A molecular phylogeny of the Calopiidae (Caenogastropoda: Truncatelloidea), with a taxonomic reassessment of Calopia imitata Ponder, 1999

The Calopiidae Ponder, 1999 (Caenogastropoda: Truncatelloidea) are a family of aquatic microgastropods endemic to Australia. Of its four known species, three—Calopia minutissima, C. laseroni and C. imitata (all Ponder, 1999)—are broadly distributed, whereas C. burni Ponder, 1999 is restricted to southeastern Victoria. We used a concatenated dataset (1,261 positions), containing fragments of the mitochondrial genes COI and 16S, to generate the first molecular phylogeny of the family. Bayesian inference and maximum likelihood analyses of the combined dataset elucidate evolutionary relationships within the Calopiidae. Furthermore, C. imitata and C. burni were recovered as a strongly supported clade of negligible sequence divergence, so we view these two taxa as conspecific. Consequently, C. burni is synonymized herein with C. imitata, and a taxonomic reassessment of C. imitata is provided. A discriminant function analysis of shell dimensions suggests some morphological differences between populations of C. imitata, possibly expressing ecophenotypic variability.