Dimorphid

The dimorphids or heliomonads are a small group of heliozoa that are unusual in possessing flagella throughout their life-cycle. There are two genera: Dimorpha, a tiny organism found in freshwater, and the larger Tetradimorpha, which is distinguished by having four rather than two flagella. Bundles of microtubules, typically in square array, arise from a body near the flagellar bases and support the numerous axopods that project from the cell surface.

Dimorphids have a single nucleus, and mitochondria with tubular cristae. Genetic studies place them among the Cercozoa, a group including various other flagellates that form pseudopods.

Dimorphida