Leptothorax muscorum

Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., Fauna Entomologica Scandinavica 8, pp. 1-174 : 72-73

18. Leptothorax muscorum (Nylander, 1846) Figs. 93-95.

Myrmica muscorum Nylander , 1846b: 1054.

Worker. Pale brown to brown with antennal clubs and head often slightly darker. Propodeal spines short but distinct. General appearance more slender than L. acervorum . Head striate, alitrunk rugose and gaster smooth. Appendage hairs few and adpressed. Clypeus in some Scandinavian series have a distinct median concavity as described for L. gredleri Mayr (Buschinger, 1966) but they are not otherwise different from the typical species. Length: 2.4-3.2 mm. Queen. As worker, normally darker. Length: 2.7-3.2 mm.

Male. Brownish black; occasional semi-erect hairs on tibiae but much shorter and less profuse than in L. acervorum . Antennae 12 segmented with very short scape.

Distribution. South to Central Fennoscandia not uncommon, till about latitude 63°. Local in Denmark. Absent from British Isles. - Range: Appenines to Central Scandinavia and Pyrenees to Urals, not found in British Isles but common in continental Europe.

Biology. This species is similar to L. acervorum but smaller and more slender. In Scandinavia, it Ls restricted to sheltered valleys in woodland areas where it nests in stony banks, tree stumps or under bark. Its habits are similar to those of L. acervorum with small colonies having one or occasionally two queens. Males and alate queens are found in July and August.