Reinstatement and emendation of subfamily Micrairoideae (Poaceae)

Phylogenetic relationships among subfamilies of the well supported PACCAD clade of Poaceae remain uncertain. Several genera such as Micraira and Eriachne were considered incertae sedis in the most recent subfamilial classification of the grasses, but these two genera formed a well-supported clade in an analysis based on chloroplast and structural data. Another genus, Isachne, traditionally classified in the Panicoideae, also formed part of this well-supported clade. Despite strong molecular support for the clade, thus far no morphological synapomorphy has been found. Nevertheless, the strongly supported monophyly of this clade allowed us to suggest the recognition of a new subfamily within the PACCAD clade. Since there was already a name available, in this paper we propose the reinstatement and emendation of the circumscription of Micrairoideae. The reinstatement of Micrairoideae changes the acronym PACCAD to PACCMAD for this large clade of grasses.