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Diagnostic features

Valves identical, each possessing a raphe (genus is biraphid). Asymmetric in valve view, with one pointed end; the other bluntly rounded to pointed, but with the widest part of the valve often offset from the central area. Wedge shaped in girdle view. Attached to the bed by long mucilaginous stalks. Can form pale-yellowish blooms on unshaded stony streambeds, but considerably less abundantly than Didymosphenia.

Typical habitats

Stony bottom streams and rivers with good water quality


Kingdom Chromista
Phylum Ochrophyta
Class Bacillariophyceae
Order Cymbellales
Family Gomphonemataceae
Common name Diatoms