Stylonychia ammermanni sp n., a new oxytrichid (Ciliophora : Hypotrichida)ciliate from the river Yamuna, Delhi, India

Stylonychia ammermanni sp. n. is widely distributed in the backwaters of th e Yamuna river of Delhi region. The cell measures about 135 x 50 mum and th e vegetative ciliature consists of an adoral zone of membranelles, two para llel undulating membranes, 18 frontal-ventral transverse cirri, one row eac h of right and left marginal cirri, four dorsal kineties, two dorsomarginal rows and three caudal cirri. The new species belongs to the S. mytilus-lem nae complex as judged by the morphology and division morphogenesis. A compa rison of various morphometric characters (size, shape and cirral pattern) w ith the other two described species of the complex reveals that S. ammerman ni sp. n. is distinct from them.