Family Amphimonadidae

Members of this family have a naked or loricate body with 2 equal flagella. There are several genera, mainly in fresh water.

Genus Spiromonas

Members of this genus have an elongate, spirally twisted body with 2 anterior flagella. They form spherical cysts in which division into 4 daughter individuals takes place. They live in fresh water. A synonym is Alphamonas Alexeieff.

Spiromonas angusta (Dujardin) Alexeieff lives in stagnant water or is coprophilic. It has also been found in bull sheath washings. It is spindle-shaped and about 10 u long.

Subclass Phytomastigasina

Members of this subclass typically have chromatophores and holophytic nutrition. Some are colorless but closely resemble other holophytic forms and are derived from them or from a common ancestor. A few are coprophilic and still fewer are parasitic. In each group the parasitic mode of life has undoubtedly arisen anew.

Order Chrysomonadorida

In this order the chromatophores, if present, are yellow, brown, orange or occasionally blue. The stored reserves include leucosin (presumably a polysaccharide) and lipids, but no starch. There are five suborders in the Chrysomonadorida, but only one of them, Euchrysomonadorina, contains forms of veterinary or medical interest. In this suborder the flagellate stage is dominant, and neither a siliceous skeleton nor a peripheral zone of coccoliths is present. This suborder contains 4 families, 2 of which contain parasitic or coprophilic species.