Molecular phylogenetic study of Scleria subgenus Hypoporum (Sclerieae, Cyperoideae, Cyperaceae) reveals several species new to science

Abstract

Scleria subgen. Hypoporum (Cyperaceae), with 68 species, is the second largest subgenus in Scleria. Species of this pantropically distributed subgenus generally occur in seasonally or permanently wet grasslands or on shallow soils over sandstone or lateritic outcrops, less often they can be found in (open) woodlands. Previous studies established the monophyly of the subgenus, but the relationships between the species remained uncertain. In this study, DNA sequence data of 61 taxa of Scleria subgen. Hypoporum, where possible represented by multiple accessions from across their distributional range, were obtained for four molecular markers: the coding chloroplast marker ndhF, the chloroplast intron rps16 and the nuclear ribosomal regions ETS and ITS. Phylogenetic trees were constructed using Bayesian inference and maximum likelihood approaches. A species tree was constructed to summarise the results. The results indicate the existence of three sections: the monotypic, pantropically occurring, Scleria sect. Lithospermae, a new section from central and south America containing two species, and Scleria sect. Hypoporum, also pantropically distributed, containing the remainder of the species of the subgenus. Relationships in the latter section are not fully resolved. However, three or four different clades can be distinguished supported by some morphological characters. Our results indicate at least six new species in Scleria sect. Hypoporum. The new section and species are described in a taxonomical treatment. Their morphology is compared with (morphologically) closely related species.