Guide to Gomphosphenia

Valves are cuneate, and may have linear or undulate margins. Valves are never bent or flexed. The raphe is straight and filiform. Externally, both proximal and distal raphe ends are straight. Internally, the proximal raphe ends terminate in branched, anchor shaped fissures. Internally, the distal raphe terminates in a helictoglossa. Striae are composed of foramina that may be obscured externally to give the appearance of ghost striae. Apical porefields, stigmata, septa and pseudosepta are absent in Gomphosphenia.

Gomphosphenia contains a small number of species. It was separated from Gomphonema by Lange-Bertalot (1995). Two species, G. grovei and G. lingulataeforme are widely distributed in benthic habitats of North America.