Abstract
Biogeographical regions are indispensable for addressing fundamental questions in biogeography, evolutionary biology, and conservation. However, achieving accurate bioregionalization analyses for subterranean fauna remains a formidable challenge due to the scarcity of biological data. In this study, we combined GIS data on karst potential, geology, and tectonics, to delineate twelve geokarstic sectors across the Ibero-Balearic territory, which we anticipate will elucidate patterns in terrestrial subterranean biodiversity. We discuss the diversity patterns of cave-dwelling Diplura species in the context of these twelve natural units. Our findings revealed that only the area variable was significantly linked to variations in species richness when various ecogeographical variables were used to characterize each geokarstic sector. The resulting map (IBERGEOKARST v.1) serves as a foundational, albeit preliminary, tool designed to stimulate further research and guidance to develop a robust and formal bioregionalization of subterranean biota in the Ibero-Balearic region. By offering a structured framework, this work aspires to advance our understanding of the hidden diversity within subterranean ecosystems, thus paving the way for more precise conservation strategies.