Lymnaeidae

Lymnaeidae, common name the pond snails, is a taxonomic family of small to large air-breathing freshwater snails, aquatic pulmonate gastropod mollusks, that belong to the clade Hygrophila. Lymnaeidae is the only family within the superfamily Lymnaeoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Bouchet & Rocroi (2005) recognized four subfamilies within Lymnaeidae: Vinarski (2013) established a new subfamily Radicinae within Lymnaeidae, but be considered position neither of Lancinae nor of extinct genera. Correa et al. (2010) examined phylogenetic relationships among 50 taxa of this family using a supermatrix approach (concatenation of the 16S, internal transcribed spacers ITS1 and ITS2 genes) involving both maximum likelihood and Bayesian inference. Her phylogenetic analysis demonstrates the existence of three deep clades of Lymnaeidae representing the main geographic origin of species (America, Eurasia and the Indo-Pacific region). It demonstrates that the nomenclature of most genera in the Lymnaeidae does not reflect evolutionary relationships. A cladogram based on sequences of 16S, internal transcribed spacers ITS1 and ITS2 genes showing phylogenic relations of Lymnaeidae by Correa et al. (2010): The nomenclature of genera has been one of the most confusing issues in the Lymnaeidae systematics. Most genus names are not fixed and are based more on phenotypic resemblances than on sound evolutionary and phylogenetic considerations. For instance, a single genus in Lymnaeidae was recognized by Walter (1968), two by Hubendick (1951), and up to 34 genera by others. Results by Correa et al. (2010) indicate that genera in Lymnaeidae do not reflect phylogenetic relationships, to the notable exception of Radix (including Radix natalensis).