Abstract Detail

Systematics Section/ASPT

Peichoto, Myriam Carolina [1], Welker, Cassiano A. Dorneles [2], Neffa, Viviana G. Solís [3].

Morphometric analysis of Schizachyrium beckii and allies (Poaceae - Andropogoneae) reveals two new species of Schizachyrium from South America.

Schizachyrium Nees belongs to the tribe Andropogoneae (Poaceae - Panicoideae) and includes ca. 60 species distributed in tropical and subtropical regions of the world, especially America and Africa. It is represented in America by ca. 30 species, 19 of which occurring in South America, from Colombia to Chile, Argentina and Uruguay. These taxa were divided into two groups based on morphological studies. One of them includes taxa with highly branched inflorescences and slender rachis internodes, flexuous at maturity, while the other group is characterized by sparsely branched inflorescences and thick rachis internodes, straight at maturity. Although the genus has been revised recently for South America, a group of specimens from Brazil and Paraguay with straight rachis internodes but usually highly branched inflorescences was found. They are morphologically similar to Schizachyrium beckii. Some of them also exhibit great morphological similarity with the type material of Andropogon luxurians, considered to date as a synonymous of S. sanguineum. The aim of this paper is to assess the morphological variation of these specimens to clarify their taxonomic identity. To accomplish this purpose, 37 exomorphological traits (15 qualitative and 22 quantitative characters) were analyzed using multivariate methods (cluster and principal coordinate analyses). The analysis included 27 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 different 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, and the other restrict to Brazil. Moreover, Andropogon luxurians proved as a distinct taxon from Schizachyrium sanguineum, being proposed the new combination of the name for the genus Schizachyrium. Description and illustrations of the two new species are presented, as well as a key to separate them from other morphologically related species.

Broader Impacts:

1 - Instituto de Botánica del Nordeste (UNNE-CONICET), Facultad de Ciencias Agrarias (UNNE), Sargento Cabral 2131, Corrientes, 3400, Argentina
2 - Universidade Federal do Rio Grande do Sul , Programa de Pós-Graduação em Botânica, Av. Bento Gonçalves 9500, Porto Alegre, RS, 91501-970, Brazil
3 - Instituto de Botánica del Nordeste (UNNE-CONICET, Facultad de Ciencias Exactas y Naturales y Agrimensura (UNNE), Sargento Cabral 2131, Corrientes, 3400, Argentina

Keywords:
Schizachyrium
new species
Brazil
morphometry.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PSY068
Abstract ID:460
Candidate for Awards:None