The Sardinian province, nothwithstanding the limited and discontinuous extent of karstic areas, is remarkable due to the great diversity and old age (Palaeozoic and Mesozoic) of the karst which gave rise to a considerable number of different, sometimes well separated underground aquatic systems, viz. inland and coastal caves, deep and superficial phreatic networks, large hyporheic systems, underground rivers, etc.

From a biogeographical point of view, this province holds a typical western stygofauna, that shows close affinities with french groundwater fauna, sharing with this country some stygobitic taxa such as the copepods Acanthocyclops brachypus, Halicyclops troglodites, Metacyclops subdolus, Parapseudoleptomesochra minoricae, and the amphipod Salentinella angelieri; on the other hand, some species show close similarity with Sicilian and North-african taxa; other ones are southern elements or vicariant species, that are assumed to be recent immigrants in the ground waters of this province, and whose colonization is supposed to coincide with the quaternary connection between Sardinia and continental Italy (Tuscany).

The Sardinian province contains a great number of exclusive or rare species among different taxonomic groups: cyclopid (Diacyclops ichnusae, Diacyclops sardous, Diacyclops nuragicus, Speocyclops sardous) and harpacticoid (Nitocrella beatricis, Elaphoidella oglasae, Ichnusella eionae, Arenopontia nesaiae, Arenopontia subterranea, Delamarella galateae, and a considerable number of species of the genus Parastenocaris) copepods; ostracods (Mixtacandona chappuisi, Mixtacandona cottarellii); asellid (Proasellus patrizii), stenasellid (Stenasellus nuragicus, Stenasellus assorgiai, Stenasellus racovitzai) and microparasellid (Microcharon nuragicus, Microcharon silverii) isopods; amphipods (Niphargus longicaudatus, Niphargus stefanellii, Ingolfiella cottarellii, Ilvanella inexpectata, Bogidiella calicali, Bogidiella vandeli, Bogidiella silverii, Bogidiella ichnusae); syncarids (Sardobathynella cottarellii) and water mites (Acherontacarus cicolanii).