Lasius brevicornis

A common and wide ranging species that exhibits regional variation in its nesting and habitat preferences. In New England, it is a subterranean ant which nests under rocks in open habitats and dry woodlands (Ellison et al., 2012). It is a generalist predator that also tends root aphids and feeds on their honeydew. Mating flights occur in late August and early September.

Identification
This is a yellow or pale brown species, with a small eye (fewer than 35 ommatidia). The apex of the petiole is either straight or slightly concave. The hairs on the scapes and tibiae are decumbent or appressed (possibly 1 or 2 suberect hairs). The last segment of the maxillary palp is about as long (or shorter) than the penultimate segment. (United States: Mackay and Mackay 2002)

Ellison et al., (2012) - This is one of two New England species of Lasius with very tiny eyes; the other is Lasius nearcticus. These two species nest in distinct habitats – L. flavus in open, dry habitats and L. nearcticus in moist forests – but they can be distinguished reliably only by examining their maxillary palps at 25 – 50× magnification under a dissecting microscope. In L. flavus, the last (terminal) segment of the palp is shorter than the next-to-last (penultimate) segment, whereas in L. nearcticus, the terminal segment of the palp is longer than the penultimate segment.

Distribution
This species is abundant in the eastern United States, but it is rare in the Gulf Coast states. It has been collected occasionally in the northern Rocky Mountains, the Chiricahua Mountains of southeast Arizona, and the Pacific Northwest. It is widespread in New England (Ellison et al., 2012).

Distribution based on Regional Taxon Lists
Nearctic Region: Canada, United States.

United States
In New Mexico (Mackay and Mackay 2002) this species nests under stones. Reproductives were found in the nest in mid August. It tends aphids, especially on the roots of grasses. Occurs in grasslands and mixed deciduous forest to ponderosa pine-riparian.

Nomenclature

 *  brevicornis. Lasius brevicornis Emery, 1893i: 639, pl. 22, fig. 22 (w.q.m.) U.S.A.
 * [Note: type-locality designated as District of Columbia by Creighton, 1950a: 421.]
 * Combination in Lasius (Formicina): Wheeler, W.M. 1916k: 172; Wheeler, W.M. 1917i: 463.
 * Combination in Lasius (Lasius): Emery, 1925b: 231.
 * Junior synonym of flavus: Wilson, 1955a: 112; Smith, D.R. 1979: 1437.
 * Status as species: Wheeler, W.M. 1904e: 305; Wheeler, W.M. 1905f: 396; Wheeler, W.M. 1906b: 13; Wheeler, W.M. 1908f: 623; Wheeler, W.M. 1910g: 569; Wheeler, W.M. 1916k: 172; Wheeler, W.M. 1916m: 593; Wheeler, W.M. 1917a: 526; Wheeler, W.M. 1917i: 463; Emery, 1925b: 231; Smith, M.R. 1930a: 5; Smith, M.R. 1931a: 23; Wheeler, W.M. 1932a: 17; Menozzi, 1932b: 311; Cole, 1936a: 37; Wing, 1939: 164; Wesson, L.G. & Wesson, R.G. 1940: 100; Wheeler, G.C. & Wheeler, E.W. 1944: 252; Buren, 1944a: 296; Creighton, 1950a: 421; Smith, M.R. 1951a: 851; Schar et al., 2018: 6.
 * microps. Lasius (Formicina) brevicornis var. microps Wheeler, W.M. 1917a: 526 (w.) U.S.A.
 * Wheeler, G.C. & Wheeler, J. 1953c: 152 (l.).
 * Combination in L. (Chthonolasius): Creighton, 1950a: 422.
 * Subspecies of brevicornis: Wheeler, G.C. & Wheeler, E.W. 1944: 253
 * Subspecies of flavus: Creighton, 1950a: 422.
 * Junior synonym of flavus: Wilson, 1955a: 112.
 * Junior synonym of brevicornis: Schar et al., 2018: 6.
 * claripennis. Lasius (Formicina) flavus subsp. claripennis Wheeler, W.M. 1917a: 527 (w.q.m.) CANADA.
 * Junior synonym of microps: Creighton, 1950a: 422.
 * Junior synonym of brevicornis: Schar et al., 2018: 6.
 * helvus. Lasius helvus Cook, 1953: 326, figs. (w.) U.S.A.
 * [Also spelled helveolus, on p. 327.]
 * Junior synonym of flavus: Wilson, 1955a: 113.
 * Junior synonym of brevicornis: Schar et al., 2018: 6.

Taxonomic Notes
Schar et al. (2018): Lasius brevicornis Emery, 1893 stat. nov. was treated as a full species until it was placed in synonymy with ''La. flavus'' by Wilson (1955). This study supports its removal from synonymy and treatment as a full species. The junior synonyms Lasius brevicornis microps Wheeler, 1917, Lasius flavus claripennis Wheeler, 1917 and Lasius helvus Cook, 1953 should be transferred from synonymy with Lasius flavus and treated as junior synonyms of Lasius brevicornis.