Allocrangonyx

Allocrangonyx is a genus of troglobitic amphipod crustaceans from the South Central United States.^[3] The two species are both listed as vulnerable on the IUCN Red List.^[4][5] The animals are blind and unpigmented. During the male's development, the outer ramus of the third uropod differentiates into secondary segments and grows to a length greater than the animal's body length.^[6]

Allocrangonyx pellucidus lives in springs adjacent to Turner Falls.

Allocrangonyx
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Amphipoda
Family:	Allocrangonyctidae Holsinger, 1989 [1]
Genus:	Allocrangonyx Schellenberg, 1936 [2]
Species
Allocrangonyx pellucidus (Mackin, 1935) Allocrangonyx hubrichti Holsinger, 1971

Allocrangonyx pellucidus (Oklahoma Cave Amphipod) in a cave spring in the Arbuckle mountains of Oklahoma.

Allocrangonyx pellucidus

A. pellucidus, the "Oklahoma cave amphipod",^[2] is known from caves and springs in the Arbuckle Mountains of Johnston, Murray and Pontotoc counties, Oklahoma.^[7] The largest males reach 21.75 mm (0.856 in) long, while females reach 18 mm (0.71 in).^[3]

Allocrangonyx hubrichti

A. hubrichti, the "Central Missouri cave amphipod"^[2] or "Hubricht's long-tailed amphipod",^[6] was thought for many years to be endemic to the state of Missouri, but specimens were discovered in 1996, 283 km (176 mi) away, in a water well near Romance, White County, Arkansas.^[8] While the well is drilled into Pennsylvanian age sandstone, all previous records have been from Ordovician limestones and dolomites.^[8]

References

1. "Allocrangonyctidae Holsinger, 1989". Integrated Taxonomic Information System.
2. "Allocrangonyx Schellenberg, 1936". Integrated Taxonomic Information System.
3. John R. Holsinger (1971). "A new species of the subterranean amphipod genus Allocrangonyx (Gammaridae), with a redescription of the genus and remarks on its zoogeography". International Journal of Speleology. 3 (3/4): 317–331. doi:10.5038/1827-806x.3.3.11. Archived from the original on 2011-07-22. Retrieved 2010-04-14.
4. Inland Water Crustacean Specialist Group (1996). "Allocrangonyx hubrichti". IUCN Red List of Threatened Species. 1996: e.T873A13087606. doi:10.2305/IUCN.UK.1996.RLTS.T873A13087606.en.
5. Inland Water Crustacean Specialist Group (1996). "Allocrangonyx pellucidus". IUCN Red List of Threatened Species. 1996: e.T874A13087705. doi:10.2305/IUCN.UK.1996.RLTS.T874A13087705.en.
6. Julian J. Lewis (October 2002). "Conservation assessment for Hubricht's long-tailed amphipod (Allocrangonyx hubrichti)" (PDF). USDA Forest Service.
7. G. O. Graening; John R. Holsinger; Danté B. Fenolio; Elizabeth A. Bergey; Caryn C. Vaughn (2006). "Annotated checklist of the amphipod crustaceans of Oklahoma, with emphasis on groundwater habitats" (PDF). Proceedings of the Oklahoma Academy of Science. 86: 65–74.
8. Henry W. Robison; John R. Holsinger (2000). "First record of the subterranean amphipod crustacean Allocrangonyx hubrichti (Allocrangonyctidae) in Arkansas" (PDF). Journal of the Arkansas Academy of Science. 54: 153.