Monoraphid

Mantle

Monotypic

Taxa that possess a raphe on only one valve are considered within the monoraphid group. Freshwater monoraphid genera include Cocconeis, Achananthes, Achnanthidium, Eucocconeis, Karayevia, Lemnicola, Planothidium, Platessa, Psammothidium and Rossithidium. The genus Nupela includes some monoraphid species and some biraphid species. On the Diatoms of the US website, Nupela is included in the biraphid group.

Image Credit: Marina Potapova

This image shows scanning electron micrographs of the rapheless valve and raphe valve of Psammothidium curtissimum. Species that possess such a heterovalvar combination are termed monoraphid.