Taxonomic Revision of Paspalum Group Caespitosa (Poaceae, Panicoideae, Paspaleae)

Abstract

A taxonomic revision and nomenclatural update for Paspalum L., group Caespitosa are presented. The group Caespitosa consists of perennial species, usually rhizomatous, with culms simple, erect, inflorescences terminal, pauci-racemose, and spikelets mostly ellipsoid to ovoid or obovoid. It is distributed from the southern United States to northeastern Argentina, with several taxa concentrated in the Caribbean Islands. We recognize 13 species and three varieties (i.e., Paspalum acutifolium León, P. albidulum Henrard, P. bakeri Hack., P. blodgettii Chapm., P. caespitosum Flüggé, P. chacoense Parodi, P. divergens Döll, P. galapageium Chase var. galapageium, P. galapageium var. minoratum Chase, P. galapageium var. redundans (Chase) Delfini & Zuloaga, P. indecorum Mez, P. laxum Lam., P. ligulare Nees, P. molle Poir., and P. redondense Swallen), and designate lectotypes for three names. We propose a new synonym for P. ligulare and a new variety for P. galapageium, and provide updates on inferential lectotypifications (for seven names) and on inferential neotypification (for P. caespitosum var. longifolium). We then comment on four situations of uncertainty, and present new geographic analyses of the species. Illustrations, a key for the species, and additional comments on morphology of the group Caespitosa are also included.

Phylogenetic Relationships in the Group Caespitosa of Paspalum L. (Poaceae, Panicoideae, Paspaleae)

“…Data presented here greatly increased the sample of Caespitosa species analyzed and confirmed that this informal group as traditionally circumscribed (sensu [8,9,31]) is not monophyletic. An analysis of the different clades and relationships among species is discussed next.…”

“…In total, we added to the analyses 40 new accessions of the group Caespitosa and sampled 13 taxa (i.e., Paspalum acutifolium, P. bakeri, P. blodgettii, P. caespitosum, P. chacoense, P. galapageium, P. indecorum, P. laxum, P. ligulare, P. molle, P. pleostachyum Döll, P. redondense, and P. redundans; Table S1), considering species accepted and synonyms in the taxonomic treatment in ref. [31]. The nuclear ribosomal DNA ETS matrix and chloroplast DNA (cpDNA) ndhF and rpl16 matrices previously published in ref.…”

“…Caespitosa is one of these informal groups, and its species are distributed from the southern United States to northeastern Argentina, with six concentrated in the Caribbean and Mexico [1,8,9,30,31]. They are outstanding for their ability to tolerate extreme climatic stresses, such as prolonged droughts, floods, and saltwater [28].…”

“…In a complete and most recent revision of the group Caespitosa, ref. [31] , and P. redondense), characterized by including perennial plants, usually rhizomatous, with culms simple, erect, inflorescences terminal, pauci-racemose, and spikelets mostly ellipsoid to ovoid or obovoid [31].…”

“…We analyzed a total of 13 Caespitosa species considered to belong to this group, those treated in the taxonomic revision of ref. [31]. The relationships of Caespitosa taxa were herein discussed and related to morphological, anatomical, and ecological evidence.…”