This area is likewise characterized by a high number of ancient, specialized cave-dwelling, interstitial and phreatic species belonging to different taxonomic groups, such as cyclopid and harpacticoid copepods, asellid and sphaeromatid isopods, amphipods (mainly Niphargus), syncarids, decapods, water mites, triclad turbellarians, ostracods, gastropods and amphibians.
Most stygobiontes are northern elements that show close affinities with central-european taxa; other ones are endemic or of uncertain affinities; a few species, Niphargus orcinus and Hadzia fragilis among the amphipods, and some cyclopid and harpacticoid copepods, show mediterranean features or similarity with the East-Balkan (Slovenia, Croatia and Romania) stygofauna. The western part of the province is marked by a high percentage of southern (Apennines) elements.
This stygofaunistical area is well defined and easily distinguishable from the Apennine one, as well as from the others, mainly by its amphipod fauna, which contains a great number of species of the genus Niphargus, most of which endemic for this province and by other specialized taxa, such as Carinurella paradoxa, Bogidiella albertimagni, Hadzia fragilis stochi and Rhipidogammarus rhipidiophorus. Other remarable, exclusive stygobiontes of this province are: cyclopid and harpacticoid copepods (Acanthocyclops sambugarae, Diacyclops ruffoi, Diacyclops languidoides italianus, Speocyclops infernus, Metacyclops gasparoi, Metacyclops trisetosus, Parastenocaris ruffoi, Parastenocaris acherusia, Parastenocaris gertrudae, Elaphoidella ruffoi, Elaphoidella dubia, Elaphoidella bidens, and the doubtful Moraria michilettoae), ostracods (Sphaeromicola stammeri), asellid isopods (Proasellus cavaticus, Proasellus franciscoloi, Proasellus pavani, Proasellus deminutus, Proasellus slavus, Proasellus intermedius, Proasellus gardinii, Chthonasellus bodoni), sphaeromatid isopods, the syncarids Bathynella ruffoi, Bathynella lombardica and Antrobathynella stammeri, the interesting decapod Troglocaris anophtalmus, gastropods of the genus Bythiospeum (with the exception of B. fabrianensis) and the species Moitesseria simoniana, the triclad turbellarians Polycelis benazzii, Atrioplanaria morisii and the species of the genus Dendrocoelum, the specialized water mite Kawamuracarus vardaricolus, and the remarkable stygobiont amphibian Proteus anguinus. Recently Stoch (1997) divided the Alpine province into several distinct stygofaunal subprovinces, pointing out the complexity of the groundwater assemblages of this area and suggesting as well that the stygofauna of northern Italy seems to be one of the richest in the world!
From a geological point of view, the Alpine province, comprising the territory north to the river Po and the West Alps, is marked by a noteworthy extent of karstic areas, especially in the eastern part, by a great number of caves, superficial phreatic and interstitial networks, and large deeper underground aquatic systems.