Some new and known species of genera Tripylina Brzeski and Trischistoma (Nematoda) with a discussion on their relationships.

The paper deals with description of three new and two known species of Tripylidae Örley, 1880. Two new and a known species of the genus TripylinaBrzeski, 1963 while one new and one known species of Trischistoma are described. Tripylina ymyensis n. sp. is characterised by robust body; long, slender outer labial setae; stoma with thick cuticularised wall bearing a prominent dorsal tooth and two equal-sized posteriorly-placed subventral teeth; large ovoid coelomocytes with conspicuous, globular inclusions; simple vagina without cuticularised pieces and a long, curved tail with a U- or S-shaped turn, uniformly tapering into a narrow terminus. Tripylina valiathani n. sp. is characterised by moderately large body; plump, leaf-shaped outer labial setae; stoma with thick cuticularised dorsal wall bearing a prominent dorsal tooth and two small anteriorly-placed subventral denticles; large fusiform coelomocytes with tapering ends having fine granular inclusions; cuticularised vagina, a distinct prerectum and a stumpy, laterally curved tail with a blunt terminus. T. stramenti (Yeates, 1972) Tsalolikhin, 1983 has been reported for the first time from India. Trischistoma minor n. sp. is characterised by medium-sized body; with dense crystalloids and granular aggregates; low, flattened lip region; plump outer labial setae; slenderer post-labial cephalic setae lying closely posterior to outer labials; a post-uterine sac of one body diameter and a dorsally curved tail with ventral terminal turn. T. pellucidumCobb, 1913 forms the first report from India. The relationships of Tripylina and Trischistoma have been discussed.