Mann and Stickle in Round, Crawford and Mann 1990      Category: Symmetrical biraphid
TYPE SPECIES: Cavinula cocconeiformis Mann and Stickle in Round, Crawford and Mann




Image Credit: Eduardo Morales, Ditmar Metzeltin

CLASS: Bacillariophyceae
  ORDER: Naviculales
    FAMILY: Cavinulaceae

  1. Valves linear-lanceolate to nearly circular
  2. Striae uniseriate, radial

Species of Cavinula are characterized by uniseriate, radial striae composed of round to elongate areolae. Valves are linear-lanceolate to nearly circular in outline. Internally, the central sternum is thickened, a feature visible in SEM. Externally, the proximal raphe is expanded, while the internal proximal raphe ends are straight. One or two chloroplasts are present in living cells, which are H-shaped in girdle view.

This genus is known from oligotrophic lakes and moist subaerial habitats across the United States. It includes the former Navicula cocconeiformis Gregory and its allies. The uniseriate, radial striae and the terminal raphe ends curve to opposite sides of the valve are just two characters that distinguish it from Navicula sensu stricto.

Cite This Page:
Spaulding, S., Edlund, M., Morales, E., and Metzeltin, D. (2009). Cavinula. In Diatoms of the United States. Retrieved October 01, 2014, from

Contributor: Sarah Spaulding | Mark Edlund | Eduardo Morales | Ditmar Metzeltin - January 2009