Dataset assembly
The assembled dataset is a synthesis of the last 40 years of research in the subterranean terrestrial fauna of the Canary Islands (Oromí et al. 2021), consisting of arthropods. The sample effort during this time was comparable across islands. The lack of records in Lanzarote (including La Graciosa) corresponds to a real absence of such subterranean fauna. The database includes all published and unpublished records of subterranean species from both cave and MSS habitats. We collected functional traits from the original description or relevant references and, if needed, completed from newly measured specimens. A complete list of the occurrences, as well as the definition of each trait, the methodology followed for its measurements, their values and the employed sources the sources can be found in [Dryad repository].