Lasius umbratus

Identification
Clear yellow to reddish yellow; funiculus segments 2 to 4 slightly longer than wide. Scape elliptical in cross section. Petiole tapering to dorsal crest which is usually emarginate. Body surface and appendages covered in adpressed silvery pubescence. Longest hairs on gaster 0.06 mm to 0.11 mm, about half maximum hind tibial width. Erect hairs on genae, scapes and tibiae numerous. Length: 3.8-5.5 mm (Collingwood 1979).

Distribution
Throughout Europe, widely distributed and not uncommon (Collingwood 1979).

This taxon was described from Finland.

Biology
This species nests under boulders, in tree stumps and at the base of old trees. Workers are subterranean and seldom or never seen above ground. Flight period from mid August to late September. Single queens found colonies by invasion of and adoption in Lasius niger, Lasius alienus or occasionally Lasius brunneus nests. In late summer dealate queens often wander over the surface of L. niger nests, sometimes carrying a dead L. niger worker as a prelude to securing adoption.

Nomenclature

 *  umbratus. Formica umbrata Nylander, 1846b: 1048 (q.m.) FINLAND. Schenck, 1852: 59 (w.); Hauschteck, 1962: 219 (k.); Hung, 1969: 456 (k.). Combination in Lasius: Mayr, 1861: 50; in Donisthorpea: Donisthorpe, 1915d: 223; in Formicina: Emery, 1916b: 241; in Acanthomyops: Ruzsky, 1925b: 44; in Chthonolasius: Ruzsky, 1936: 91; in Lasius (Chthonolasius): Ruzsky, 1914a: 59; Müller, 1923: 129; Emery, 1925b: 233; Wilson, 1955a: 150. Senior synonym of belgarum: Wilson, 1955a: 150; Seifert, 1988a: 150; of hirtiscapus: Wilson, 1955a: 150; Seifert, 1990: 11; of affinoumbratus, aphidicola, epinotalis, exacutus, nyaradi, osakana, silvestrii and material of the unavailable names mixtoaffinis, mixtobicornis referred here: Wilson, 1955a: 150; of mixtoumbratus: Wilson, 1955a: 150; Kutter, 1977c: 14. See also: Stitz, 1939: 291; Bernard, 1967: 363; Kutter, 1977c: 232; Yamauchi, 1979: 168; Seifert, 1988a: 150; Atanassov & Dlussky, 1992: 245; Radchenko, 2007: 34.
 * aphidicola. Formica aphidicola Walsh, 1863: 310 (w.q.m.) U.S.A. Wheeler, G.C. & Wheeler, J. 1953c: 150 (l.). Combination in Lasius: Mayr, 1886d: 429; in L. (Chthonolasius): Ruzsky, 1914a: 61. Junior synonym of flavus: Mayr, 1886d: 429. Revived from synonymy: Dalla Torre, 1893: 182. Subspecies of umbratus: Wheeler, W.M. 1908g: 406; Buren, 1944a: 297. Junior synonym of umbratus: Wilson, 1955a: 150.
 * exacutus. Lasius umbratus var. exacutus Ruzsky, 1902d: 15 (w.) RUSSIA. Combination in Acanthomyops: Ruzsky, 1925b: 44; in Lasius (Chthonolasius): Ruzsky, 1914a: 61; Emery, 1925b: 234. Subspecies of umbratus: Ruzsky, 1905b: 287. Raised to species: Ruzsky, 1925b: 44. Subspecies of bicornis: Menozzi, 1939a: 314 (in key). Junior synonym of umbratus: Wilson, 1955a: 150.
 * affinoumbratus. Lasius umbratus var. affinoumbratus Donisthorpe, 1914: 40 (w.) GREAT BRITAIN. Junior synonym of umbratus: Wilson, 1955a: 151.
 * belgarum. Formicina belgarum Bondroit, 1918: 31, fig. 17 (w.q.) BELGIUM. Combination in Lasius (Chthonolasius): Emery, 1925b: 234. Subspecies of umbratus: Stärcke, 1937: 57; of mixtus: Stitz, 1939: 299. Junior synonym of umbratus: Wilson, 1955a: 151; Seifert, 1988: 150.
 * silvestrii. Lasius (Chthonolasius) silvestrii Wheeler, W.M. 1928d: 120 (q.) JAPAN. Junior synonym of umbratus: Wilson, 1955a: 152.
 * hirtiscapus. Lasius umbratus var. hirtiscapus Stärcke, 1937: 43 (q.) CZECHOSLOVAKIA. Subspecies of mixtus: Stitz, 1939: 299. Junior synonym of umbratus: Wilson, 1955a: 152.
 * osakana. Lasius (Chthonolasius) silvestrii var. osakana Santschi, 1941: 278 (q.) JAPAN. Junior synonym of umbratus: Wilson, 1955a: 152.
 * nyaradi. Chthonolasius affinis var. nyaradi Röszler, 1943: 47 (w.q.) ROMANIA. Junior synonym of umbratus: Wilson, 1955a: 152.
 * epinotalis. Lasius (Chthonolasius) umbratus subsp. epinotalis Buren, 1944a: 297 (w.) U.S.A. Junior synonym of umbratus: Wilson, 1955a: 152.

Additional References

 * Collingwood, C. A. 1979. The Formicidae (Hymenoptera) of Fennoscandia and Denmark. Fauna Entomol. Scand. 8:1-174.