A hot-spot of native terrestrial isopods in an urban area in the Carpathians, Herculane Spa: an emergence of the past into the present (Crustacea, Isopoda)

Understanding urban biodiversity is an important task in the context of nowa-days rapid urban development. Urban expansion affects even areas with high biodiversity; the native fauna related to natural habitats is more sensitive to urbanization. We intended to observe the effect of an old town upon a group of soil-dwelling invertebrates, namely terrestrial isopods, in an area with a unique biodiversity, Herculane Spa, located in southwestern Romania. We identified 23 terrestrial isopod species in this small resort town with geothermal waters. This number is larger than in many regions of Romania, including other urban areas. More than a quarter of the species are endemic to the region or to the Carpathians in general. This fact confirms the biogeographical peculiarity of the Mehedinti Mountains. The old part of the town, built for touristic purposes, has a richer isopod fauna with native and endemic species. Forest and wetland species were also found in this area and in the periurban area. The newly built residential areas have fewer species, generally eurytopic. The presence of the local endemic species Trachelipus trilobatus is limited to natural regions and their vicinity, which proves its native origin. The town, with its special history, and its surrounding natural areas, shelters the native fauna of the region, despite the recent aggressive urban development. The resort areas are more important for the native fauna than the residential ones.