''Stygobromus kenki'' is a rare 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 10,700 amphipod species cur ...

, a

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

. Its common names include Kenk's amphipod, Rock Creek groundwater amphipod, and Rock Creek stygobromid.Integrated Taxonomic Information System
/ref> This species lives only in

Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...

, the

Calvert Formation The Calvert Formation is a Formation (geology), geologic formation in Maryland, Virginia, and Delaware. It preserves fossils dating back to the early to middle Miocene, Miocene epoch of the Neogene Period (geology), period. It is one of the three ...

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

and

Montgomery County, Maryland Montgomery County is the most populous County (United States), county in the U.S. state of Maryland. As of the 2020 United States census, the county's population was 1,062,061, increasing by 9.3% from 2010. The county seat is Rockville, Maryland ...

, in the United States. It can be found only in the

Potomac River The Potomac River () is in the Mid-Atlantic (United States), Mid-Atlantic region of the United States and flows from the Potomac Highlands in West Virginia to Chesapeake Bay in Maryland. It is long,U.S. Geological Survey. National Hydrography D ...

watershed Watershed may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, an area of land where surface water converges (North American usage) Music * Watershed Music Festival, an annual country ...

.USFWS Species Assessment and Listing Priority Assignment Form
/ref> Its entire range is less than 40 square miles. It has only been found at five sites at springs or seeps in the local waterways.USFWS
Kenk's amphipod (''Stygobromus kenki'') Spotlight Species Action Plan.
/ref> This species is small, the largest female measuring about 5.5 mm in length and the largest male about 3.7 mm. It can only be identified by microscopic examination, which requires that the specimen be killed; therefore, scientists prefer not to attempt identification of these rare amphipods. The species lives in and near water in freshwater habitat. It can be found in detritus and sediment along springs and seeps. The amphipod was first collected in 1967 in

Rock Creek Park Rock Creek Park is a large urban park that bisects the Northwest, Washington, D.C., Northwest quadrant of Washington, D.C. Created by Act of Congress in 1890, the park comprises 1,754 acres (2.74 mi2, 7.10 km2), generally along Rock Cr ...

, where it was discovered by Roman Kenk. J. R. Holsinger then named it after him in 1978.Holsinger, J. R. (1978)
Systematics of the subterranean amphipod genus ''Stygobromus'' (Crangonyctidae), Part II: Species of the eastern United States.
Smithsonian Contributions to Zoology Number 266. This species can be found with another endangered amphipod of the same

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

, '' Stygobromus hayi''.

References

{{Taxonbar, from=Q7629358 kenki Fauna of the Eastern United States Freshwater crustaceans of North America Crustaceans described in 1978 Taxobox binomials not recognized by IUCN