27. Strongylognathus testaceus (Schenck, 1852) Figs. 108,109. Eciton testaceum Schenck, 1852:117. Worker. Yellowish brown. Head rectangular with pronounced occipital emargination and posterolateral angles. Body shining with long fine pale hairs present also on appendages. Sculpture variable, with longitudinal striae present or more or less effaced on head and alitrunk. Length: 2.0-3.6 mm. Queen. Darker than worker, brownish with paler appendages. Wings pale with 1 cubital cell, 1 discoidal and an open radial cell. Length: 3.5-3.8 mm. Male. Dark brown with pale brown appendages. Head small narrower than promesonotum. Occiput emarginate sharply angled postero-laterally. Antennal scape shorter than second funiculus segment. Length: 3.2-4 mm. Distribution. Very rare in S. Sweden, only recorded from Sm. and 01. - Recorded in England from Devon, Dorset and Hants very locally. - Range: Pyrenees to Ukraine, North Italy to Sweden. Biology. This species occurs only in the nests of its host Tetramorium caespitum. Workers and brood of both host and parasite are present but only the sexuals of Strongylognathus are developed, the original Tetramorium queen as well as the adoptive Strongylognathus queen usually being found present together. S. testaceus workers are normally greatly outnumbered by Tetramorium workers. Observations on this and related species suggest that neighbouring nests of the host species are raided to recruit more Tetramorium pupae to the colony which is often very populous with up to 20,000 individuals. Alatae are present in July and August

Published as part of Collingwood, C. A., 1979, The Formicidae (Hymenoptera) of Fennoscandia and Denmark., pp. 1-174 in Fauna Entomologica Scandinavica 8 on pages 80-82, DOI: 10.5281/zenodo.26691