Morphological and molecular analysis of cryptic native and invasive freshwater snails in Chile

Abstract

Species delimitation in minute freshwater snails is often difficult to perform using solely shell morphology. The problem intensifies when invasive species spread within the distribution range of morphologically similar native species. In Chile, the Truncatelloidean snails are represented by the native genera Heleobia and Potamolithu s plus the invasive mudsnail Potamopyrgus antipodarum , which can easily be confused. Using an integrative approach, we performed molecular phylogenetic analysis and studied reproductive and morphological features to identify superficially similar forms inhabiting the central area of the country. Truncatelloidean snails were identified in 40 of 51 localities sampled, 10 containing Potamopyrgus antipodarum , 23 Heleobia and 7 Potamolithus . Based on these results and previously published data, the known distribution of the mudsnail in Chile encompasses 6 hydrological basins, including 18 freshwater ecosystems. The finding of the mudsnails in several type localities of native species/subspecies of “ Heleobia ” that were not find in situ suggests species replacement or significant extinction of native fauna, a hypothesis supported by the restudy of type material that shows that endemic forms belong to the genus Potamolithu s. This study shows the usefulness of integrative taxonomy not only resolving complex taxa with cryptic morphology but also measuring the extent of an ongoing invasion.

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.…”

“…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).…”

“…The shell and operculum were photographed and measured using a Motic SMZ-168 Stereomicroscope equipped with a Moticam 2000 camera. For taxonomic identification, morphological and microstructural features were studied following Collado et al (2019a), including protoconch, operculum and radula, which were observed using scanning electron microscopy (SEM) (Hitachi SU3500). The reproductive strategy of snails was studied by microdissections.…”

“…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.…”

Effects of osmotic and thermal shock on the invasive aquatic mudsnail Potamopyrgus antipodarum: mortality and physiology under stressful conditions

“…The New Zealand mudsnail (Potamopyrgus antipodarum; Tateidae, Mollusca) is an aquatic freshwater species native to New Zealand that has been frequently introduced, becoming invasive, in Oceania, Asia, Europe, and North America (Ponder 1988;Kerans et al 2005). It has recently been found in Chile, establishing a foothold in South America, too (Collado 2014;Collado et al 2019). This species can be spread passively by other organisms (on the feet, pelts, or plumage of birds and mammals) and by human vectors such as in the mud adhered to boats or motor vehicles (Alonso and Castro-Díez 2008).…”