A new species of the New Zealand endemic grass Simplicia, Simplicia felix is described. The new species is segregated from and compared with Simplicia buchananii and Simplicia laxa. Simplicia felix occurs mostly in lightly shaded areas of seasonally dry alluvial forest. A distribution map and an assessment of the conservation status of the new species are presented. Genetic variation in the genus was examined, building on previously published work but including additional sampling. Analysis of nrDNA ITS and ETS and plastid trnL intron and trnL-F intergenic spacer sequences show Simplicia felix to be more closely related to Simplicia laxa than to Simplicia buchananii. NeighborNet analyses of AFLP profiles for the three species of Simplicia show each to consist of distinct clusters of genotypes well separated from each other.
Keywords: New Zealand flora; Poaceae; Simplicia; Simplicia buchananii; Simplicia felix; Simplicia laxa; conservation status; new species.