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Diagnostic features

Valves identical, neither possessing a raphe (genus is araphid). Wedge shaped in girdle view, often joined at valve faces to form fan-shaped colonies; club-shaped in valve view.  Costae (thickened transverse silica bands) can be seen in valve view as strips across the valve, and in girdle view as obvious structures beneath the valve face.  Chloroplasts golden-brown.

Typical habitats

Our records are from slow-flowing streams and springs


Kingdom Chromista
Phylum Ochrophyta
Class Bacillariophyceae
Order Fragilariales
Family Fragilariaceae
Common name Diatoms