F. N. Morales-Serna, F. García-Vargas, R. M. Medina-Guerrero and E. J. Fajer-Ávila
The helminth communities of L. guttatus from Mazatlan Bay (MB) and Banderas Bay (BB), on the Pacific coast of Mexico, were studied during two consecutive years. A total of 536 fish were collected and 19 parasite taxa registered (six digeneans, two cestodes, nine nematodes, and two monogeneans). Infection levels of common helminth species (Helicometrina nimia, Siphodera vinaledwardsii, Tetraphyllidea gen. sp., Pseudoterranova sp., Ancyrocephalidae gen. sp. and Microcotyloides incisa) as well as the infracommunity indices varied significantly between MB and BB, and among dry and rainy seasons; however, no clear seasonal patterns were observed. Pseudoterranova larvae appeared frequently in MB, possibly because of the presence of the California sea lion in this locality. Similarity analysis did not show a clear separation of parasite species composition between both localities, which suggest that fish samples came from a single population of L. guttatus.
M. I. Grano-Maldonado, F. Rubalcava-Ramirez, A. Rodriguez-Santiago, F. Garcia-Vargas, A. Medina-Jasso and M. Nieves-Soto
The aim of this investigation was to identify the parasites present in the largely understudied pleasure oyster Crassostrea corteziensis in Sinaloa state in the northwestern Mexican Pacific coast. Inspection of twenty-eight oysters collected on “Ceuta” lagoon revealed the presence of the digenean Stephanostomum sp. (Digenea: Acanthocolpidae) cysts. Metacercariae were found encapsulated and embedded in the digestive gland and mantle tissue of oysters. The prevalence of infection revealed that 84.6 % were infected, the abundance was 13.62, with a mean intensity of 16.09 per host. The members of this genus are characterized by a double crown of spines in the cephalic region surrounding the buccal opening of the worm. Significantly, we report the first incidence of the digenean Stephanostomum sp of the family Acanthocolpidae parasitizing Crassostrea corteziensis. Further we report that this bivalve is now considered a new intermediate host, and the northwestern Mexican Pacific coast is a new geographical distribution area for this digenean. The findings contribute to our understanding of the biology, biodiversity and host preference of these parasites, with implications for health risks posed by human consumption of the pleasure oyster.