Temporal distribution and population structure of two congeneric species of Cucullanus (Nematoda: Cucullanidae) in Orthopristis ruber in Venezuela.

The qualitative and quantitative parameters of temporal distribution of Cucullanus tripapillatus and Cucullanus chrysophrydes in the intestine of Orthopristis ruber in the Caribbean Sea on the north of Margarita Island, Venezuela were analysed. A total of 540 fish were collected at random from the catch of commercial trawlers during 1982-83 and 1992-93. Both species of Cucullanus were found throughout the year; prevalence and mean intensity of C. tripapillatus were higher than that of C. chrysophrydes. A significant difference was found in infection between the two years of sampling. Female worms were more abundant than male in both years. Both species exhibited pronounced prevalence and maturity in September and March of each year, indicating seasonality. The patterns of occurrence of the two species of Cucullanus in O. ruber did not change in the 10-year interval but the host size and number of parasites declined, which may be due to over-exploitation of definitive fish hosts.