Lasius humilis

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Lasius humilis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Lasiini
Genus: Lasius
Species: L. humilis
Binomial name
Lasius humilis
Wheeler, W.M., 1917

Lasius humilis casent0005407 profile 1.jpg

Lasius humilis casent0005407 dorsal 1.jpg

Specimen labels

This ant is typically found by locating nesting chambers under objects on the ground (e.g., rocks or logs). It occurs in a variety of habitats, at high elevations (~2,000 m +).

Identification

This small, pale yellow Lasius has very small eyes. The promesonotal suture is absent and the dorsal crest of the petiole when viewed from the front is wedge-shaped, tapering to form an angular, non-emarginate median prominence.

Key to Lasius workers, queens

Keys including this Species

Distribution

Western United States.

Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Beyond collection record details reported in a number of publications not much is known about the biology of this species.

Wilson (1955): "Dr. Cole has kindly supplied me with the following notes on his Colorado and New Mexico collections. The Trinidad, Colo., colony was found under a stone in the moist soil of a mountain meadow. The Tesuque Canyon, N. Mex., colony was found under a stone in moist, open pine-aspen woods."

Allred (1982): "Forty five ants in two collections were found under logs, one in grass, herbs, aspen, and pine, and one in pine" (Utah records).

Gregg (1963): "This ant is extremely rare, and though the majority of the records to date are from Colorado, they by no means indicate that the center of its geographic range lies within this state. We now know that the ant is distributed over a wide area in the Rocky Mountains and Great Basin Region, but from the little that has been learned of its ecology, it seems likely the range is a discontinuous one in widely isolated localities which happen to provide the required environmental conditions.

In addition to the record we possess from canyon meadow in Castle Park, Dr. Cole's specimens from south of Trinidad were living under a stone in moist mountain-meadow soil. Cole's New Mexico record came from Tesuque Canyon, Hyde State Park, near Santa Fe, at an elevation of 8700 ft., and was again under a stone but in moist pine-aspen woods. The conditions under which Wheeler's Salida specimens were obtained seems not to be known.

The Colorado stations all are in the Upper Sonoran Zone, as far as I can tell, although Cole's Trinidad record would appear to be just on the border of the Transition, but until an unequivocal site for this ant in the submontane of Colorado is established I prefer to leave its zonal distribution as stated above. Although our actual altitudinal records for humilis in Colorado do not state elevations as high as 7000 feet, Wheeler's specimens from Salida must of necessity be from this altitude at the minimum."

Mackay and Mackay (2002) - Occurs in sagebrush, pinyon-juniper, mountain meadows, pine aspen woods, ponderosa pine forests. This species nests under stones. Reproductives were found in nests in early July, flights occur at night in mid July (blacklight traps), and a loose gynes were collected in pitfall traps from early July to mid August.

Castes

Queen

Male

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • humilis. Lasius (Formicina) humilis Wheeler, W.M. 1917a: 528 (w.q.) U.S.A. Combination in L. (Chthonolasius): Emery, 1925b: 233. See also: Wilson, 1955a: 185.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Wilson (1955) - This caste by itself may at first be confused with nanitic workers of Lasius umbratus, but differs in the obliteration of the promesonotal impression and in the unusual petiole shape.

(1) Very small; extreme PW range of all series examined 0.53-0.63 mm.

(2) Promesonotal impression seen in side view very feeble or lacking.

(3) Eyes small relative to head; EL range 0.12-0.15 mm.

(4) Dorsal crest of the petiole in frontal view wedge-shaped, tapering upward to form an angular, non-emarginate median prominence.

(5) Body color uniformly light yellow.

Queen

Wilson (1955) - (1) The smallest North American Chthonolasius known; HW of the three syntype queens measured 1.04, 1.06, and 1.06 mm, respectively.

(2) Scapes longer relative to head width than in any other small Chthonolasius; SI of syntypes 85, 88 and 90 respectively, whereas in Lasius umbratus, Lasius rabaudi, Lasius minutus, and Lasius bicornis SI probably never exceeds 82 or 83 and is usually less than 80.

(3) Standing hairs absent from the appendages and sparse on the body. Seen in full face, no more than one or two standing hairs project beyond the entire cephalic contour posterior to the mandibular insertions. Gastric pilosity short and fine; gastric pubescence abundant and completely appressed.

(4) Body and appendages medium yellow, the occiput and thoracic dorsum lightly infuscate.

Type Material

Wilson (1955) - LECTOTYPE. By present selection, a queen in the Museum of Comparative Zoology labelled "Pyramid Lake, Nev. W. M. Mann." HW 1.04 mm, Additional syntype queens and workers are in the Museum of Comparative Zoology. A queen and two workers in the T. W. Cook Collection are probably also part of the original type series, despite their differing label "Pyramid Lake, Nev. 4-6-45."

References

  • Allred, D. M. 1982. Ants of Utah. Great Basin Naturalist. 42:415-511.
  • Gregg, R. E. 1963. The ants of Colorado, with reference to their ecology, taxonomy, and geographic distribution. University of Colorado Press, Boulder.
  • Emery, C. 1925d. Hymenoptera. Fam. Formicidae. Subfam. Formicinae. Genera Insectorum 183: 1-302 (page 233, Combination in L. (Chthonolasius))
  • Mackay, W. P. and E. Mackay. 2002. The ants of New Mexico (Hymenoptera: Formicidae). Edwin Mellen Press, Lewiston, NY.
  • Wheeler, W. M. 1917a. The mountain ants of western North America. Proc. Am. Acad. Arts Sci. 52: 457-569 (page 528, worker, queen described)
  • Wilson, E. O. 1955a. A monographic revision of the ant genus Lasius. Bull. Mus. Comp. Zool. 113: 1-201 PDF(page 185, see also)