Studies on the freshwater cercariae of Kerala VII. Echinostomatid cercariae

Abstract

Six species of Echinostomatid cercariae were found in freshwater molluscs of Kerala including three previously described forms, namely, cercariaEchinostoma revolution (Frolich 1802) Looss 1899, cercariaEchinostoma malayanum Leiper 1911 and cercariaEchinostoma ivaniosi Mohandas 1973. CercariaE. revolutum is redescribed with the report of a new intermediate host,Idiopoma dissimilis (Muller).Cercaria sp. VI Kerala n.sp. is characterised by 47 collar spines (5+7+23+7+5), three penetration glands on either side of the oesophagus, 65–85 upwardly directed spines dorsal to prepharynx and 18 pairs of flame cells in groups of three.Cercaria sp. VII Kerala n.sp. has 45 collar spines (5+6+23+6+5), two types of integumentary papillae, four pairs of penetration glands posterior to the ventral sucker and 21 pairs of flame cells in groups of three.Cercaria sp. VIII Kerala n.sp. possesses 51 collar spines (5+6+29+6+5), two types of integumentary papillae, two pairs of penetration glands posterior to the ventral sucker and 21 pairs of flame cells in groups of three. For all the three new species,Lymnaea luteola ftypica (Lamarck) acts as the first and second intermediate hosts.