Stylonychia ammermanni* sp. n., a New Oxytrichid (Ciliophora: Hypotrichida) Ciliate from the River Yamuna, Delhi, India

Summary. Stylonychia ammermanni sp. n. is widely distributed in the backwaters of the Yamuna river of Delhi region. The cell measures about 135 x 50µm and the vegetative ciliature consists of an adoral zone of membranelles, two parallel undulating membranes, 18 frontalventral transverse cirri, one row each of right and left marginal cirri, four dorsal kineties, two dorsomarginal rows and three caudal cirri. The new species belongs to the S. mytilus-lemnae complex as judged by the morphology and division morphogenesis. A comparison of various morphometric characters (size, shape and cirral pattern) with the other two described species of the complex reveals that S. ammermanni sp. n. is distinct from them.