Asymmetrical biraphid
Asymmetrical biraphid is one of nine morphology categories that we use to provide a visual aid in identification. These categories are artificial (not strictly evolutionary).
- Valves asymmetrical to apical axis OR asymmetrical to the transapical axis, or both
- Raphe system well developed
- Some genera possess apical porefields that secrete mucilaginous stalks
- Other genera secrete mucilagous tubes
