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

Abstract

Walter Biese described Littoridina santiagensis Biese, 1944 (Cochliopidae) from Estero Dehesa in 1944 based exclusively on external shell features and a second allopatric population in Yeso Spring three years later. Since 2011 different samplings have been carried out at the type locality and have only provided specimens of the morphologically similar invasive mudsnail Potamopyrgus antipodarum Gray, 1843 (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 Pilsbry, 1896 (Tateidae), justifying the Potamolithus santiagensis (Biese, 1944) comb. nov. Besides recognition of three other 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.

Range extension of the invasive Potamopyrgus antipodarum (Gray, 1843) (Gastropoda, Tateidae) in Chile, and a summary of its distribution in the country

“…Two identical partial COI sequences of 639 bp from PaMR1-LMSM-UBB and PaMR2-LMSM-UBB were obtained. The BLASTn analysis comparing this haplotype against GenBank database found 100% identity with sequences of P. antipodarum previously published (Ponder et al 2008;Neiman et al 2010;Hamada et al 2013;Collado et al 2014Collado et al , 2019aCollado et al , 2019b, confirming the taxonomic assignment based on morphology.…”

“…Although the distribution of the NZMS in Chile is not continuous regarding its absence in some contiguous basins, the species is present in five political regions of the country, specifically from the Coquimbo to Maule regions. With the new record provided here, the occurrence of the NZMS in Chile reaches 19 localities (Collado 2014(Collado , 2016Collado et al 2019aCollado et al , 2019b; present study) (Fig. 2, Table 1).…”

“…Identification. NZMS are similar in shell morphology to species of the genus Heleobia and Potamolithus (Collado et al 2019a(Collado et al , 2019b, which include several native species in Chile. Species-specific identification was performed after observation of the protoconch and radula, which differ among genera (Collado et al 2019a).…”

“…This finding represents the first record of the species in the Maule River, expands its southern distribution to this locality and, in turn, constitutes the southernmost record of the species known until now in South America. The previous southernmost record was Lo Carreño in Rapel river basin, O'Higgins Region (Collado et al 2019a(Collado et al , 2019b.…”

“…However, NZMS was present earlier in Chile but it was overlooked by and , who ascribed part of their samples to the genus Heleobia Stimpson, 1865. Subsequently, NZMS has been reported from additional localities in Chile, with the southernmost record from Lo Carreño irrigation canal in the Rapel river basin (Collado 2016;Collado et al 2019aCollado et al , 2019b.…”