This situation led, long since, italian and numerous foreign scientists to take great interest in the italian underground habitats and organisms.

The first discovery of aquatic subterranean animals in Italy, as well as in the World, is dated as far back as 1550 (!) when Trissino referred to small, white and eyeless shrimps found in subterranean waters of the cave "Covolo di Costozza" in Venetia (North Italy); these animals were much later identified as amphipods crustaceans by Schellenberg (1936) who described them as Niphargus costozzae(=Niphargus stygius).

More than two centuries later, Pollini (1816) discovered another amphipod from the same region, Cancer pulex (=Niphargus bajuvaricus grandii), and Costa (1851) described Gammarus longicaudatus (=Niphargus longicaudatus) from subterranean waters of Campania (South Italy).

In the following years, some important researches were carried out by Bottazzi, Stammer, Benedetti, Gerlach and Ruffo, who intensively investigated interstitial, hyporheic and cave waters in Venetia, Tuscany and Apulia, discovering as well numerous noteworthy stygobitic taxa among crustaceans (copepods, ostracods, thermosbaenaceans, mysids, amphipods, isopos, decapods), triclad turbellarians, water mites, nematods and gastropods.

However it was not until the years 1950 to 1975 that the stygofauna of Italy received special consideration, and the number of investigators of the aquatic underground systems of this country proliferated greatly. Through these years, in fact, many systematic and faunistical researches were organized, and valuable papers were published by several authors, such as: Ruttner-Kolisko (1956), who investigated interstitial waters of North Italy, discovering the curious primitive oligochaete (microanellid?) Rheomorpha neiswestnovae; Stella a. o. (1951, 1953, 1957) who explored cave waters of Tuscany, discovering the thermosbaenacean Tethysbaena argentarii; Cottarelli (1969-1975) executed intensive studies on the harpacticoid fauna from interstitial waters of the central Apennines, Sardinia, and Apulia; Ruffo and Vigna Taglianti (1961-1968) promoted important research on the hyporheic and phreatic systems of Venetia, Tuscany and Apulia, discovering the new amphipod genus Ilvanella and the remarkable Metaingolfiella mirabilis; Delamare Deboutteville (1960) recorded the first syncarid from Italy, viz. the bathynellid Antrobathynella stammeri; Argano a.o.(1968-1975) conducted extensive research on isopods; Del Papa (1973) and De Beauchamp (1955) recorded stygobitic turbellarians from caves in the Abruzzes and Liguria respectively; Kiefer (1963-1968) carried out systematic studies on the cyclopid and harpacticoid copepods from interstitial waters of North Italy.

During the same time, other scientists (Franciscolo, Sanfilippo, Conci, Patrizi, Lanza, Parenzan, Cerruti, Martinotti, Boscolo, Ruffo, Puddu & Pirodda, Capolongo) provided preliminary, general reviews of the stygofauna of Liguria, Piedmont, Venetia, Tuscany, Sardinia, Latium and Apulia, discovering numerous interesting stygobitic taxa from the above regions.

In later years, from 1975 onward, stygobiological research was successfully continued by some very active zoological departments or laboratories and museums (Rome, L'Aquila, Padua, Catania, Naples, Verona, Siena) which incorporated ground waters investigations in their programs.

At present, thanks to the vast amount of work by zoologists, especially in the last 20 years, the knowledge of the italian stygofauna is becoming quite clear in its main outlines.The recent available literature contains very many papers by numerous scientists, who greatly enlarge the knowledge of the grondwater fauna of Italy. Among these, important contributions are due to the following authors:

Argano & Pesce (1979) (Asellid Isopods, phreatic waters of central Italy)
Benazzi & Gorbault (1977) (Triclads, cave waters, central Italy)
Bodon & Argano (1982) (Asellid isopods, cave waters, north Italy)
Bodon (1980) and Giusti (1980-1982) (Gastropods, interstitial and cave waters, central Italy)
Caruso (1982) and Caruso & Costa (1978) (stygofauna of wells, volcanic and karstic caves, Sicily)
Cottarelli a.o. (1978-1994) (Harpacticoid copepods, interstitial waters, central and southern Italy)
Danielopol (1981) (Ostracods, central and sothern Italy)
Dumnicka (1981) (Oligochaetes, phreatic waters, central Italy)
Ferrarese & Sambugar (1976) and Braioni a. o. (1980) (hyporheic biocoenoses, north Italy)
Karaman G. (1994) (Amphipods, Italy)
Kiefer (1981) (Copepods, cave and interstitial waters, north and central Italy)
Pesce a.o. (1976-1995) (copepods and microparasellid isopods, phreatic and hyporheic waters, Italy)
Ruffo (1982) (Amphipods, ground waters, Italy)
Serban (1987) (Syncarids, interstitial waters, central Italy, Sardinia)

From the above survey it appears that many researches and papers have been produced on the stygofauna of Italy, and that extensive research is still in progress. Nevertheless, actually we dispose of complete information only for certain regions (Liguria, Venetia, Latium,Tuscany, Sardinia, Apulia); for other ones, such as the Abruzzes, Campania, Sicily, Molise, Calabry, Basilicata and Umbria, we still have no, or scattered and incomplete data. However, there is already a large amount of information about numerous and significant stygobitic groups (cyclopid and harpacticoid copepods, isopods, amphipods, syncarids, thermosbaenaceans, mysids, decapods, gastropods, etc.) to outline a provisional, faunistical picture, as well as a biogeographical subdivision of Italy from a stygofaunistical standpoint.