Tanygnathinina Reitter 1909:
Atanygnathus bicolor (Casey 1915)

Figure 1.12.11 Atanygnathus bicolor (Casey), right elytron. 1.12.12 A. bicolor, habitus. 2.2.5 A. bicolor, forebody.

Atanygnathus bicolor can be easily recognized among the Staphylininae by the lack of a visible neck, elongate maxillary palpi (Fig. 2.2.5), and its unique habitus (Fig. 1.12.12). It is also unique for its 5-4-4 tarsal formula. In overall appearance, it loosely resembles some Tachyporinae but lacks an epipleural ridge on the lateral portion of the elytron (Fig. 1.12.11).

This species is distributed mainly in the south-central and southeastern United States, extending along the east coast to New Hampshire and westward to Michigan. It is newly recorded  from Canada (Ontario) from a single specimen collected in Algonquin Provincial Park, and from the state of Michigan, both considerable distances from the northernmost record previously known in New Hampshire (Smetana 1990) (Map 3).

CANADA: ON: Nipissing Distr., Algonquin Prov. Pk., Broadwing Lake, 45.5977 -78.5275, 22-VIII-2008, island with sphagnum bog, pitfall, B. Wells, 1 (DEBU).
UNITED STATES: MI: Berrien Co., Mud Lake Bog, 28-IV-1984, sphagnum, L. E. Watrous, 10 (FMNH).

Eastern Canada: ON
Adjacent U.S.: NH, MI

Based on the small number of specimens from ECAS, this species appears to have both a spring and late summer/fall peak in adult activity.

This species is strongly associated with very wet moss and debris in wetlands and lakes (Smetana 1971). Specimens have been sifted from grass, sphagnum and litter in bogs, 'swept from grass by a pond' (Smetana 1990), and collected in a pan trap placed in a sphagnum mat on a lake. The specimens from Ontario and Michigan likely represent true populations for an otherwise southeastern species, as they were collected in the typical specialized habitat and further collecting may reveal that A. bicolor occurs broadly across ECAS.