Common name: a freshwater crab
Identification: Geothelpusa dahaani is actually a species complex comprised of 2-3 species.
Native Range: Japan.
Hydrologic Unit Codes (HUCs) Explained
Puerto Rico &
Interactive maps: Point Distribution Maps
Several small crabs (about 1 inch across the carapace) were found at a Hyatt Hotel along the shore of Lake Las Vegas, a freshwater, artificial lake in the Las Vegas area, on two separate occasions in 2000. The first sighting, around March, included about a dozen crabs. All those collected at that time were females. The second sighting, around June, was of 2 males and 2 females. No females with eggs were found.
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Geothelphusa dehaani are found here.
Table last updated 2/27/2024
† Populations may not be currently present.
Means of Introduction: Although it was intially speculated that their introduction was likely the result of an aquarium release, their release has been traced to a sushi bar (A. Cook, pers. comm.).
Status: No more crabs have been collected since the initial find.
Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.
Revision Date: 6/29/2023
Fuller, P., 2024, Geothelphusa dehaani: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=193, Revision Date: 6/29/2023, Access Date: 2/27/2024
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.