Heliomonadida Explained

The Heliomonadida^[1] (formerly Dimorphida^[2]) are a small group of heliozoan amoeboids that are unusual in possessing flagella throughout their life cycle.

Classification

Genetic studies place them among the Cercozoa, a group including various other flagellates that form filose pseudopodia. This order has recently been placed into the new class of naked filose cercozoans called Granofilosea.^[1] There are two genera in this order:

• Heliomorpha, a tiny organism found in freshwater
• the larger Tetradimorpha, which is distinguished by having four rather than two flagella.

Morphology

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.

Notes and References

1. Bass D, Chao EE, Nikolaev S, etal . Phylogeny of novel naked Filose and Reticulose Cercozoa: Granofilosea cl. n. and Proteomyxidea revised . Protist . 160 . 1 . 75–109 . February 2009 . 18952499 . 10.1016/j.protis.2008.07.002 .
2. Nikolaev SI, Berney C, Fahrni JF, etal . The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes . Proc. Natl. Acad. Sci. U.S.A. . 101 . 21 . 8066–71 . May 2004 . 15148395 . 419558 . 10.1073/pnas.0308602101 . free .