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Coleoptera of Great Smoky Mountains National Park Species Pages

Family Histeridae

            Tribe Acritini

 Acritus exiguus (Erichson)

Description and Taxonomy

Length 0.8-1.0 mm. The genus belongs to the tribe Acritini characterized by minute compact oval bodies, lack of a prosternal lobe, four-segmented hind tarsi and sclerotized basal areas of antennal clubs (Kovarik & Caterino 2000). Together with the tribe Bacaniini, they form an informal group called "Microhisteridae," distinguished by their tiny body sizes (extremely rarely approaching 2 mm maximum length) and compact short elliptic body shapes. Two genera of acritines, Acritus and Aeletes, are known in the GSMNP. Acritus may be distinguished by the lack of lateral striae on the clypeus and presence of small, but distinct scutellum. Acritus exiguus differs from the other congener in the park, A. acaroides, by it dorsoventrally flattened body shape and  the lack of rugose microsculpture on elytra and a distinct row of punctures along the base of the pronotum.

Life History

This species is found under the bark of dead trees, both conifers and deciduous. Detailed information on food habits is lacking, but it is suspected to be a predator of tiny arthropods, e.g. springtails, mites, insect eggs.


 Widespread in eastern N America, from southern Canada  to Texas and Florida (Bousquet & Laplante 2006). It is known in the GSMNP from a single locality at 545 m.

Conservation Concerns

Not under threat.

Locality records in GSMNP.


Development of these pages was supported by grants from Discover Life in America and the National Science Foundation (DEB-0516311).


Bousquet, Y. and S. Laplante. 2006.  Coleoptera Histeridae. The insects and arachnids of Canada. Part 24. NRC Research press, Ottawa. 485 pp.

Kovarik, P.W. and M. S. Caterino.  2000. Histeridae. Pp. 212-227 in: Arnett, R. H. and M. C. Thomas (eds.) American beetles. Vol. 1. CRC Press, Boca Raton  - London - New York - Washington.

 Posted 13 August 2007, A. K. Tishechkin, Louisiana State Arthropod Museum.

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