Reticulation within Sporobolus: recognition of two new sections, Acinifolii and Thellungia, and a new genus, Hyalolemma (Poaceae, Chloridoideae, Zoysieae, Sporobolinae)

We present a molecular DNA phylogeny utilizing four plastid regions (<i>rps16-trnK</i> spacer, <i>rps16</i> intron, <i>rpl32-trnL</i> spacer, <i>ndhA</i> intron) and the nuclear ribosomal internal transcribed spacer (ITS) region, investigating 123 species of subtribe Sporobolinae. We also aimed to assess the generic limits of <i>Sporobolus</i>, characterize possible subgeneric relationships among species in the genus, and identify hypothesized reticulation events. The core Bayesian tree, based on combined and congruent plastid and ITS regions, is well resolved, and 11 sections within a monophyletic <i>Sporobolus</i> are strongly supported. We describe a new genus, <i>Hyalolemma</i>, with two species and include a key; erect two new sections within <i>Sporobolus</i>, S.sect.Acinifolii and S.sect.Thellungia; and make three new combinations, <i>Hyalolemmacompactum</i>, <i>H.somalensis</i>, and <i>Sporoboluscollinus</i>. The names <i>Eragrostiscollina</i> Trin. and <i>Sporoboluscompactus</i> Clayton are lectotypified.