Formica gagatoides Ruzsky

44. Formica gagatoides Ruzsky, 1904

Figs. 164,180,181.

Formica fusca var. gagatoides Ruzsky, 1904: 377.

Formica gagatoides Ruzsky; Holgersen, 1943:10 (redescription).

Worker. Black, mandibles and appendages brown. Head and alitrunk dull, gaster shining with sparse adpressed pubescent hairs - length less than half interspace width. Propodeum angled in profile. Petiole scale broadly heart-scaped with more or less emarginate dorsal border. Erect hairs on gaster restricted to posterior border of tergites; mid femora normally without outstanding hairs. Length: 4.2-6.0 mm.

Queen. Colour and pubescence as worker. Scutellum and gaster conspicuously shining. Pronotal hairs sparse and restricted to anterior part; mid femora bare. Length: 7.0-8.0 mm.

Male. Black, legs and external genitalia yellowish. Head and alitrunk finely punctured with scutellum and propodeum as well as gaster distinctly shining. Scale broadest at apex, with shallow emargination and with scattered long hairs overreaching rounded side margins of dorsal crest. Length: 6.0-7.0 mm.

Distribution. North and Central Fennoscandia from North Cape south to Buskerud and Opland in Norway, Varmland and Medelpad in Sweden and Tavastia borealis in Finland. Abundant in northern areas and in mountains, more local in centre and absent south'of latitude 60° in Norway to latitude 62° in Finland. - Range: exclusively arctic from Norway to Northeast Siberia.

Biology. This is one of the few Fennoscandian species that does not occur in the Alps or other mountains of Central Europe. In behaviour and general appearance it resembles F. fusca, which it replaces in the north, but can be immediately distinguished by the shining gaster from F. fusca and from F. transkaucasica by the duller head and alitrunk. It lives in small colonies of a few hundred workers with one or a few queens. Alatae fly in July and August.