Family: Body large, often a truncated ovoid.
Genus: Both ends blunt (Illustrated Guide, 1985). Similar to Condylostoma, but lacks undulating membrane; with ciliated peristomal field (How to know the protozoa, 1979). Ovoid and flattened in shape; somatic ciliation uniform; peristome, with a large conspicuous AZM on the left edge, spirals down to the cytostome; right edge lacks undulating membrane; a contractile vacuole posterior, connected to two longitudinal canals (Carey, 1992).
Species: 100-300 μm; macronucleus band-form (vermiform); with or without endosymbiotic Chlorella (How to know the protozoa, 1979).
Climacostomum virens isolated macronuclei, x 400, x 640, Aug. 7-13 1999, Vermont-Maine U.S.A., by Y. Tsukii
Climacostomum virens pellicle with endosymbiotic Chlorella, x 400, x 640, Aug. 7-13 1999, Vermont-Maine U.S.A., by Y. Tsukii