Lasius crypticus

Identification
See the nomenclature section below.

Distribution
crypticus has its center of abundance in the Great Plains of the western U. S. It apparently stops abruptly at the edge of the eastern deciduous forest, having never been collected east of the eastern tier of counties of North Dakota. It is relatively common in the Rocky Mountains and Great Basin, and reaches as far west as California, Oregon and Washington.

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

Biology
Wilson (1955) - The following generalizations are based on a few of my own observations along with field notes supplied me by G. C. Wheeler, A. C. Cole, and Borys Malkin. crypticus is most abundant in prairies and tends to replace neoniger in the most dry, exposed situations. In eastern Montana and southern Idaho it was found thriving in a short-grass prairie-semidesert transition. At Cascade, Idaho, and in several localities in New Mexico, it was taken in open pine forest. At Green Canyon Hot Springs, Idaho, it was found in dry willow-poplar woods. In the great majority of cases it has been found nesting under stones, but occasionally (e.g. Donnelly and Cascade, Idaho) it constructs neoniger-like craters in open soil.

No nuptial flights of this species have been recorded. Winged reproductives have been taken with workers from July 9 (Great Falls, Mont.) to August 31 (holotype nest series, Pembina Co., N. Dak.). The majority of such records fall in the last half of July and first half of August. This would seem to be strong prima-facie evidence that the reproductive period of crypticus precedes that of neoniger.

Nomenclature

 *  crypticus. Lasius (Lasius) crypticus Wilson, 1955a: 104 (w.q.m.) U.S.A.

Description
A western North American species very similar to Lasius neoniger, differing principally in the scarcity of hairs on the scapes and fore tibiae, and by the darker body coloration of the worker and queen. Linked to the "neoniger complex" by the possession of clypeal and dentition characters detailed in the description of neoniger. Superficially resembles Lasius alienus and has been consistently determined as Lasius americanus by past authors.

(1) In all three castes standing hairs are invariably absent on the scapes and fore tibiae along the plane of count (seta count, q. v.), while appressed decumbent hairs are rare or absent. These surfaces are covered only by a short, predominantly appressed pubescence.

(2) The worker and queen are almost invariably dark brown, rarely medium brown, opposed to the typically light brown coloration of neoniger. The males of the two species show broadly overlapping dark brown coloration.

(3) The worker has a proportionately shorter scape length than in neoniqer, a small number of series of medium-sized to large workers, when measured, fell between the alienus-niger and brunneus SI-HW regression zones, while several nanitic series fell along the extrapolated brunneus zone. However, crypticus and neoniger are too close to give this character diagnostic value by itself.

Type Material
Wilson (1955) - HOLOTYPE. A worker in the MCZ, selected from a large nest series collected four miles north of Gardar, Pembina Co., N. Dak., Aug. 31, 1949, with associated winged queens and males (E. L. Krause leg., ace. no. 138). PW 0.52 mm., HW 0.79 mm., SL 0.70 mm., SI 90, EL 0.19 mm., seta count O. Paranidotypes are in the, , UMMZ, G. C. Wheeler Coll., Creighton Coll., and Cole Coll.