A morphology-based cladistic analysis of paspalum sect. Pectinata (Poaceae)

Abstract

A cladistic analysis using parsimony was carried out, including all six species of Paspalum sect. Pectinata plus an outgroup composed of six species of Paspalum subg. Ceresia, six additional Paspalum species belonging to different taxonomic groups, and two extrageneric taxa. The analysis was based on 65 morphological characters and was performed using both equal weights and implied weights. In all resulting cladograms, a well supported clade corresponding to Paspalum sect. Pectinata appears, with either P. ceresia or a clade comprising P. ceresia, P. stellatum, and P. eucomum as sister group. Within the Pectinata-clade P. lanciflorum emerges consistently as sister taxon to the remainder of the section, whereas the phylogenetic relationship among them is poorly resolved. The inclusion of Paspalum sect. Pectinata within a weakly supported subgenus Ceresia is confirmed. Incidentally, some doubt is thrown about the validity of the currently accepted circumscription of Paspalum subg. Ceresia, since the inclusion of P. humboldtianum and P. polyphyllum within it is not supported by our data.