Formicoxenus nitidulus

24. Formicoxenus nitidulus (Nylander, 1846)

Figs. 102, 103.

Myrmica nitidula Nylander, 1946b: 1056.

Worker. Reddish yellow to brown: whole surface of body smooth and shining with scattered acute pale hairs. Antennal club 3 segmented as long as rest of funiculus; propodeal spines short, set horizontally. Length: 2.8-3.4 mm.

Queen. Very like the worker, somewhat darker; eyes larger and ocelli present. Forewings with 1 cubital cell and 1 discoidal cell with open radial cell. Length: 3.4-3.6 mm.

Male. Worker like but with additional antennal and gaster segments; ocelli present. Antennae with funiculus relatively longer, terminating in 4 segmented club. Length: 2.8-3.2 mm.

Distribution. Throughout Denmark and Fennoscandia; local in England and Scotland. - Range: Spain to Eastern Siberia, North Italy to latitude 70° N.

Biology. This ant occurs only in the nests of Formica rufa and allied mound building species. It is ignored by its host among which the inquiline species moves freely. Individual nests contain only a few individuals, up to about 100, but often several nests are present within one mound of the host. Nests are located in fragments of wood, hollow twigs, bases of old bracken stems and in the earth floor of the Formica mound. Intermediate forms between queen and worker are common and individuals normally remain concealed within the nests but may wander on the mound surface on warm dull days. It is not known to feed on the Formica brood but in captivity will destroy Leptothorax larvae. Males and winged females may be found during July and August, mating occurring on the surface of the Formica mound.