Description of Desmothoracids:
Circumscription: One subset of the group previously referred to as heliozoa. Amoeboid body giving rise to stiff pseudopodia (the heliozoan stage) located in an organic lorica, often stalked. Heliozoan stage produces biflagellated motile stage, which can then give rise to an amoeboid form with stiff but motile pseudopodia. Heterotrophic. Ultrastructural identity: Mitochondria with tubular cristae, microtubules in support of pseudopodia not in organized geometric arrays or in open hexagons, and no microtubule organizing centre is known. Many dictyosomes. Extrusomes concentric core and girdle (kinctocyst). Flagellated stage not studied in any detail. Synapomorphy: Tubulocristate protists with a heliozoan stage located in a fenestrated organic lorica.