Genetic variation of the lymnaeid Radix rubiginosa (Michelin, 1831) (Mollusca, Gastropoda) and other freshwater snails in Thailand examined using mitochondrial COI sequences

ABSTRACT Freshwater lymnaeid snails, for example Radix rubiginosa, may serve a crucial role as the sole intermediate hosts of several trematodes of medical or veterinary importance causing diseases in livestock and humans including fascioliasis, schistosomiasis and echinostomiasis. In Thailand, there is little information on the genetic variation of lymnaeid snails. Thus, this study explores the mitochondrial cytochrome c oxidase subunit I (COI) sequence variation of lymnaeid and physid snails collected from different geographical areas in Thailand, with the main focus on R. rubiginosa. In all, 175 R. rubiginosa, 7 Orientogalba sp., 9 Racesina sp., and 61 Physella acuta were collected from 36 localities in Thailand. A high level of genetic variation was detected in R. rubiginosa, with 40 haplotypes being recorded. Phylogenetic analyses revealed two clades (possibly species) in the material identified as R. rubiginosa. One clade contained all samples examined in this study, together with a sequence from Indonesia, while the second clade comprised specimens found in Singapore, Malaysia, and Vietnam. Seven haplotypes of P. acuta were clustered into clade A, the globally invasive lineage of this species.