A parapleurolophocercous cercaria and a furcocercous cercaria from the freshwater gastropods of the Western Ghats.

Abstract

Two cercariae were recorded from freshwater snails, one each from Digoniostoma pulchella and Indoplanorbis exustus and named Cercaria sp. III Western Ghats n.sp. and Cercaria sp. IV Western Ghats n.sp. respectively. Cercaria sp. III Western Ghats n.sp. is distome, ocellate and pharyngeate with peculiar spines on the tail, belongs to the Parapleurolophocerca group. This cercaria has 10 pairs of penetration glands in two groups; thick walled large excretory bladder and 10 pairs of flame cells including a pair arising from the caudal excretory canal. Cercaria sp. III Western Ghats n.sp develops inside the sausage shaped redia. Developed cercariae were found outside the rediae, in the host tissue. The furcocercous cercaria, Cercaria sp. IV Western Ghats n.sp is elongate, non ocellate, pharyngeate and longifurcocercous with three crowns of spines beside mouth, three pairs of penetration glands, small excretory bladder and twenty-two flame cells including four flame cells in the tail stem. Asexual multiplication of the organism occurs inside the sporocyst in the hepatopancreas of I. exustus. The present paper reports two new cercariae with their intra-molluscan stages recovered from the snails of the Wayanad region of the Western Ghats, and their morphological and morphometric comparison with the related species to determine their systematic positions.