Capitate

Biseriate

 

Carinoportulae

Valve ends that are expanded into a rounded knob are termed capitate. Note that the shape terms subcapitate and subrostrate are quite close, and that many taxa can be described as possessing subcapitate to subrostrate ends. In general, capitate (and subcapitate) ends are more expanded than the most narrow point, while rostrate (and subrostate) ends are not more expanded than the most narrow point.

Citations

Barber, H.G. and Hayworth, E.Y. (1981). Guide to the Morphology of the Diatom Frustule. Freshwater Biological Association, 112 pp.

Image Credit: Sarah Spaulding

The headpole of Didymosphenia geminata is distinctly capitate.

Image Credit: Marina Potapova

The valve ends of Planothidium haynaldii are broadly capitate.

Image Credit: Marina Potapova

The ends of Achnanthidium dutheii are capitate.