Althenia tzvelevii (Potamogetonaceae), a new species from SW Western Australia with bilocular anthers: morphology and molecular phylogenetic relationships

A new species Althenia tzvelevii is described from south western Australia. This is the second species after A. bilocularis described with bilocular anthers. Illustrations of plant morphology are provided by means of SEM images and habitat photographs are included. The phylogenetic relationships of the new species were investigated using five plastid DNA markers (matK, ndhF, rbcL, rpoB, and rpoC1), with published sequences augmented by several new sequences resulting in coverage of all described species in the genus. Althenia tzvelevii forms a clade with A. patentifolia and A. bilocularis and other relationships within the genus are clarified. The Western Australian Althenia hearnii is strongly supported as sister to the Eurasian-African clade composed by A. filiformis and A. orientalis.