Morphology and molecular phylogeny of Mayamaea densestriata sp. nov. (Bacillariophyceae), a new terrestrial species from Henan Province, China

A new terrestrial diatom species, Mayamaea densestriata sp. nov., is described from moist agricultural soil in Henan Province, China. Morphologically, it exhibits the typical diagnostic features of the genus Mayamaea, including small, elliptical to linear-elliptical valves, areolae externally occluded with hymenes, uniseriate radiate striae, and a distinct sternum. M. densestriata closely resembles six congeners, including M. atomus, M. terrestris, M. fossalis, M. vietnamica, M. arida, and M. permitis, but can be clearly distinguished by its lanceolate axial area fusing with a transversely expanded central area, higher stria density, and a notably greater number of areolae per stria.

Phylogenetic analyses based on concatenated SSU rDNA and rbc L gene sequences strongly support the placement of M. densestriata within the genus Mayamaea. Furthermore, the overall topology also confirms the monophyly of Mayamaea, which is resolved as sister to a clade encompassing species of Pinnularia and Caloneis, thereby supporting its affiliation within the family Pinnulariaceae.