Systematic evaluation of cryptic freshwater snails from central Chile, including the enigmatic Littoridina santiagensis (Gastropoda, Truncatelloidea)

Abstract

In 1944, Walter Biese described Littoridina santiagensis (Cochliopidae) from Estero Dehesa based exclusively on external shell features and a second allopatric population in Yeso Spring three years later. Different samplings carried out since 2011 in the type locality have only provided specimens of the morphologically similar invasive mudsnail Potamopyrgus antipodarum (Tateidae) raising doubts about the identity of the species. The recent finding of two snail morphotypes in Yeso Spring, a thick shelled form congruent with type specimens of L. santiagensis and a slender one morphologically associable to P. antipodarum, allowed comparative studies, including the taxonomic analysis of additional populations with similar shell morphology occurring in central Chile. A DNA barcoding (COI) approach identified the slender form from Yeso Spring in Maipo Basin and a second population from the contiguous Rapel Basin indeed as the invasive P. antipodarum, however, L. santiagensis was recovered among species of Potamolithus (Tateidae) justifying the binomem Potamolithus santiagensis as a new combination. Besides recognition of other three populations as belonging to Potamolithus, the molecular analysis also suggests trans-Andean dispersal of this group of snails in the Southern Cone of South America.