Stygian Cave Isopod
Caecidotea stygia Packard, 1871

Taxonomy

Synonyms

Description

Diagnostic characters

Ecological class

Stygobiont

Realm

Aquatic

Troglomorphy

Troglomorphic

Distribution

Type locality

Mammoth Cave, Edmonson Co. KY

Range

Known from 65 counties across eight states across two karst regions.

Continent

North America

Country

United States

States and provinces

Illinois, Indiana, Kentucky, Missouri, Mississippi, Ohio, Tennessee, Virginia

Counties

Illinois

Hardin, Johnson, Monroe, Washington

Indiana

Clark, Crawford, Greene, Harrison, Jefferson, Jennings, Lawrence, Martin, Monroe, Orange, Owen, Washington

Kentucky

Adair, Barren, Boyle, Breckenridge, Breckinridge, Carter, Clark, Crittenden, Cumberland, Edmonson, Estill, Fayette, Grayson, Green, Greene, Hardin, Harrison, Hart, Jackson, Jefferson, Jessamine, Larue, Lee, Madison, Marion, McCreary, Meade, Menifee, Mercer, Nelson, Owen, Powell, Pulaski, Rockcastle, Russell, Scott, Simpson, Warren, Wayne, Woodford

Missouri

Jefferson, St. Louis

Mississippi

Humphreys

Ohio

Adams, Clark

Tennessee

Fentress, Overton, Pickett

Virginia

Giles

Karst regions

Interior Low Plateau, Ozarks

Genetics

Molecular resources

111 sequences, retrieved 23 August 2026. Counts change as sequences are deposited. Search GenBank.

Download all 111 sequence records (CSV) Accession, marker, molecule type, length, GenBank definition and a direct link.

Specimens

Type material

Syntype

CRU-6786 · Museum of Comparative Zoology, Harvard

Collections holding material

190 cataloged lots in 6 collections. Compiled from GBIF and not an exhaustive census: many collections are not yet digitised, and holdings are added continually. Search GBIF for specimen records.

Download all 190 specimen records (CSV) Institution, catalog number, type status and preparation. No coordinates.

Conservation and management

NatureServe

G5 Secure

Global rank last reviewed 21 August 2002.

Subnational ranks

Illinois

SNR Unranked

Indiana

S5 Secure

Kentucky

SNR Unranked

Missouri

S1 Critically Imperiled

Ohio

SNR Unranked

Tennessee

S3S4 Vulnerable to Apparently Secure

Ranks looked up 23 August 2026. Conservation status changes, and a rank here is as current as that date and no more.

State and federal status

Not listed under the U.S. Endangered Species Act.

Other resources

Catalogue of Life

P7RG

GBIF

2205853

ITIS

92776

iNaturalist

215672

NCBI Taxonomy

3059448

References

• Bailey, V. 1933. Cave Life of Kentucky. US Department of Agriculture, Bureau of Biological Survey, Washington, DC, USA. 256 pp.
• Banta, A.M. 1907. The fauna of Mayfield's Cave. Carnegie Institution of Washington Publication 67: 1–114. https://www.biodiversitylibrary.org/item/60987. details
• Barr, T.C., Jr. & Kuehne, R.A. 1971. Ecological studies in the Mammoth Cave system of Kentucky. II. The Ecosystem. Annales de Speleologie 26: 47–96. doi:10.5038/1827-806X.3.1.10
• Carpenter, J.H. 1970b. Geocentrophora cavernicola n. sp. (Turbellaria, Alloeocoela): first cave alloeocoel. Transactions of the American Microscopical Society 89: 124–133. doi:10.2307/3224623
• Cooper, J.E. 1975. Ecological and behavioral studies in Shelta Cave, Alabama, with emphasis on decapod crustaceans. University of Kentucky, Lexington, Kentucky, USA. 364 pp.
• Cooper, J.E. & Beiter, D.P. 1972. The southern cavefish, Typhlichthys subterraneus (Pisces: Amblyopsidae), in the Mississippian Plateau of Kentucky. Copeia 1972: 879–881.
• Cooper, J.E. & Cooper, M.R. 2011. Observations on the biology of the endangered stygobiotic shrimp Palaemonias alabamae, with notes on P. ganteri (Decapoda: Atyidae). Subterranean Biology 8: 9–20.
• Cope, E.D. & Packard, A.S. 1881. The fauna of the Nickajack Cave. American Naturalist 15: 877–882.
• Fleming, L.E. 1972. The evolution of the eastern North American isopods of the genus Asellus (Crustacea: Asellidae). Part I. International Journal of Speleology 4: 221–256. https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=1605&context=ijs. details
• Giovannoli, L. 1933. Invertebrate life of Mammoth and other neighboring caves. In: Bailey, V. (ed), Cave Life of Kentucky, pp. 600–623.
• Harker, D.F., Jr. & Barr, T.C., Jr. 1979. Caves and associated fauna of Eastern Kentucky, Volume 3. Kentucky Nature Preserves Commission, Frankfurt, Kentucky, USA. 130 pp.
• Harker, D.F., Jr. & Barr, T.C., Jr. 1980. Caves and associated fauna of the Western Kentucky coal field, Volume 2. Kentucky Nature Preserves Commission, Frankfurt, Kentucky, USA. 114 pp.
• Hay, W.P. 1902b. Observations on the crustacean fauna of the region about Mammoth Cave, Kentucky. Proceedings of the United States National Museum 25: 223–236. doi:10.5479/si.00963801.25-1285.223
• Holt, P.C. 1973. Branchiobdellids (Annelida: Clitellata) from some eastern North American caves, with descriptions of new species of the genus Cambarincola. International Journal of Speleology 5: 219–256.
• Lewis, J.J. 1988. The systematics, zoogeography and life history of the troglobitic isopods of the Interior Plateaus of the eastern United States. University of Louisville, Louisville, Kentucky, USA. 281 pp.
• Lewis, J.J. 2004. Interstate 66 karst faunal study. Environmental Impact Statement. 17 pp.
• Lewis, J.J. 2005a. A biological inventory of caves of the Cumberland Plateau. Tennessee Chapter Cave Program, The Nature Conservancy, Nashville, Tennessee, USA. 156 pp.
• Lewis, J.J. 2009a. On the identity of Caecidotea nickajackensis (Crustacea: Isopoda: Asellidae). Proceedings of the Biological Society of Washington 122: 215–224. doi:10.2988/08-47.1
• Lewis, J.J. & Bowman, T.E. 1981. The subterranean asellids (Caecidotea) of Illinois (Crustacea: Isopoda: Asellidae). Smithsonian Contributions to Zoology 335: 1–66. doi:10.5479/si.00810282.335
• Lewis, J.J. & Lewis, S.L. 2005. Inventory of the subterranean fauna of Tims Ford State Park, Franklin County, Tennessee. Tennesee Natural Heritage Program, Nashville, Tennessee, USA. 28 pp.
• Nicholas, G. 1960. Checklist of macroscopic troglobitic organisms of the United States. The American Midland Naturalist 64: 123–160. doi:10.2307/2422897
• Niemiller, M.L., Maxwell, E. & Higgs, J.P. 2024. A biological inventory of Sinking Spring Cave at Abraham Lincoln Birthplace National Historical Park, Larue County, Kentucky, USA. U.S. National Park Service, Hodgenville, Kentucky, USA. 21 pp.
• Niemiller, M.L. & Zigler, K.S. 2013. Patterns of cave biodiversity and endemism in the Appalachians and Interior Plateau of Tennessee, USA. PLOS One 8: e64177. doi:10.1371/journal.pone.0064177
• Packard, A.S. 1871. The Mammoth Cave and its inhabitants. On the crustaceans and insects. American Naturalist 5: 739–761. https://www.jstor.org/stable/2447590. details
• Park, O., Roberts, T.W. & Harris, S.J. 1941. Preliminary Analysis of Activity of the Cave Crayfish, Cambarus pellucidus. The American Naturalist 75: 154–171. doi:10.1086/280943
• Pearson, W.D. & Boston, C.H., Jr. 1995. Distribution and status of the northern cavefish, Amblyopsis spelaea. Indiana Department of Natural Resources, Division of Fish and Wildlife, Nongame and Endangered Wildlife Program,, Indianapolis, Indiana, USA. 99 pp.
• Peck, S.B. & Lewis, J.J. 1978. Zoogeography and evolution of the subterranean invertebrate faunas of Illinois and southeastern Missouri. National Speleological Society Bulletin 40: 39–63.
• Poulson, T.L. 1961. Cave adaptation in amblyopsid cavefishes. University of Michigan, Ann Arbor, Michigan, USA. 185 pp. doi:10.7302/9847
• Steeves, H.R. 1963. The troglobitic asellids of the United States: the stygius group. The American Midland Naturalist 69: 470–481. doi:10.2307/2422923
• Webb, D.W., Taylor, S.J. & Krejca, J.K. 1993. The biological resources of Illinois caves and other subterranean environments. Illinois Natural History Survey, Champaign, Illinois, USA. 143 pp.

How to cite this account

Data sources and funding are listed in the Acknowledgments.

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