Páramo Calamagrostis s.l. (Poaceae): An updated list and key to the species known or likely to occur in páramos of NW South America and southern Central America including two new species, one new variety and five new records for Colombia

Calamagrostis (syn. Deyeuxia), as traditionally circumscribed, is one of the most speciose genera from páramo grasslands of northwest South America and southern Central America and often dominates these high-elevation habitats. However, it remains difficult for researchers to accurately identify the species due to a lack of floristic treatments for most of the countries containing páramo, with the distribution of many species still very poorly known. In an effort to ameliorate this, we present an updated list and identification keys in English and Spanish (as electronic appendix) to the species of Calamagrostis s.l. known or likely to occur in the páramos of Peru, Ecuador, Colombia, Venezuela, Costa Rica and Panama. Fifty-four species are accepted, constituting 47 species currently circumscribed in Calamagrostis and seven species recently transferred to Deschampsia. Included within this are two new species, Calamagrostis crispifolius and Deschampsia santamartensis, which are described and illustrated. Both new species are found in páramos of the Sierra Nevada de Santa Marta (departamento Magdalena), on the northernmost tip of Colombia, with C. crispifolius also found in the Serrania de Perija on the border with Venezuela. Calamagrostis crispifolius differs from all other species of Calamagrostis s.l. by the presence of strongly curled, readily deciduous leaf blades, amongst numerous other characteristics including open inflorescences with generally patent branches, small spikelets, (3.5–)4–5.5 mm long, with sessile florets and a rachilla prolongation reaching from 2/3 to almost the apex of the lemma, with short hairs (< 1 mm long). Deschampsia santamartensis is similar to Deschampsia hackelii (=Calamagrostis hackelii) from austral South America but differs by its broad, rigid and erect, strongly conduplicate blades, 1.5–2.5 mm wide when folded, ligules of innovations 0.5–1 mm long, truncate or obtuse, ligules of upper flowering culms 3–4 mm long, broadly shouldered with an attenuate central point, ellipsoid spike-like panicle, 3–5.5 long × 1.5–2.5 cm wide, lemma surfaces moderately to lightly scabrous between the veins, lemma apex acute to muticous, entire, rachilla extension often absent and inside of the floret often with hyaline shiny sinuous trichomes to 1 mm long, emerging from the base of the ovary. We also present a broader circumscription of the common species Deschampsia podophora (=Calamagrostis podophora), with the new variety D. podophora var. mutica described and illustrated. Deschampsia podophora var. mutica principally differs from var. podophora by florets lacking awns and larger habit i.e. multiple taller culms with longer and wider leaf blades forming tussocks, with inflorescences often held within sheaths. Nomenclatural changes are presented, with Deyeuxia macrostachya newly synonymised under C. macrophylla and C. pittieri, C. pubescens and Deyeuxia pubescens newly synonimised under C. planifolia. Lectotypes are designated for Agrostis antoniana, Calamagrostis pisinna, Deyeuxia macrostachya and Deyeuxia sodiroana. We also document and give notes on five new records of Calamagrostis for Colombia: C. carchiensis, C. guamanensis, C. heterophylla, C. pisinna and C. rigida.