Stephanocyclus gamma

Valves are cylindrical with a transversely undulate central area that occupies about half the valve diameter. One or two central fultoportulae are clearly visible in LM on the convex (raised) portion of the central area. The central area is otherwise colliculate with scattered nodules, or is unornamented. Striae are equal in length and multiseriate near the valve margins. Striae become uniseriate nearest to the valve center, where individual areolae are easily distinguished in LM.

Internally, alveoli are partially occluded by a central lamina, creating a distinct concentric ring (also called a shadow line) through the striae about one-third of the distance from the central area to the valve margin. Another concentric ring near the valve margin represents the distal internal occlusions of the alveoli (Håkansson 2002, Houk et al. 2010, Lowe 1981).

This page is dedicated to Rex Lowe on the occasion of his 70th birthday. Lowe published pioneering descriptions of the ultrastructure, ecology, and distribution of Cyclotella gamma over thirty years ago (Lowe 1981). More recently, Håkansson (2002) and Houk et al. (2010) have also published SEM descriptions and images. These images and descriptions were used above to describe features that cannot be seen in LM.