A relict subterranean spider (Araneae: Linyphiidae: Troglohyphantes) reveals a unique component of the biogeography of Corsica

Abstract

Spiders of the genus Troglohyphantes (Araneae: Linyphiidae) exemplify one of the largest subterranean adaptive radiation across European mountain ranges, counting over 130 species and representing about one fifth of total species richness of cave spiders in Europe. Despite the emerging potential of Troglohyphantes as a biogeographical model, no attempt has been made to reconstruct the geological events underlying the current distribution patterns of the genus. By coupling traditional taxonomy with target gene sequence data and comparative functional trait analyses, we describe a new species of Troglohyphantes, the first reported from the island of Corsica (France). The species is characterized by a high level of subterranean adaptation and distinct morphological affinities with geographically distant congenerics. By means of time-stamped phylogenies, we tested contrasting hypotheses about the origin of the new species. The most parsimonious explanation suggests that the species diverged from an ancestral group of species originating in the Adriatic plate in the lower Miocene (~19 Ma), colonizing Corsica from the east. In the absence of relevant fossil records, the well-known geochronology of Corsica and the Western Mediterranean basin can be used in future studies to reconstruct the biogeography of the whole genus and for inferring the timeline of its diversification.