A survey of the occurrence, distribution and incidence of infection of helminth parasites of marine and estuarine mollusca from Galveston, Texas

Abstract

The results of a 3-year study of the helminth parasite fauna of the marine Mollusca of the Galveston Bay, Texas area are presented, including data on morphology, behavior, ecology, systematics and life cycles of the parasites, and their effects upon their molluscan hosts. Three species of Turbellaria, 34 species of digenetic Trematoda, eight species of Cestoda and one species of Nematoda were found among the 12,131 individual molluscs examined. Most of the parasites are identifiable with previously-described species, but five species of larval digenetic trematodes appear to be significantly different from known forms and may represent new species. These include a tail-less fellodistomatid cercaria, a trichocercous fellodistomatid cercaria, a renicolid xiphidiocercaria, a cercariaeum which encysts in its own redia, and a setose cystophorous appendiculate cercaria of the family Hemiuridae. The three turbellarians appear to utilize no other host in their life cycle. Of the 34 trematode species, 18 resemble species whose adult forms are parasites of warm-blooded aquatic vertebrates and 16 appear to be related to species whose adult forms are parasites of marine fishes. The eight cestode larvae are all forms whose adult stages occur in the gut of elasmobranch fishes, and the single nematode larva probably utilizes marine teleost fishes as hosts for the adult stage.