Myxozoa

A phylum of the subkingdom Protozoa, characterized by spores of multicellular origin (usually with two or three valves), one to six polar capsules or nematocysts (each with a coiled hollow filament), and a one- to many-nucleated ameboid sporoplasm; parasitic in annelids and other invertebrates (class Actinosporea; subclass Actinomyxa) and in lower vertebrates (class Myxosporea). [myxo- + G. zoon, animal]

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Myxo·zoa (mik″so-zoґə) [myxo- + Gr. zōon animal] a phylum of chiefly histozoic or celozoic parasitic protozoa having spores of multicellular origin, with one or more polar capsules and one, two, or three, rarely more, valves, and usually found in fishes but also in amphibians and reptiles. It comprises two classes: Myxosporea and Actinosporea.