A new species of Discostella guiyangensis sp. nov. (Bacillariophyta, Stephanodiscales) from Guiyang, China: morphology and phylogeny

We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations, as well as molecular analysis. This species is morphologically distinguished from other species by a relatively smooth and slightly recessed central area with marginal striae of unequal lengths forked near the margin. Marginal fultoportulae and a single rimoportula are situated between every two costae or on the costae. Both morphological characters and the concatenated data of rbcL and SSU rDNA indicate that Discostella guiyangensis is a unique and new species. According to divergence time estimation analysis, Discostella guiyangensis is the oldest species among the Discostella species sequenced currently. In addition, we complement molecular data of Discostella asterocostata and Discostella stelligera.