Brachysira Serians
Credit: Paul Hamilton
  1. Valves lanceolate
  2. Striae slightly radiate to parallel
  3. Central area asymmetrically rounded
  4. Raphe straight at distal valve

Valves are lanceolate. The striae are slightly radiate to parallel. The axial area is linear and distinct. The central area is asymmetrically rounded. The raphe is positioned between two external longitudinal ribs. The raphe is straight with undifferentiated proximal fissures and deflexed T-shaped distal fissures. Areolae are rectanglular and elongated in the transapical axis.