Bryometopus pseudochilodon

Colpodid ciliate, length 40-80 microns. Shape also highly variable, but usually Chilodonella-like with bluntly pointed left anterior end and slightly concave ventral and convex dorsal side; rectangular or elliptical individuals are frequent. Right (ventral) side flat, left (dorsal) vaulted, especially postorally. Macronucleus ellipsoid, approximately 12 x 6 microns in vivo, in mid-body slightly left of median; many tiny nucleoli. 2-9 micronuclei, about 2.5 x 1.5 microns, attached to macronucleus, but not in definite position. Contractile vacuole surrounded by small collecting vesicles during diastole, its excretory pore in postoral suture at beginning of posterior third of cell. Cortex often rather rigid, slightly furrowed by somatic kineties, especially in left anterior portion. Cytoplasm colourless, crammed with tiny granules. Food vacuoles about 6 microns in diameter, contain bacteria, rarely small algae. Some vacuoles with small crystalline inclusions. Movement slow, usually gliding on substrate, occasionally rotating about longitudinal body axis. Cilia about 10 microns long, paired even on left side, cilia of each pair fused, but separate during silver carbonate impregnation. 20- 40 slightly spirally coursing kineties with cilia inconspicuously to distinctly condensed underneath adoral zone of organelles. Postoral suture indistinct to distinct. Along paroral membrane a short kinety comprising 4-7 dikinetids may be present. Oral aperture in anterior left quadrant of cell orientated at about 45 degrees to longitudinal body axis. Vestibulum broad-elliptical, deep spoon-like, right half of bottom distinctly striated by fibres originating from paroral dikinetids. Pharynx short, tubular, contains proximal fifth of adoral zone. Paroral membrane C-shaped, apparently composed of single, fused cilia or of di- or trikinetids. Adoral zone composed of about 15-30 organelles. Each organelle consists of 2 long and 1 slightly shortened row of basal bodies.