Rhizochromulina is an unusual genus of marine heterokont

Heterokont

The heterokonts or stramenopiles are a major line of eukaryotes currently containing more than 100,000 known species. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which are a primary component of plankton...

 algae, with one species, R. marina. They are colored amoeboids with a single flagellum, and produce distinctive spindle-shaped zoospores. These have a cell structure typical of the axodine

Axodine

The axodines are a group of unicellular heterokont algae.They include pedinellids, silicoflagellates, and Rhizochromulinales.Other terms include "Actinochrysophyceae" and "Dictyochophyceae".-Characteristics:They characteristically have a...

s. Before it was studied in detail, Rhizochromulina was included among the superficially similar golden algae in the order Chrysamoebales, but these produce zoospore

Zoospore

A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some algae, bacteria and fungi to propagate themselves.-Flagella:...

s which are similar to flagellate golden algae in form.