Body elongate cylindrical to fusiform, flexible, slightly contractile; oral region set off resembling a "head", often slightly bent but usually indistinct after impregnation. Oral bulge round, protruding slightly. Extrusomes 6-10 µm long, in vivo rod-like and fine, in oral bulge and scattered in body. Over 100 macronuclear nodules. Contractile vacuole in posterior end. Cortical granules colourless, in interkinetal rows. Specimens often yellowish-brown, very likely because of food vacuole contents. Somatic kineties 10-14 in number, longitudinal, in contracted specimens slightly spiralling, on "head" distinctly spiralled, densely ciliated. Dorsal brush typical for genus, composed of 4 rows of dikinetids. Circumoral kinety indistinct, very likely composed of 1 dikinetid at anterior end of each somatic row. Movement slowly gliding, rotating about main body axis when swimming in straight line. Size in vivo 120-300 x 20-30 µm.
Ref.: Kahl (1930), Lipscomb and Riordan (1990), Petz et al. (1995a).