Cave Size Doesn’t Matter but Persistence and Sampling Techniques Do—Rich Cave-Dwelling Fauna Revealed in the Epikarstic Velika Pasica Cave (Slovenia, Europe)

Velika Pasica cave is situated in central Slovenia (Europe); it is 105 m long and 12 m deep, at an elevation of 670 m, and only has a 2–7 m thick roof and four permanent trickles from the epikarst zone. The second troglobiotic beetle, Anophthalmus hirtus Sturm, 1853, was described in this cave, twenty years after the first species, Leptodirus hochenwartii Schmidt, 1832, was described from Postojnska Jama cave (Slovenia). In the following decades, nine more terrestrial species and subspecies were described from Velika Pasica cave, which belong to the Mollusca, Pseudoscorpiones, Collembola and Coleoptera groups. After 2000, intensive research of the pools and trickles revealed an abundance of aquatic fauna, resulting in the description of four new species of Copepoda and two not yet determined epibiotic protozoans. A complete list of the terrestrial and aquatic fauna in Velika Pasica cave has never been published. To fill this gap, data from the literature and from intensive field work are presented here. To date, 89 terrestrial and 36 aquatic taxa have been recorded from the cave and the adjacent temporary spring and reservoir. Twenty-nine aquatic (including two epibionts) and 18 terrestrial species are strict cave-dwelling organisms. Thus, Velika Pasica cave ranks among the top global subterranean hotspots for species richness.