has been the subject of much confusion. It was initially described as Cladium xipholepis, a new species endemic to the Seychelles, by Baker (1877), based on the single specimen Wright s. n. (K). Nevertheless, later studies treated that specimen sometimes as belonging in Costularia subgenus Lophoschoenus (as a species synonym of Costularia hornei: Clarke 1894: 657; Summerhayes 1928: 394), and sometimes in Costularia subgenus Costularia (as a species synonym of Costularia melicoides: Kükenthal 1939 b: 72). Our rediscovery in the field of plants of Baker’s true Cladium xipholepis allowed us to collect new specimens with more developed spikelets and to correct important errors made in the original description of that species. It also allowed us to confirm the distichous position of the leaves, the absence of a midrib and to confirm diagnostic characters distinguishing it from the Mascarene C. melicoides. The latter is quite different from C. xipholepis, even at first sight, and can be distinguished by its much less robust habit, its basal leaf sheaths which are smooth (long ciliate in C. xipholepis), and its spikelets with the terminal flower sterile (fertile in C. xipholepis).	en	Henriette, Elvina, Larridon, Isabel, Morel, Charles, Goetghebeur, Paul, Senterre, Bruno (2015): Revision of the genus Costularia (Cyperaceae: Schoeneae) for the flora of the Seychelles, including the rediscovery and resurrection of a rare endemic species. Phytotaxa 231 (1): 31-41, DOI: 10.11646/phytotaxa.231.1.3, URL: http://dx.doi.org/10.11646/phytotaxa.231.1.3
