Opisthius
Kirby, 1837
Species Guides
1Opisthius is a of ground beetles in the Carabidae, containing the single Opisthius richardsoni. The genus is classified within the Nebriinae and tribe Opisthiini. Its sole species is distributed across northern North America, from Alaska and Yukon south to California and New Mexico. The genus is notable for its strong superficial resemblance to tiger beetles (Cicindelinae), which has led to frequent misidentification by collectors.
Pronunciation
How to pronounce Opisthius: /ɒˈpɪsθiəs/
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Identification
Opisthius is frequently confused with tiger beetles ( such as Cicindela) and with other ground beetle genera such as Elaphrus due to similar body shape and coloration. Accurate identification requires examination of morphological characters distinguishing Nebriinae from Cicindelinae. The genus can be distinguished from Elaphrus by subtle differences in body proportions and structural features; one collector noted that specimens labeled as Elaphrus were in fact Opisthius richardsoni. Professional identification or reference to specialized keys is recommended.
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Habitat
Banks of rivers and large brooks. Associated with riparian environments and wetland margins.
Distribution
Canada: Alberta, British Columbia, Northwest Territories, Saskatchewan, Yukon. United States: Alaska, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, Wyoming.
Life Cycle
Larvae have been recorded digging burrows. No further details on developmental stages are documented.
Human Relevance
Primarily of interest to entomologists and collectors. The has no documented economic importance. Misidentification as tiger beetles or Elaphrus has been noted in collection contexts.
Similar Taxa
- ElaphrusStrong superficial resemblance in body shape and coloration; specimens of Opisthius richardsoni have been misidentified as Elaphrus by collectors.
- Cicindela (tiger beetles)Similar overall appearance leading to confusion; Opisthius is a true ground beetle (Carabidae: Nebriinae) rather than a tiger (Cicindelinae).
Misconceptions
The is sometimes mistaken for tiger beetles due to convergent . It has also been specifically noted as being confused with Elaphrus, with one documented case of specimens labeled as Elaphrus being reidentified as Opisthius richardsoni.
More Details
Taxonomic note
The is , with Opisthius richardsoni as its sole . The species epithet is sometimes misspelled 'richardsony' in some sources.