Tryblionella Calida Guide
Credit: Pat Kociolek
  1. Valves slightly concave in the middle of the valve
  2. Apices protracted, narrowly rounded
  3. Narrow, indistinct fold present
  4. Transapical ribs distinct, 12-16 in 10 µm
  5. Fibulae number 7-9 in 10 µm

Valves are linear and slightly concave in the middle of the valve. The apices are narrow, protracte, and rounded. A narrow, indistinct fold runs along the longitudinal axis of the valve. The fold is barely undulate, or may not appear elevated or depressed from the main valve surface. Transapical ribs are distinct, but striae are difficult to discern.