Diatoms of North AmericaDiatoms of North America
Return to overview

Guide to Hannaea arcus

(Ehrenb.) R.M.Patrick 1966

Hannaea Arcus Guide
Credit: Pat Kociolek, Megan Otu
  1. Apices capitate to attenuate
  2. Dorsal margin convex
  3. Central swelling on ventral margin
  4. Rimoportulae 1-2

Apices are capitate to attenuate. The dorsal margin is highly arched and convex, while the ventral margin is concave with a swelling of the central area. The central sternum is distinct and narrow. A rimoportula is present near the valve ends and is often visible in the light microscope. Striae are parallel.