Ciencia · 2012

The genus Eragrostis (Poaceae: Chloridoideae) in northwestern South America (Colombia, Ecuador, and Peru): morphological and taxonomic studies

A morphological and taxonomic treatment of Eragrostis for northwest South America is given. The present revision intends to clarify the taxonomic and nomenclatural problems of the species of Eragrostis present in northwest South America. The classification, nomenclature, affinities, and macro and micromorphological variation of the genus are discussed. Forty-five morphological and micromorphological characters were selected for use in the descriptions and differentiation among the species. This study is based on the examination of herbarium specimens from AAU, AMAZ, ANSM, BA, BAA, BAB, BM, CA, CAUP, COAH, COL, CORD, CPUN, CTES, CUZ, ENCB, F, GB, GH, HAO, HUA, HUT, K, LE, LIL, LINN, LP, MA, MEXU, MICH, MO, NY, P, PSO, QCA, RSA, S, SGO, SI, TAES, UC, UPS, US, USM, UTC, W, and WIS, including the type specimens of most species studied. In addition, extensive field studies were performed to assess the diversity of the genus in this region of South America. Thirty-seven species are recognized in the study area (24 native and 13 introduced-naturalized); four of the species are cited for the first time for Colombia [Eragrostis atrovirens (Desf.) Trin. ex Steud., Eragrostis barrelieri Daveau, Eragrostis gangetica (Roxb.) Steud., Eragrostis soratensis Jedwabn.] and three for Peru [Eragrostis acutiflora (Kunth) Nees, Eragrostis bahiensis Schrad. ex Schult., and Eragrostis secundiflora J. Presl]. Eragrostis condensata (J. Presl) Steud. is endemic to Ecuador, while Eragrostis magna Hitchc. and Eragrostis pilgeri Fedde are endemic to Peru. Twenty-nine species are recorded in Colombia, 19 in Ecuador, and 26 in Peru. Keys for determining the species, descriptions, illustrations, geographical distributions, morphological and ecological observations, chromosome numbers, specimens studied, and synonymies are provided for all native and adventive species of Eragrostis in northwestern South America. Eragrostis lasseri Luces is placed as a synonym of Eragrostis ciliaris (L.) R. Br., and Eragrostis nigricans (Kunth) Steud. var. punensis Nicora is placed as a synonym of Eragrostis mexicana (Hornem.) Link subsp. mexicana. The lectotype for Eragrostis barrelieri Daveau is designated here. Eragrostis patula (Kunth) Steud. and Eragrostis unioloides (Retz.) Nees ex Steud. are excluded from the Colombian Flora since all specimens identified as Eragrostis patula are apparently misidentified and are usually referable to Eragrostis tenuifolia (A. Rich.) Hochst. ex Steud. A single specimen identified as Eragrostis unioloides as cited in the Flora of Antioquia (Colombia) was misidentified and it belongs to Chascolytrum juergensii (Hack.) Essi, Souza-Chies & Longhi-Wagner. (texto tomado de la fuente)

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