An expert-curated dataset on cave-dwelling spider communities in the Western Italian Alps –an open tool for eco-evolutionary research

Biodiversity data is essential for eco-evolutionary research. However, data is often scarce for difficult-to-study ecosystems, such as caves and other subterranean environments. Here, we present a taxonomically and geographically consistent database of subterranean spiders from the Italian Western Alps, a coherent biogeographical region with a long history of subterranean fauna diversification. The database (https://doi.org/10.6084/m9.figshare.28524383.v1) comprises 370 geo-referenced subterranean sites (caves, mines, and other artificial subterranean systems). For each site, we provide information on the composition of the spider community (with species richness ranging from 1 to 8 species per site), along with local geomorphological and site features. Collectively, these communities account for 31 unique species and 945 unique geo-referenced occurrence records, which are made available via the Global Biodiversity Information Facility (GBIF: https://www.gbif.org/dataset/72eef995-01bd-44f2-937a-23dbfe66283d). In addition to the database, we provide a phylogeny for all species based on the cytochrome c oxidase subunit I (COI) gene fragment. This, combined with the interoperability of the European subterranean spider trait database (doi: 10.6084/m9.figshare.16574255.v2), enables the estimation of taxonomic, functional, and genetic diversity within these subterranean communities. We illustrate the utility of this database by estimating and mapping taxonomic, functional, and genetic richness across the Western Italian Alps, providing a comprehensive multi-dimensional view of subterranean spider biodiversity. Although restricted in geographical scope, we envision this database as a promising open resource for eco-evolutionary research and hope the broader scientific community will widely use it. Indeed, the joint availability of distribution data, traits, and phylogenetic information allows quantifying ecologically relevant differences among species, identifying functionally unique taxa, and assessing patterns of adaptation and specialization in subterranean environments, among many other questions.