Disentangling species of the genus Limacia O.F. Müller, 1781, from southern Africa and Europe using integrative taxonomical methods, with the description of four new species

Uncertainty surrounding the number and identity of species of genus Limacia O.F. Muller, 1781, in southern African and European coastal waters presents an ongoing conundrum. Limacia clavigera (O.F. Muller, 1776) was previously thought to be the only species of its genus in the eastern Atlantic, with a distribution covering north- to south-eastern Atlantic waters. In the light of more recent molecular and morphological research, several distinct lineages have been uncovered in both Europe and southern Africa. Here, we gathered this information and included additional specimens from the two regions to produce an integrative morphological and molecular framework in which to delineate species. Molecular data of mitochondrial genes cytochrome oxidase subunit I and the large ribosomal subunit (16S rRNA) were amplified to perform molecular phylogenetic- and species-delimitation analyses. Findings led to the discovery and description of one new species from Europe: Limacia inesae sp. nov., three new species from southern Africa: Limacia jellyi sp. nov., Limacia miali sp. nov., and Limacia langavi sp. nov., and the confirmation of the validity of Limacia lucida (Stimpson, 1855) from southern Africa. Species-specific distributional and ecological traits further support species distinctions and historical biogeographical processes behind the inferred evolutionary relationships are further explored.