OCCURRENCE OF SCIADICLEITHRUM-MEXICANUM KRITSKY, VIDAL-MARTINEZ ET RODRIGUEZ-CANUL, 1994 (MONOGENEA, DACTYLOGYRIDAE) IN THE CICHLID CICHLASOMA-UROPHTHALMUS FROM A FLOODED QUARRY IN YUCATAN, MEXICO

Cichlids, Cichlasoma urophthalmus, collected in a flooded quarry in th e Yucatan peninsula Mexico, from January through June 1992, had high l evels of infection with the ancyrocephaline Sciadicleithrum mexicanum (Monogenea: dactylogyridae) in all monthly samples. Neither occurrence nor maturation of the worms exhibited any pronounced monthly fluctuat ion. The infection rate was found to be sizedependent, greater in long er fish. The worms occurred on primary lamellae of gill filaments of a ll arches, with lower numbers of parasites attached to the fourth gill arch. Otherwise, there was no significant site preference of worms. O nly minor histopathological changes were found at the sites of attachm ent, and these were restricted to the epithelial cells of the primary lamellae of the gill filaments. The lack of seasonal periodicity in th is tropical monogenean is compared to seasonal cycles typical of tempe rate species.