''Stygobromus lucifugus'', the rubious cave amphipod is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species of

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

in the family

Crangonyctidae Crangonyctidae is a family of cave-dwelling freshwater amphipod crustaceans. It contains the following genera: *'' Amurocrangonyx'' Sidorov & Holsinger, 2007 *'' Bactrurus'' Hay, 1902 *''Crangonyx ''Crangonyx'' is a genus of crusta ...

. It was first described by Oliver Perry Hay who found it living in a well near Abingdon,

Knox County, Illinois Knox County is a county in the U.S. state of Illinois. According to the 2020 census, it had a population of 49,967. Its county seat is Galesburg. Knox County comprises the Galesburg, IL Micropolitan Statistical Area. History Knox County was ...

, United States, and it was

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to that state.

References

lucifugus Freshwater crustaceans of North America Extinct animals of the United States Extinct invertebrates since 1500 Extinct crustaceans Crustaceans described in 1882 Taxa named by Oliver Perry Hay Taxonomy articles created by Polbot Endemic fauna of Illinois Cave crustaceans Endemic crustaceans of the United States {{Amphipod-stub