Portrait of Litonotus cygnus (Mueller, 1773) Foissner, 1995, a pleurostomatid ciliate. Markedly extensile, this individual is contracted. The slit-like oral aperture on the convex surface extends along most of the length of the neck region. Extrusomes are visible at the base of the neck region on the ventral surface. Two round centrally located macronuclei. Posterior contractile vacuole. Parallel kineties on right surface distinguish this genus from the similar Amphileptus in which longitudinal kineties converge on each other anteriorly and posteriorly. From freshwater pond near Boise, Idaho. Phase contrast.