Cichlids, Cichlasoma urophthalmus, collected in a flooded
quarry in the Yucatan Peninsula, Mexico, from January through
June 1992, had high levels of infection with the
ancyrocephaline Sciadicleithrum mexicanum (Monogenea:
Dactylogyridae) in all monthly samples. Neither occurrence nor
maturation of the worms exhibited any pronounced monthly
fluctuation. The infection rate was found to be sizedependent,
greater in longer risk The worms occurred on primary lamellae
of gill filaments of all arches, with lower numbers of
parasites attached to the fourth gill arch. Otherwise, there
was no significant site preference of worms. Only nanor
histopathological changes were found at the sites of
attachment, and these were restricted to the epithelial cells
of the primry lamellae of the gill filaments. The lack of
seasonal periodicity in lhis tropical monogenean is compared
to seasonal cycles typical of temperate species.
