An expanded ecological trait dataset and checklist for subterranean spiders of Macaronesia and continental Europe

Caves and other subterranean ecosystems impose highly selective environmental filters, driving the evolution of convergent and specialized traits in subterranean organisms. Here, we present the first comprehensive checklist and trait database for subterranean spiders of Macaronesia, thereby filling a significant knowledge gap relative to continental Europe. We compiled data through direct morphological measurements and literature review, covering 64 morphological and ecological traits for 61 species (14 families) from Macaronesia, along with 66 additional species in continental Europe not included in the previous checklist. After accounting for taxonomic changes, the checklist of European subterranean spiders now lists 637 species, of which 278 are considered obligate subterranean dwellers (troglobionts). We used multidimensional hypervolumes to compare the functional spaces of Europe and Macaronesia and explore some putative eco-evolutionary patterns shaping both assemblies. The expanded trait database is a valuable resource for ecological and conservation research, highlighting the need for continued exploration and protection of subterranean biodiversity, including on oceanic islands.