Genus: Flask-shaped; ciliation uniform and complete; slit-like cytostome not reaching the middle of body, without trichocyst-borders; two or more macronuclei (Kudo, 1966). Many contractile vacuoles along both dorsal and ventral edges (Carey, 1992). Species:

50 μm 100 μm 150 μm; x 400

31 μm 63 μm 94 μm; x 640

Amphileptus sp., cell body 310 μm long, 73 μm wide, two macronuclei ellipsoidal (slightly tapered at one end), 39 μm long, 19 μm wide, many contractile vacuoles aligned along both dorsal and ventral sides, x 200, x 400, x 640, Sayama Natural Park, Higashi-Murayama city, Tokyo, Japan, December 2001 by Y. Tsukii
100 μm 200 μm 300 μm; x 200

50 μm 100 μm 150 μm; x 400

31 μm 63 μm 94 μm; x 640

Amphileptus lanceolatus Dragesco, 1965: lanceolate in form; 120 μm long; pointed both anteriorly and posteriorly; no elongate neck region; trichocysts in the buccal region and also scattered throughout cytoplasm; mucocysts present; a macronucleus consisting of two spherical bodies with a intercalated micronuleus; a single contractile vacuole with satellite vacuoles (Carey, 1992).

Amphileptus inquieta (Biernacka, 1963): 170-200 μm long; with an elongate neck & rounded posterior; a row of four contractile vacuoles present laterally; two large spherical macronuclei (Carey, 1992).