Faunistics and biogeography of terrestrial isopods (Crustacea, Oniscidea) from Liguria, north-western Italy.

The aim of this contribution is to illustrate the current state of knowledge of the Ligurian oniscidean fauna. Information from literature data and from material collected and examined in recent years are compared. Prior the start of our research in 2017, the total number of species recorded for Liguria was 73, belonging to 29 genera and 12 families. Most of these species were described or reported in a rather large number of papers on this topic published in the first half of the 20th century. From the ‘60s onwards, however, studies concerning terrestrial isopods from this region have considerably decreased, despite the large amount of undetermined material collected over the years and deposited in the scientific collections of several museums. The examination of both preserved and newly collected material has raised the number of species to 103, belonging to 38 genera and 17 families. Among these, it is worth to point out the presence of six species new to science, currently under description. Considering the limited territorial extension of Liguria (5,418 km2), 103 is a rather conspicuous number of species. For comparison, 78 species are recorded for Corsica (8,680 km2), 94 for Sardinia and surrounding islands (24,100 km2), 103 for Sicily and surrounding islands, including the Maltese Archipelago (26,148 km2), and 131 for Tuscany (22,943 km2). Moreover, as some areas or environments of the region have not been adequately investigated yet, such a sum is likely to increase. Such species richness, noticeable not only in terrestrial isopods, is probably due to the great environmental variability, the geographic position, and the geological context of Liguria, which is known to represent a significant biogeographic crossroad.