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

This article focuses on the discovery and biogeographic analysis of *Troglohyphantes cyrnaeus* sp. nov., a newly described subterranean spider species from Corsica, France, belonging to the genus *Troglohyphantes* (family Linyphiidae). Using an integrative approach combining traditional taxonomy, molecular phylogenetics based on five gene regions, and functional morphological trait analyses, the study finds that *T. cyrnaeus* exhibits strong troglomorphic adaptations and is phylogenetically closest to species from the Adriatic region, particularly *T. deelemanae* from the Caucasus and the croaticus group from Slovenia and Croatia. Divergence time estimates suggest the species originated around 15–20 million years ago, coinciding with the geological connection between Corsica and the Adriatic plate in the Early Miocene, supporting an Adriatic origin over alternative hypotheses involving Iberian, Alpine, Messinian, or Pleistocene colonization routes. This research provides the first detailed biogeographic reconstruction for a *Troglohyphantes* species on a Mediterranean continental island and highlights the role of paleogeological events in shaping subterranean biodiversity in the region.