Atrecus is distinguished from other Staphylininae by the following combination of characters: a pair of plates anterior to the prosternum (Fig. 2.1.2), thick neck (Fig. 2.4.1), antennal bases closer to each other than to the nearest eye (Fig. 2.4.1), mandibles projecting forward (Fig. 2.4.1), and elytra not overlapping (Fig. 10.2.1).

Two species occur in ECAS (A. americanus (Casey) and A. macrocephalus (Nordmann)) mainly under the bark of coniferous trees (Fig. 10.2.2). They can sometimes be collected in debris around the bases of old trees (Smetana 1982). Atrecus is transcontinental in Canada and occurs in eastern and western United States. This genus was revised by Smetana (1982) and will be reviewed in a future publication on Othiini and Xantholinini.