Capillostrongyloides Ancistri sp. n. (Nematoda: Capillariidae) a new pathogenic parasite of aquarium fishes in Europe.

A new nematode species, Capillostrongyloides ancistri sp. n., is described from the intestine of aquarium-reared catfish Ancistrus dolichopterus Kner in Czechoslovakia. This fish is of South American origin and, therefore, C. ancistri sp. n. has probably been brought into aquaria in Europe from there. The parasite is characterized mainly by the structure of the male caudal end (presence of two large postanal papillae and the cuticular bursa supported by two caudal lobes), the length of a spicule (0.258-0.297 mm), the presence of a non-spiny spicular sheath, shape of the female end, structure of the stichosome (23-30 stichocytes present), and the size of the eggs. The species appears to be highly pathogenic to aquarium-reared Ancistrus dolichopterus, causing death of these fish.