Potamon fluviatile as well as on the island of Sicily. Although it used to be found as far north as Lake Garda, "P. fluviatile" no longer occurs north of the River Po. In 1997 a population of "P. fluviatile" was discovered under the ruins of Trajan's Forum in the heart of Rome, living in canals built by the Etruscans which connect to the "Cloaca Maxima". Based on a genetic analysis, which demonstrated that these crabs were similar to those in Greece, researchers believe that they had been brought by the Greeks before the founding of the city, some 3000 years ago. The
Potamon fluviatile and across Central Asia as far east as northwestern India. The populations of "P. fluviatile" on the Peloponnese, Kefalonia, and Zakynthos may represent a separate, cryptic species, and the population from the Peloponnese was described in 2010 as "P. pelops". "P. fluviatile" was formerly divided into three subspecies: "P. f. algeriense", "P. f. berghetripsorum" and "P. f. fluviatile". The first two of these live in North Africa, and were later combined and separated from "P. fluviatile" as the species "Potamon algeriense". By 1983, the nominate subspecies (equivalent to the current circumscription of the species "P. fluviatile") had been divided into