Description of Paramyxea

Circumscription: Parasitic heterotrophic protists typically found in the digestive system of marine invertebrates where they feed by osmotrophy. Initial infectious cell is amoeboid. Paramyxeids are regarded as multicellular because the daughter cells formed by division of the infectious cell may be contained within the initial cell; these continue to develop into multicellular spores. With a complex process of nuclear and cellular division. Ultrastructural identity: Shape of mitochondria not confirmed. With a reduced (nine single microtubules) centriolar structure associated with the microtubules of the mitotic spindle; nuclear envelope disrupts during division. Synapomorphy: Tubulocristate protists, during spore development endogenous budding accompanies cell division. Composition: Several genera. Ref: Desportes and Perkins 1990.