Strongylognathus testaceus

This species is a slave-maker and is only found in nests with its hosts and. It occurs in a range of habitats including steppe habitats and pine forests in Russia (Zryanin & Zryanina, 2007).

Identification
Yellowish brown. Head rectangular with pronounced occipital emargination and postero-lateral 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 (Collingwood 1979).

Distribution
Pyrenees to Ukraine, North Italy to Sweden (Collingwood 1979).

Distribution based on Regional Taxon Lists
Palaearctic Region: Andorra, Austria, Belarus, Belgium, Bulgaria, Croatia, Czech Republic, Georgia, Germany, Greece, Hungary, Iberian Peninsula, Lithuania, Netherlands, Poland, Republic of Moldova, Romania, Russian Federation, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkmenistan, Ukraine, United Kingdom of Great Britain and Northern Ireland.

Biology
Collingwood (1979) - 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.

Guillem et al., 2014 - S. testaceus is a degenerate slave-maker of Tetramorium caespitum and T. impurum. The Strongylognathus queen does not kill the host queen, but instead pheromonally inhibits production of the host sexual brood. As the number of parasite workers rarely exceeds 1%, they rarely (or perhaps never) raid additional colonies for extra slaves (Sanetra and Gusten, 2001; Czechowski et al., 2002; Tinaut et al., 2005). Thus, this species may be considered an intermediate stage between slave-makers and inquilines.

Nomenclature

 *  testaceus. Eciton testaceum Schenck, 1852: 117 (w.q.m.) GERMANY. Combination in Strongylognathus: Mayr, 1853d: 390. Senior synonym of emarginatus: Mayr, 1853d: 390; of diveri: Brown, 1955c: 113. See also: Baroni Urbani, 1971c: 151; Kutter, 1977c: 166; Atanassov & Dlussky, 1992: 156; Sanetra, Güsten & Schulz, 1999: 343.
 * emarginatus. Myrmus emarginatus Schenck, 1853: 188 (w.) GERMANY. Junior synonym of testaceus: Mayr, 1853d: 390.
 * diveri. Strongylognathus diveri Donisthorpe, 1936c: 113, figs. 1, 2, 7 (w.) GREAT BRITAIN. Junior synonym of testaceus: Brown, 1955c: 113.