Poa (Poaceae) of Colombia: A Taxonomic Revision

Le résumé fourni par la source

The grass genus Poa L. is widespread throughout temperate areas of the Andes, being a common constituent in the highly diverse but threatened high-elevation páramo grasslands of northwest South America. Knowledge of Poa from these páramo areas is very limited, however, with no comprehensive taxonomic treatments available for Colombia, which contains the largest area of páramo in the Neotropics and its surrounding countries. We present a taxonomic revision of Poa for Colombia accepting 15 species, including two recent combinations of Poa previously circumscribed in Aphanelytrum (Hack.) Hack. We describe a new species, P. colombiana Soreng & Sylvester, and a new variety, P. subspicata (J. Presl) Kunth var. glabrata Soreng & Sylvester, for Colombia and Ecuador. Poa colombiana is similar to P. aequatoriensis Hack. but differs in having lemmas pubescent on the keel and marginal veins, lemma apices weakly acute, flag leaf sheath margins fused 20%–38% their length, and anthers generally larger, > 1.2 mm long. Poa subspicata var. glabrata differs from P. subspicata s. str. in having glabrous lemmas. We provide two new records for Colombia of P. huancavelicae Tovar, and P. mucuchachensis Luces. Two species, P. orthophylla Pilg. and P. reclinata (Swallen) Soreng & P. M. Peterson, are considered endemic to Colombia. Poa soderstromii Negritto & Anton is placed as a subspecies of P. orthophylla, and P. leioclada Hack. is synonymized under P. mulalensis Kunth. The names P. annua L. var. exilis Tomm. ex Freyn, P. humilis Ehrh. ex Hoffm., P. infirma Kunth, P. leioclada, P. orthophylla, P. pauciflora Roem. & Schult., P. pratensis L. subsp. irrigata (Lindm.) H. Lindb., P. puberula Steud., P. pubiflora Benth., P. subcaerulea Sm., P. subspicata, and P. trachyphylla Pilg. are lectotypified, P. mulalensis is neotypified, and P. trachyphylla is epitypified. Four species are exotic and introduced from Europe: P. annua, P. infirma, P. pratensis, and P. trivialis L. We provide a key, descriptions, illustrations, distribution and habitat information, vouchers, and notes for each species.

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