A MOLECULAR PHYLOGENY OF THE SUBTRIBE SPOROBOLINAE AND A CLASSIFICATION OF THE SUBFAMILY CHLORIDOIDEAE (POACEAE)

Abstract . The classication of the subtribe Sporobolinae containing the following six genera is poorly understood: Calamovilfa (ve species endemic to North Amer i ca), Crypsis (11 species endemic to Asia and Africa), Psilolemma (one species endemic to Africa), Spartina (17 species centered in North Amer i ca), Sporobolus (186 species distributed worldwide), and Thellungia (one
species from Africa and Asia). The goal of this study was to reconstruct the evolutionary history of the Sporobolinae using molecular data with increased species sampling. Most species in this subtribe have spikelets with a single oret, one- veined (occasionally three- veined) lemmas, a ciliate membrane or line of hairs for a ligule, and fruits with free pericarps (modied caryopses). A phyloge ne tic analy sis was conducted on 161 species (250 samples), of which 134 species were in the Sporobolinae, using nuclear rITS (ribosomal internal transcribed spacer region) 1 and 2 sequences to infer evolutionary relationships. The maximum likelihood phylogram provides moderate support for a paraphyletic Sporobolus that includes Calamovilfa, Crypsis, Spartina, and Thellungia. The subtribe Zoysiinae (Urochondra and Zoysia) is sister to a highly supported Sporobolinae where the Psilolemma jaegeri−Sporobolus somalensis clade is sister to the remaining species of Sporobolus s.l. Within Sporobolus s.l. there are 15 major clades, of which 12 are strongly supported, two are moderately supported, and one is unsupported. A complete generic classication of the subfamily Chloridoideae is given.