An open occurrence dataset for European subterranean spiders

Motivation: Spiders are common inhabitants of caves and other subterranean habitats, where they play key ecological roles as generalist predators and strongly influence local food webs. They have been instrumental as model organisms for testing various eco-evolutionary hypotheses. Furthermore, strictly subterranean species exhibiting narrow ranges and high endemism are particularly significant for conservation planning and vulnerability assessments. Although high-quality data are essential for research on and conservation of subterranean spiders, such information remains scarce, especially regarding distribution patterns. To help fill this gap, we screened the literature, unpublished records, and open datasets to compile georeferenced occurrences of subterranean spiders across caves and other subterranean habitats throughout Europe. To illustrate one potential application of the compiled dataset, we also present a prediction of subterranean spider richness patterns across Europe using stacked species distribution models. Main types of variables contained: The European Subterranean Spider Dataset (ESSD) comprises 31,498 records of 637 subterranean-dwelling spider species, covering a range of information including taxonomy, locality details (such as location name, country, geographic coordinates, type of subterranean habitat), and reference information for each record. All variables are coded using the Darwin Core Standard, ensuring interoperability with the Global Biodiversity Information Facility (GBIF) and other biodiversity databases. Spatial location and grain: The collected data are distributed across 42 countries within the European continent, with varying spatial uncertainty. Most coordinates of localities are taken at the cave entrance (uncertainty of ca. 10 m), or at the nearest hamlet when precise coordinates are not available (uncertainty of ca. 1 km). Time period and grain: The data represent information made available between 1881 and 2026. Major taxa and level of measurement: 637 species (including morphospecies under description) of subterranean spiders across 28 families. These species span a gradient of ecological dependence on subterranean habitats, ranging from species still able to exploit surface habitats to obligate subterranean dwellers. Software format: The dataset is available in .csv format in Figshare data repository (available at https://doi.org/10.6084/m9.figshare.30696173).