A new diatom genus Spargeria gen. nov. (Bacillariophyceae) from Xizang, China, and the description of two new species

During our investigation of diatom biodiversity in Xizang, two species exhibited unique morphological features discriminative from all previously known genera. Herein we describe these two species and describe as new the genus, Spargeria gen. nov. The new genus features narrow to wide rectangular valves, narrow valve mantles, filiform raphe branches that occur on the valve face only, terminal raphe fissures straight or slightly deflected to same side, bow-tie shaped central areas, chambered striae present on the valve face only, being absent from the mantle, wider striae near the axial area and very narrow near the margin, multiseriate striae with small and round areolae that are occluded externally. Comparatively, Spargeria zhuii sp. nov. has larger and robust valves, radiate striae, with one divergent stria near the apices, while Spargeria chenia sp. nov. is smaller, with narrow valves, striae slightly radiate in the middle, becoming convergent or parallel near apices. This new genus belongs to the family Pinnulariaceae, and it was compared and contrasted with other genera of this family. Our work suggests the need for continued studies to document the biodiversity of diatoms in Xizang.