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Guide to Surirella terryi

Ward ex Terry 1907

Surirella Terryi Guide
Credit: Jana Veselá
  1. Valves with slight twist in apical axis
  2. Valves linear, slightly heteropolar
  3. Valves large
  4. Porcae nearly as wide as fenestrae
  5. Axial area thickened, narrow

Valves are large, linear and slightly heteropolar with rounded cuneate ends. Valves are typically moderately, to distinctly, twisted along the apical axis. The valve length is much more variable (67–176 μm) than the valve width (23–35 μm). The axial area is very narrow and thickened. Valves are distinctly corrugated, with alternate to opposite porcae within a single valve. Alar canals appear about as wide as fenestrae, 16–25 in 100 μm.