Freshwater snails (Mollusca: Gastropoda) from the Commonwealth of Dominica with a discussion of their roles in the transmission of parasites

We collected six species of freshwater snails from Dominica, including Biomphalaria kuhniana (Clessin, 1883), Gundlachia radiata (Guilding, 1828), Helisoma (=Planorbella) trivolvis (Say, 1817), Melanoides tuberculata (Muller, 1774), Neritina punctulata Lamarck, 1816, and Physa marmorata Guilding, 1828. Our collections indicate that un-reported species such as G. radiata and H. trivolvis are established on Dominica, West Indies. We tested a limited number of M. tuberculata for rickettsial pathogens, Neorickettsia spp., but did not identify this agent. Three species of snails previously reported from Dominica, Biomphalaria glabrata (Say, 1818), Biomphalaria straminea (Dunker, 1848), and Thiara granifera (Lamarck, 1822), were not collected. Our data suggest that B. glabrata has not re-emerged as a prominent component of the freshwater snail fauna since it disappeared or was locally eradicated. In addition, previous reports of B. straminea were probably misidentifications of B. kuhniana, and some abnormally large specimens of M. tuberculata from Freshwater Lake could be misidentified as T. granifera. Our sampling was not adequate to demonstrate that T. granifera was absent from Dominica. We determined that B. kuhniana was not eradicated by previous molluscan control regimes. Additional studies on the relationships of freshwater snails in Dominica to helminths of animals and humans are needed to understand the public and veterinary health significance of these snails.