Camponotus laevigatus

Camponotus laevigatus is less common than other forest dwelling North American carpenter ants that have both large colonies and large soldiers. The size of mature colonies is uncertain. A single nest collected in Washington state was estimated to contain about 1,000 individuals but Akre et al. (1994) speculated that colonies may contain ten to twenty times as many workers. Individuals forage during the day and do not use regular trails (Hansen and Akre 1985).

Identification
This species is easily separated from all other North American Camponotus species by the majors, minors, females, and males being shiny black and having short, bristly hairs on the antennal scapes as well as other body parts. The males may be easily recognized by the abundant, white, erect hairs on many body parts including the head, scape, mesosoma, petiole, gaster, and tibiae. (Mackay and Mackay 2002)

The workers are polymorphic, with a large soldier caste.

Distribution
Canada, United States, Mexico. Montana west to British Colombia, south to California and Baja California Norte, and east to New Mexico.

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

Biology
Wheeler (1910) - C. laevigatus is a mountain ant peculiar to the high ranges of the western states. It extends into Mexico and also for a short distance into British America (Vancouver Island, according to Lord). I believe that it will rarely be found below an altitude of 6000 ft. I have seen it only at elevations of 7000-8000 ft. in the mountains of Colorado. It forms large colonies which nest in dry stumps or logs after the manner of Camponotus herculeanus and its various subspecies and varieties. In behavior it closely resembles the south European Camponotus vagus.

Gregg (1963) reports from Colorado: "..this species is closely associated with wooded and forested areas and forest margins, not being found at any great distances from them in open habitats. It requires rotting logs in various degrees of decomposition, especially the early stages, although if more records were available the ant might be seen to utilize a greater assortment of decaying woods. My general impression is that laevigatus shows a preference for rather sound pine logs in the second to third stages of disintegration."

Mackay and Mackay (2002) - Deciduous forests, oak forests (Gamble), pinyon-juniper, fir and pine forests at higher elevations or latitudes, 2130 - 2447 meters in elevation. Nests are occasionally found in urban areas. Camponotus laevigatus is a forest species that nests in rotten logs and stumps. It is an occasional pest in buildings.Brood was found in nests in August, new nests were established in August. They are prey of Pogonomyrmex montanus in southern California.

Nevada, Wheeler and Wheeler (1986) - We have 11 records from 11 localities, which are widely scattered throughout the state, except none in the northwest; 4,600-8,600 ft. Five records were from the Coniferous Forest Biome and 1 from Pinyon-Juniper. Two were reported nesting in prostrate coniferous trunks and 1 was in the wood of an abandoned mine building.

Nomenclature

 *  laevigatus. Formica laevigata Smith, F. 1858b: 55 (w.q.) U.S.A. Wheeler, W.M. 1910d: 327 (s.m.); Wheeler, G.C. & Wheeler, J. 1968: 216 (l.). Combination in Camponotus: Roger, 1863b: 5; in C. (Camponotus): Forel, 1914a: 266. See also: Mayr, 1886d: 420.

Worker
Wheeler (1910) – Major Length, 10-13 mm.; head, 3.4 x 3.4 mm.; scape, 2.7 mm.; hind tibia, 3.2 mm.

Head as broad as long. somewhat broader behind than in front, with very round, convex sides and posterior corners and scarcely excised posterior border. Eyes small. flat. Mandibles convex, 5-toothed. Clypeus short, evenly convex, without a carina, its anterior border not produced, with a shallow, rounded median excision and a slightly deeper and more angular excision on each side. Frontal area obsolete, frontal groove distinct. Antennae with short scapes, not reaching beyond the posterior corners of the head, neither flattened nor dilated at the base, distinctly enlarged at the tips. Thorax robust and rather high, narrower than the head in front, laterally compressed behind, evenly arched above in profile, epinotum with subequal base and declivity meeting in a rounded, obtuse angle. Petiole high, compressed anteroposteriorly, with feebly convex anterior and flattened posterior surface; border entire, evenly rounded and rather blunt. Gaster of the usual shape. Legs of moderate length; middle and hind tibiae neither compressed nor sulcate, elliptical in cross section.

Entire surface smooth and shining; mandibles coarsely striato-punctate.

Head, thorax, scapes and legs covered with scattered, rather small, but deep punctures; intermingled with these on the cheeks, clypeus, front and vertex, there are large but equally scattered punctures or foveolae, those on the cheeks being elongated. Gaster very finely, transversely shagreened and with scattered, piligerous punctures. Pubescence apparently jacking.

Hairs white or pale yellow, delicate, abundant, short and erect on the body, longest on the gaster. Antennal scapes and legs with numerous short, erect hairs. Flexor surfaces of middle and hind tibiae with a few short bristles at their distal ends.

Deep black throughout; mandibles, clypeal border and cheeks rarely deep red; tarsi brownish towards their tips; posterior edges of the gastric segments dull brown.

Minor Length, 7-9 mm.

Queen
Wheeler (1910) - Length, 13-15 mm.

Very similar to the worker major. Sides of head less. convex. Epinotum with flattened base, shorter than the abrupt, concave declivity. Petiole even more compressed anteroposteriorly than in the worker major, with sharper border, narrowed and feebly excised above. Wings long (15 mm.), strongly tinged with brown; veins and stigma brown.

Head similar to that of the worker major, but little longer than broad, with less convex sides, short and broadly rounded behind. Eyes feebly convex. Clypeus subcarinate. Antennal scapes extending about one-third their length beyond the posterior corners of the head. Epinotum and petiole like those of the worker major, but basal surface of the former longer in proportion to the length of the declivity.

Sculpture, pilosity and color as in the worker major.

Male
Wheeler (1910) - Length, 9-10 mm.

Head, including the eyes, about as broad as long, evenly rounded and broadest behind; cheeks subparallel, slightly concave, about as long as the eyes. Mandibles edentate. Clypeus convex, but scarcely carinate, with broadly rounded, entire anterior border. Ocelli very small. Antennae long and slender; first funicular joint Incrassated distally, a little longer than the second. Thorax robust; epinotum convex, sloping, without distinct basal and declivous surfaces. Petiole thick, rather high, transverse, evenly rounded and blunt, slightly impressed in the middle above. Gaster slender. Legs long, with long tarsal claws and very large empodia.

Surface of body very finely and densely shagreened; mandibles, head, pro- and mesonotum subopaque, remainder of thorax, gaster and legs shining.

Pilosity similar to that of the worker, but less abundant. absent on the scapes and thorax, with the exception of the epinotum. Pubescence very short and dilute, but visible on the head, thorax and gaster.

Black; mandibles, antennal funiculi, tarsi and articulations of the legs brown; wings colored like those of the female.

Type Material
Wheeler (1910) - The types of this species, which is very constant and easily recognized by its deep black color, smooth surface and peculiar pilosity, came from California.

Etymology
Morphological. laevigatus means smooth or slippery and this describes the ant's shiny integument.

References based on Global Ant Biodiversity Informatics

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