Leptothorax nylanderi

Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., Fauna Entomologica Scandinavica 8, pp. 1-174 : 74

19. Leptothorax nylanderi (Forster, 1850) Fig. 96.

Myrmica nylanderi Foerster , 1850:53.

Worker. Yellow to pale yellowish brown, the head sometimes darker, broadly infuscate on the first gaster segment. Antennae including clubs and legs concolorous with the rest of the body. Head longitudinally striate, alitrunk finely rugose, gaster smooth. Legs without erect hairs. Antennae twelve segmented; mesopropodeal impression distinct and clearly visible in side view. Length: 2.3-3.4 mm.

Queen. As worker, but with enlarged alitrunk and banded gaster. Length: 4.2-4.7 mm.

Male. Brownish black with pale yellowish appendages, mesonotum between the notauli, and most of the rest of the alitrunk, smooth and shining with some striae at the sides of the promesonotum. Antennae 13 segmented; funiculus segments 2-5 nearly twice as long as broad. Length: 3.0-3.2 mm.

Distribution. Sweden: Gotska Sandon and Gotland, and on the mainland from a few of the southern districts. - Not found in the other Scandinavian countries. - Not uncommon in parks and woodland in South England. - Range: Central and South Europe from Spain to Caucasus, north to South Sweden.

Biology. This species is immediately distinguishable from all other North European Leptothorax with twelve segmented antennae in the worker caste by the distinct mesopropodeal suture seen as a clear depression in the dorsal profile. It is normally a woodland bark inhabiting species but occasionally is found under stones. Its morphology and biology in France where it is common, has been intensively studied by Plateaux (1970). The species is normally monogynous with between 100 and 200 workers. Is is somewhat more aggressive than L. acervorum and despite its small size will attack and sting freely. Alate queens and males are developed during July and flights occur during early August.