Molecular evidence enables further resolution of the western North American Pyrgulopsis kolobensis complex (Caenogastropoda: Hydrobiidae)

Abstract

Mitochondrial COI sequence variation was examined in members of the Pyrgulopsis kolobensis complex to clarify further the confused taxonomy of these springsnails, which were treated as a single species prior to a recent study that recognized five morphologically and genetically distinct species for the populations in the Virgin River drainage of southern Utah. Phylogenetic analyses of 44 currently undescribed populations in this complex from the eastern Great Basin and Snake River basin congruently resolved five divergent lineages. One of the lineages contained most of the newly sequenced specimens as well as the haplotypes of three currently recognized regional species. The mean genetic distance within this lineage was slight (0.7%) and consequently we treat it as a single, morphologically variable species for which the name P. pilsbryana has precedence and should be used. Two of the other lineages (both having small geographic ranges) are sometimes sympatric both with each other and with P. pilsbryana (as envisaged herein), but could not be distinguished morphologically and may be divergent haplogroups of P. pilsbryana or undescribed cryptic species. The remaining two lineages are single populations in eastern Nevada and southern Utah that, together with other, previously detected lineages from these areas, will require additional morphological study to determine their taxonomic status. Further molecular sampling, especially of the many populations in Nevada that have not been analysed so far, is also needed to help complete the taxonomic revision of the P. kolobensis complex.