The Terrestrial Isopods (Crustacea, Isopoda, Oniscidea) of the Mediterranean Basin Biodiversity Hotspot: An Overview

The Mediterranean basin is one of the largest biodiversity hotspots in the world. It includes a vast set of terrestrial habitats and hosts an exceptionally diverse flora and fauna. Terrestrial isopods (Crustacea, Oniscidea), comprising over 4100 species described worldwide, constitute a diverse and significant component of soil biodiversity. The Oniscidea of the Mediterranean have received considerable attention from the second half of the 19th century onwards. However, the taxonomy and distribution of many taxa remain unclear, primarily due to limited knowledge and inadequacies in old species descriptions. This chapter aims to provide a general overview of the diversity of the Oniscidea within the Mediterranean hotspot, with a particular focus on the more distinctive taxa or those that best characterize this area. Overall, more than 1000 species of terrestrial isopods inhabit the Mediterranean region, with Italy, Greece, and the Iberian Peninsula being the major hotspots with a significant proportion of endemic species. The richness and complexity of the Oniscidean fauna in the Mediterranean basin is thus emphasized, while acknowledging the challenges of fully assessing the diversity of this group. Finally, some brief remarks regarding the conservation status of this taxon are given.