Harpagoxenus sublaevis

25. Harpagoxenus sublaevis (Nylander, 1849)

Figs. 104, 105.

Myrmica sublaevis Nylander, 1849:33.

Worker. Pale yellowish brown to brown; head large, rectangular, with weakly concave occiput. Frontal carinae extend backward to enclose whole length of antennal scape. Antennae 11 segmented with intermediate segments strongly transverse and enlarged 4 segmented club. Eyes large, set midway at sides of head. Mesopropodeal furrow deep and distinct; propodeal spines broad and short. Femora and tibiae short and broadly rounded. Head and mesopropodeum longitudinally striate, petiole nodes and gaster smooth and shining. Whole body and appendages covered with long, acute, pale hairs. Length: 3.5-5.5 mm.

Queen. Ergatoid, similar to worker, but larger. Length: 4.7-5.7 mm. Normal alate queen has the head more square and the alitrunk relatively more massive, straightsided from above. Wings pale yellowish, short, forewings with open radial cell, 1 cubital cell and 1 discoidal cell. Length: 4.5-4.8 mm.

Male. Dark brown to black with paler legs and gaster. Head broader than long with rounded occiput. Mandibles edentate, short, reduced and nonfunctional. Eyes large, set anterior to midline of head, approximately 2/5 length of head. Ocelli present but inconspicuous. Antennal scape short, less than 2 following segments. Head and alitrunk finely sculptured but whole body moderately shining. Length: 3.7-4.5 mm.

Distribution. Denmark: only recorded from Jutland; throughout Fennoscandia, not uncommon. - Absent from British Isles. - Range: Pyrenees to Caucasus; North Italy to North Norway.

Biology. This species lives in obligate dulotic association with Leptothorax acervorum, L. muscorum and more rarely with L. tuberum. Workers may forage singly outside the nest and are capable of brood tending and can feed themselves but are evidently dependant on the host species for the continuation of the colony. In Denmark and Fennoscandia nests containing host species and inquiline are commonly found in twigs on the ground, tree stumps or under bark but in the mountains of Central Europe they occur more usually under stones. In mixed colonies the host queen may survive and alatae of both species may be developed within the same nest. Fertilised Harpagoxem: queens invade new nests of Leptothorax and appropriate mature larvae and pupae o. the host species to use both as food and for rearing as auxiliaries.