Description of Archerella
Test: thick, rigid, compressed, with parallel sides, rounded ends; wall organic, three layers, no xenosomes, brown due to iron accumulation. Two pseudostomes at opposite ends, each elliptical, slightly thickened rim, very thin, short collar (at the limits of the resolution of the light microscope). Protoplast nearly fills test, green from zoochlorellae. Vesicular nucleus. Filopodia very thin, emerging from an internal ectoplasmic stalk at both apertures, rarely branching. Ecology: A. flavum is an important. character species of upper green parts of wet sphagnum. Two species; Type species: Archerella flavum Archer, 1877.