Molecular insights into the taxonomy of Hypanis (Bivalvia, Cardiidae, Lymnocardiinae) in the Black Sea lagoons

Abstract

In this study, we used data from morphology and three DNA markers to assess the taxonomic status of the putative bivalve species Hypanis colorata and Hypanis angusticostata in a Black Sea lagoon, the Razelm Lake in Romania. The morphological data (the shape of shell ribs and the multivariate analysis of morphometric variance of three variables constructed as the ratios between the main dimensions of the shell) conWrmed that the two analyzed species are distinct morphological entities. Three molecular markers, one from the nuclear genome (18S rRNA) and two from the mitochondrial genome (16S rRNA and COI), showed extremely reduced sequence divergence (0-0.1%) between the two putative species. Based on these results, we suggest that H. angusticostata and H. colorata are morphotypes of a single species.

Mollusc species from the Pontocaspian region – an expert opinion list

“…It has recently been shown that many nominal taxa of fresh- and brackish-water snails and mussels described on the basis of their shell characters (the Pontocaspian molluscs rarely were described on the base of anatomical studies) lack a genetic support (with few exceptions such as e.g., Popa et al 2012, Stepien et al 2013) and thus do not represent evolutionary meaningful units. On the other hand, cryptic speciation is known within many taxa of molluscs in long-lived lakes (Albrecht et al 2006), and the Pontocaspian biota may include some previously unrecognised species.…”

“…Often, such distinctions are made based on the geographical isolation alone or on a range of morphological characters whose variation seems to be overlapping in geographical subpopulations. In order to assess whether the geographical populations are indeed species, we need combined morphological, ecological, and molecular data, but only few studies produced this information to date (e.g., Popa et al 2012 for Black Sea Basin Monodacna ). For the Aral Sea, we expect difficulties to obtain fresh material of almost all species for molecular analyses due to the obliteration of most of the lake and its fauna in the 20 th century (Andreeva and Andreev 2003, Plotnikov et al 2016).…”

“…Further investigations to confirm the synonymy are required. Monodacnaangusticostata was synonymised by Popa et al (2012) based on molecular evidence, even though some morphological distinction was reported from M.colorata , which they attributed to differential habitat preference (sediment type).…”

“…For the Aral Sea, the faunas appear to have largely disappeared with the demise of the lake system since the 1950s (Andreeva and Andreev 2003). Abundances of several other species in the Caspian Sea and Black Sea Basin have severely declined (Bologa et al 1995, Zaitsev and Mamaev 1997, Barannik et al 2004, Popa et al 2012). …”

New cockles (Bivalvia: Cardiidae: Lymnocardiinae) from Late Pleistocene Lake Karapınar (Turkey): Discovery of a Pontocaspian refuge?

“…In several recent works Monodacna and Adacna are considered to be subgenera of Hypanis (e.g. Popa et al, 2011). In other works (e.g.…”