A NEW SPECIES OF Procamallanus (NEMATODA: CAMALLANIDAE) FROM Ailia coila (SILURIFORMES, AILIIDAE) FROM BARAK RIVER, CACHAR, ASSAM

A new species of parasitic nematode, Procamallanus (Spirocamallanus) ailiasus n. sp. is described from the intestine of the catfish, Ailia coila F. Helminton, 1822 (Siluriformes, Ailiidae) from Barak river, Cachar, Assam. Procamallanus (Spirocamallanus) ailiosus n. sp. differs markedly from all related species of the same fish hosts, in possessing a greater number (7+2+4) of caudal papillae in the male; presence of lesser number (9-10), 2–3 of them being incomplete (not extending from one lateral margin of capsule to other) of spiral ridges; barrel shaped with unequal cuticular expansion on dorsal and ventral side in female specimens, presence of peculiar two thick step like folds just above the basal ring and other morphological features. Parasitological examinations of some freshwater fishes of Barak River, Cachar, Assam was carried out during 2018 and 2019 and the study revealed, among other helminths, nematodes of the Family Camallanidae parasitizing the intestine of the catfish, Ailia coila. The new species is characterized by the presence of spiral thickenings, nerve ring and excretory pore position, length of spicules, number and arrangement of caudal papillae and shape of tail end. Abundance and prevalence is observed to be 1.5 and 50% respectively.