Stygobromus kenki - Holsinger, 1978
Rock Creek Groundwater Amphipod
Other English Common Names: Kenk's Amphipod
Taxonomic Status: Accepted
Related ITIS Name(s): Stygobromus kenki Holsinger, 1978 (TSN 621650)
Unique Identifier: ELEMENT_GLOBAL.2.116980
Element Code: ICMAL05100
Informal Taxonomy: Animals, Invertebrates - Crustaceans - Amphipods
 
Kingdom Phylum Class Order Family Genus
Animalia Crustacea Malacostraca Amphipoda Crangonyctidae Stygobromus
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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Concept Reference: Fitzpatrick, J.F., Jr. 1983. How to Know the Freshwater Crustacea. Wm. C. Brown Co. Publishers. Dubuque, Iowa. 277 pp.
Concept Reference Code: B83FIT01EHUS
Name Used in Concept Reference: Stygobromus kenki
Conservation Status
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NatureServe Status

Global Status: G2
Global Status Last Reviewed: 15Sep2010
Global Status Last Changed: 15Sep2010
Rounded Global Status: G2 - Imperiled
Reasons: It is only known from fragmented localities in the Rock Creek drainage in Washington, DC and Montgomery County, Maryland (six sites total but two are historical) with extent of occurrence <100 sq. km, but threats have been determined to be low and localized and population information is not known.
Nation: United States
National Status: N2 (15Sep2010)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States District of Columbia (S1), Maryland (S1)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent: <100 square km (less than about 40 square miles)
Range Extent Comments: It is only known from the Rock Creek drainage in Washington, DC and Montgomery County, Maryland (Feller, 2005 cited in USFWS, 2007).

Area of Occupancy: 26-500 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 1 - 20
Number of Occurrences Comments: It was historically reported from a well in northern Virginia (tentative identification- now believed to be false) and is known from seeps in the Rock Creek drainage in Washington, DC (four in Rock Creek Park including East Spring and Sherrill Drive Spring), and two in Montgomery County, Maryland (one in a county park and one on private land) (Feller, 2005 cited in USFWS, 2007). According to Holsinger (2009), however, the immature male specimen from the well in Fairfax County formerly assigned to Stygobromus kenki was re-examined and appears to belong to a different species.

Population Size: Unknown

Number of Occurrences with Good Viability/Integrity: Unknown

Overall Threat Impact: Low
Overall Threat Impact Comments: Feller (1997) described both sites in Rock Creek Park as highly threatened and believed the existence of S. kenki is equally as tenuous to S. hayi, a listed species that occurs within the park boundary. These threats included rebuilding the stormwater infrastructure of the city by the District of Columbia, unusually high flood levels from Rock Creek. According to USFWS (2007), listing is not warranted as these threats are localized at only two of the five known sites for the species, the planned stormwater infrastructure rebuilding only affects a section of the Rock Creek drainage well downstream of all Kenks amphipod sites, and the increased flooding of Rock Creek is not supported nor is its direct effect on the species.

Short-term Trend: Unknown
Short-term Trend Comments: Trend information is not known but a few sites are only known historically (USFWS, 2007).

Long-term Trend: Decline of <50% to Relatively Stable
Long-term Trend Comments: Trend information is not known but a few sites are only known historically (USFWS, 2007).

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (<100 square km (less than about 40 square miles)) It is only known from the Rock Creek drainage in Washington, DC and Montgomery County, Maryland (Feller, 2005 cited in USFWS, 2007).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single nation

U.S. & Canada State/Province Distribution
United States DC, MD

Range Map
No map available.

Ecology & Life History
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Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): SPRING/SPRING BROOK
Subterranean Habitat(s): Subaquatic
Special Habitat Factors: Subterranean obligate
Habitat Comments: They can be found in dead leaves or fine sediment submerged in the waters of their spring-seep outflows in subterranean small springs and spring like seeps; often with intermittent flow and periods of drying in late summer or early fall (Holsinger, 1978).
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 14Sep2010
NatureServe Conservation Status Factors Author: Cordeiro, J.
Element Ecology & Life History Edition Date: 14Sep2010
Element Ecology & Life History Author(s): Cordeiro, J.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
Help
  • Fitzpatrick, J.F., Jr. 1983. How to Know the Freshwater Crustacea. Wm. C. Brown Co. Publishers. Dubuque, Iowa. 277 pp.

  • Holsinger, J. R. 2009. Three new species of the subterranean amphipod genus Stygobromus (Crangonyctidae) from the District of Columbia, Maryland, and Virginia. Pages 261-276 in S. M. Roble and J. C. Mitchell (eds.). 2009. A Lifetime of Contributions to Myriapodology and the Natural History of Virginia: A Festschrift in Honor of Richard L. Hoffman's 80th Birthday. Virginia Museum of Natural History Special Publication No. 16, Martinsville, VA.

  • Holsinger, J.R. 1978. Systematics of the subterranean amphipod genus Stygobromus (Crangonyctidae). Part II: Species of the eastern United States. Smithsonian Contributions to Zoology, 266: 1-144.

  • McLaughlin, P.A., D.K. Camp, M.V. Angel, E.L. Bousfield, P. Brunel, R.C. Brusca, D. Cadien, A.C. Cohen, K. Conlan, L.G. Eldredge, D.L. Felder, J.W. Goy, T. Haney, B. Hann, R.W. Heard, E.A. Hendrycks, H.H. Hobbs III, J.R. Holsinger, B. Kensley, D.R. Laubitz, S.E. LeCroy, R. Lemaitre, R.F. Maddocks, J.W. Martin, P. Mikkelsen, E. Nelson, W.A. Newman, R.M. Overstreet, W.J. Poly, W.W. Price, J.W. Reid, A. Robertson, D.C. Rogers, A. Ross, M. Schotte, F. Schram, C. Shih, L. Watling, G.D.F. Wilson, and D.D. Turgeon. 2005. Common and scientific names of aquatic invertebrates from the United States and Canada: Crustaceans. American Fisheries Society Special Publication 31: 545 pp.

  • U.S. Fish and Wildlife Service (USFWS). 2007. Endangered and threatened wildlife and plants; 90-day finding on a petition to list Kenk's amphipod, Virginia well amphipod, and the copepod Acanthoyclops colubiensis as endangered. Federal Register 72(175):51766-51770.

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