Hidden Endemicity of Lepidochitona Molluscs in the Black Sea: First Molecular Insights and Ecological Characterization Shows Genetic Isolation of Species in Littoral Habitats and Need for Conservation Efforts

We report two new for science genetically distinct Molecular Operational Taxonomic Units (MOTUs) of Lepidochitona molluscs from the Ukrainian and Romanian North-Western part of the Black Sea, assess their conservation status using IUCN ratings and evaluated their habitats according to the European Red List of Habitats. The genetic analysis was done based on DNA-barcoding analysis of the cox1 gene region. This is the first molecular data for this genus from the Black Sea region. Although previous morphological studies suggested the presence of two species in this area: mediterranean Lepidochitona cinerea and the recently described local species L. bondarevi, genetically they remained unstudied. Our DNA-barcoding analysis confirmed the presence of two species; moreover, analysis showed that the Ukrainian MOTU of Lepidochitona aff. cinerea is genetically different from those two European L. cinerea. Considering the uniqueness of Lepidochitona genus in the Black Sea basin, we assessed IUCN conservation status of species. Chitons L. bondarevi was classified as Vulnerable under IUCN criteria B2a,c(ii,iii) due to their Area Of Occurrence (AOO) criteria and fragmented locations which exacerbated by the ongoing from 2022 military conflict in the Black Sea. Chitons Lepidochitona aff. cinerea, the Black Sea MOTU, is more adaptable than L. bondarevi and is not limited to a narrow strip of coastal habitats, thus have not a high level of protection according to any of the IUCN criteria measured as they do not require it since they are less limited in terms of their habitat requirements. Our study underscores the endemicity of chitons in the Black Sea and needs in conservation efforts of Lepidochitona.