Guide to Encyonopsis thumensis
- Valves barely asymmetric to apical axis
- Apices barely protracted
- Axial area narrow
- Central area absent
- Raphe arched toward ventral margin
Valves are barely asymmetric,narrow lanceolate, and have barely protracted apices. The axial area is very narrow and the central area is absent. Striae are barely radiate to parallel.