Formica nigricans Emery

Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., Fauna Entomologica Scandinavica 8, pp. 1-174 : 153-154

63. Formica nigricans Emery , 1909 Figs. 263-266.

Formica rufa pratensis var. nigricans Emery , 1909: 187. Formica cordieri Bondroit , 1918: 126. Formica nigricans Emery ; Betrem, 1965.

Worker. Similar to F. pratensis in all respects except that body and appendage hairs tend to be more abundant and longer and most samples have 2 or 3 subdecumbent hairs protruding from the upper surface of the scape. Length: 4.5-9.5 mm.

Queen. Similar to F. pratensis in colour but with long bent hairs arising from. propodeum scale and basal face of gaster in addition to other parts of body which is often extremely hairy. Scapes often, and tibiae normally, with long suberect hairs. Length: 10.0-11.0 mm.

Male. Pubescence and appearance as F. pratensis but appendage hairs thicker and longer, with occasional erect hairs on hind tibiae longer than half width of tibiae. Pubescence on scape merging into subdecumbent protruding short hairs. Length: 9.5-10.5 mm.

Distribution. Very local. Denmark: SJ, El, WJ. - Sweden: from south to Vrm. - Norway: HO. - Range: Central Italy to Central Sweden, Portugal to Central Asia.

Biology. This species occurs in isolated nests and sometimes in a loose group of nests. In appearance and behaviour it is similar to F. pratensis but has been found nesting in dry sheltered banks, open lowland woodland and among scrub in partial shade in Mediterranean areas.

Note. Dlussky (1967) doubted whether F. nigricans could be specifically distinct and Paraschivescu (1972) gave evidence to suggest that the two forms intergraded in pilosity characters. The strongest argument for their separate identity lies in their geographical range. F. nigricans occurs much further to the south in Italy than F. pratensis , is characteristic of the Mediterranean area where F. pratensis has not been recorded. Conversely all samples from England, Finland, Channel Islands and most of the Netherlands are F. pratensis with no overlap in morphology. One aberrant polygynous polycalic colony is known from the southwest Netherlands with queens of mainly F. nigricans type but with variable pilosity.