Morphometric analysis of Schizachyrium Nees (Poaceae-Andropogoneae) reveals two new species from South America

Abstract

Schizachyrium (Poaceae: Andropogoneae) includes ca. 60 species distributed in tropical and subtropical regions of the world. Although the genus has been revised recently for South America, a group of specimens with intermediate traits from Cerrado vegetation of Brazil and Paraguay was found. The aim of this paper is to assess the morphological variation of these specimens to clarify their taxonomic identity. Thirty-seven traits (15 qualitative and 22 quantitative characters) were analyzed using multivariate methods (cluster and principal coordinate analysis). The analysis included specimens from Central Brazil and Paraguay, as well as the type material of several morphologically similar species. The results obtained showed that the samples investigated form two clearly distinct groups from the species hitherto recognized. Based on this morphometric analysis, two new species of Schizachyrium from South America are proposed, one of them occurring in Brazil and Paraguay (Schizachyrium angustispiculatum), and the other restricted to Brazil (S. vallsii). Moreover, Andropogon luxurians proved as a distinct taxon from Schizachyrium sanguineum, being proposed the new combination of the name for the genus Schizachyrium (S. luxurians). Description and illustrations of the two new species and the new combination are presented, as well as a key to separate them from other morphologically related species.