Formica lugubris Zetterstedt

Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., Fauna Entomologica Scandinavica 8, pp. 1-174 : 148-152

61. Formica lugubris Zetterstedt , 1840. Figs. 173,249-255.

Formica lugubris Zetterstedt , 1840:449.

Worker. Bicoloured with distinct but not well demarcated dark patch on promesonotum. Frontal groove distinctly shining. Large punctures coarse and deep, widely dispersed among close set microscopic puncturation. Occiput with a thick fringe of hairs extending forward over area between ocelli and sides of head and laterally round to the eyes. Eye hairs erect and prominent. Body pilosity including gula, tibiae and femora more or less densely pilose. Some populations have scape hairs. Head width of largest workers 2.1 mm. Length: 4.5-9.0 mm.

Queen. Hairs and sculpture as in worker. Scale, basal face of gaster always with more or less numerous long hairs bent at the tip. Gaster, scutellum and frontal groove shining. Length: 9.5-10.5 mm.

Male. Black, legs and external genitalia yellowish to testaceous brovn. Hairs on eyes, genae below the eyes and dorsum of gaster prominent and clearly visible. Coarse punctures of head, alitrunk and gaster widely spaced among close set micropunctures. Gaster and scutellum always at least moderately shining. Length: 9.5-10.5 mm.

Distribution. Absent from Denmark and South Sweden; abundant throughout Norway and Finland and from Central Sweden northward. - Locally common in North Britain, local in South Ireland. - Range: northern Eurosiberia and European mountains from Pyrenees to Kamchatka and Japan, Italy to North Norway.

Biology. This is a robust active species. Colonies are often in groups with inter-connecting nests. It has similar habits to F. rufa but is able to forage at much lower temperatures and replaces F. rufa entirely from Central Fennoscandia to the far north. This species varies in the presence, abundance or absence of scape hairs in the female castes and some local populations in South Finland and in the Alps with such hairs have widely spaced micropunctures on the dorsum of the gaster as in F. rufa . Because of great variability among local populations in these areas it has not been possible to demarcate the extreme forms as a separate species but samples mainly from coastal areas and offshore islands in Nylandia include some extremely hairy specimens with queens consistently having wide spaced micropunctures which are well outside the range of F. lugubris as described by Yarrow (1955) and Betrem (1960). Bondroit (1917) briefly described a form, F. rufa var. nylanderi , as having long outstanding body and antennal hairs and F. nylanderi could be a suitable name for this form, if distinguished as a species.

F. lugubris spreads by colony fission but also by the adoption of fertile queens by Formica lemani . Such mixed incipient nests often under stones have frequently been seen in Norway and North Sweden (Collingwood, 1959).