Stein, 1860
Body reniform, with distinct nose-like projection at anterior margin of oral cleft; with endosymbiotic methanobacteria. Laterally slightly to distinctly flattened. Mouth conspicuous in deep, transverse subapical oral cleft. Striated band ("transverse ribbon") inversely J-shaped on right side. Contractile vacuole in rear end. Resting extrusomes rod-shaped, about 7 µm long, forming distinct layer underneath pellicle. Ciliary rows 55-90 in number; ventral kineties extending from oral cavity backward; dorsal rows turning anteriorly, abutting oral cavity on anterior ventral and lateral sides. Oral ciliature formed by densely ciliated anterior portions of somatic kineties. Size in vivo 80-180 x 35-80 µm. Indicator of microaerobic or anaerobic conditions. Foissner et al. (1995) considered records from marine and brackish habitats very likely misidentifications and included the genus in Gymnostomatea.
Ref.: de Puytorac et al. (1985), Dragesco and Dragesco-Kernéis (1986), Sola et al. (1988), Foissner et al. (1995).