Colobopsis impressa

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Bahamas.

Biology
Wheeler (1905) - Many specimens of all four phases from the keys along the course of the Southern Bight, Andros Island, and near Blue Hills, N. P. The colonies were all found nesting in the hollow culms of Cladium jamaicense along the damp edges of the “swashes.” The internode of the culm is perforated; by the ants with a circular opening, which is exactly occluded by the head of the soldier guarding the nest (Figs. V and W). Sometimes the nests extend over several internodes of the same stem, and in such cases there may be two or more circular openings guarded by as many soldiers. One dealated female was found in the act of starting her colony. Males and winged females were abundant in the nests taken in the Southern Bight, May 23, but were absent or rare in the colonies taken in New Providence as late as June 25.

Wheeler (1904) - workers of C. pylartes (= C. impressus) were occasionally seen running about singly on walnut leaves and twigs near Austin and New Braunfels. I was, however, unable to discover the nests in these localities. One day, while examining the dead limb of a hickory (Hicorea myristicaeformis) in the sandy post-oak woods at Delvalle, a few miles from Austin, I saw a worker run along the bark and enter a small round hole which a moment before had been closed by the circular head of a soldier. As soon as the worker had entered, the soldier moved forward and again closed the opening. Other workers were soon seen returning and anon disappearing into the nest after gently knocking at the living portal with their delicate antennae. This is an interesting demonstration of the existence of a purely tactile communication between ants, since the soldier's eyes and antennae are in such a position when the head is in the opening that sight and smell cannot be employed for the perception of workers approaching either from without or within the nest. Inasmuch as the soldier steps aside only when the tactile signal is given, that is, when the flat, truncated forehead is titillated by an incoming, or the tip of the gaster by an outgoing worker, and not when these surfaces are touched with a pin or a straw, we must suppose that some very simple form of tactile communication has been developed in these insects pari passu with the extraordinary adaptation of the soldier as sentinel and animated front door in one.

When the hickory limb was broken in two, the nest was found to consist of a number of irregular galleries, apparently in great part the abandoned tunnels of some beetle larva, immediately under the bark. The galleries contained larvae and nude pupae, besides a few dozen workers and soldiers and a single virgin female. I was unable to ascertain whether this nest was merely one of several belonging to a single colony spread over different parts of the tree, but on still further breaking the limb, which was only about two feet long and one and one half inches in diameter, I found it to contain also a fine nest of Colobopsis etiolata of essentially the same structure as the C. pylartes nest, except that the galleries extended into the hard wood, and a populous nest of Camponotus aethiops (as Camponotus marginatus) also excavated in the hard wood. Certainly these three species must have been very tolerant to excavate their nests in such close proximity to one another. In the bark of the same and surrounding trees I found nests of Temnothorax subditivus (as Macromischa subditiva), much like the nests of Leptothorax canadensis in our northern trees, and of Temnothorax affinis (as Leptothorax affinis) in Europe.

Nomenclature

 *  impressa. Colobopsis impressa Roger, 1863a: 160 (w.) U.S.A.
 * Mayr, 1886d: 423 (s.q.); Emery, 1893i: 681 (m.).
 * Combination in Camponotus (Colobopsis): Emery, 1889b: 517.
 * Combination in Colobopsis: Ward, Blaimer & Fisher, 2016: 350.
 * Status as species: Roger, 1863b: 10; Mayr, 1863: 459; Mayr, 1886d: 423; Cresson, 1887: 255; Dalla Torre, 1893: 235; Emery, 1893i: 681; Emery, 1896d 376 (in list); Wheeler, W.M. 1904b: 144 (redescription); Wheeler, W.M. 1910d: 353; Wheeler, W.M. 1910g: 572; Wheeler, W.M. 1913c: 117; Emery, 1925b: 147; Smith, M.R. 1930a: 6; Wheeler, W.M. 1932a: 16; Creighton, 1950a: 394; Smith, M.R. 1951a: 846; Smith, M.R. 1955b: 1; Smith, M.R. 1958c: 145; Smith, D.R. 1979: 1433; DuBois & LaBerge, 1988: 146; Deyrup, et al. 1989: 100; Bolton, 1995b: 104; Deyrup, 2003: 44; Coovert, 2005: 172; MacGown & Forster, 2005: 66; MacGown, et al. 2007: 12; McArthur, 2012: 70; Deyrup, 2017: 191 Mackay & Mackay, 2018: 144 (redescription).
 * Senior synonym of culmicola: Mackay & Mackay, 2018: 144.
 * Senior synonym of fraxinicola: Deyrup, 2017: 192 (in text); Mackay & Mackay, 2018: 144.
 * Senior synonym of hunteri: Mackay & Mackay, 2018: 144.
 * Senior synonym of pylartes: Deyrup, 2017: 192 (in text); Mackay & Mackay, 2018: 144.
 * culmicola. Camponotus (Colobopsis) culmicola Wheeler, W.M. 1905b: 117, figs. V, W; pl. 7, figs. 10, 11 (s.w.q.m.) BAHAMAS.
 * Wheeler, G.C. & Wheeler, J. 1953e: 190 (l.).
 * Combination in Colobopsis: Ward, Blaimer & Fisher, 2016: 350.
 * Status as species: Mann, 1920: 439; Emery, 1925b: 147; Smith, M.R. 1954c: 12; Kempf, 1972a: 42; Bolton, 1995b: 95; McArthur, 2012: 60.
 * Junior synonym of impressa: Mackay & Mackay, 2018: 144.
 * fraxinicola. Camponotus (Colobopsis) pylartes subsp. fraxinicola Smith, M.R. 1923a: 86 (s.w.) U.S.A.
 * Combination in Colobopsis: Ward, Blaimer & Fisher, 2016: 350.
 * Subspecies of pylartes: Creighton, 1950a: 394; Smith, M.R. 1951a: 846; Carter, 1962a: 7 (in list); Smith, M.R. 1967: 367; Smith, D.R. 1979: 1433; Bolton, 1995b: 100; McArthur, 2012: 158.
 * Junior synonym of impressa: Deyrup, 2017: 192 (in text); Mackay & Mackay, 2018: 144.
 * hunteri. Camponotus (Colobopsis) pylartes var. hunteri Wheeler, W.M. 1910d: 353 (s.w.) U.S.A.
 * Combination in Colobopsis: Ward, Blaimer & Fisher, 2016: 350.
 * Subspecies of pylartes: Wheeler, W.M. 1917a: 562; Emery, 1925b: 147; Smith, M.R. 1951a: 846.
 * Status as species: Creighton, 1950a: 393; Smith, M.R. 1958c: 145; Smith, D.R. 1979: 1433; Bolton, 1995b: 104; McArthur, 2012: 152.
 * Junior synonym of impressa: Mackay & Mackay, 2018: 144.
 * pylartes. Camponotus (Colobopsis) pylartes Wheeler, W.M. 1904b: 147, fig. 4 (s.w.q.) U.S.A.
 * Petralia & Vinson, 1980: 386 (l.).
 * Combination in Colobopsis: Ward, Blaimer & Fisher, 2016: 350.
 * Status as species: Wheeler, W.M. 1910d: 353; Wheeler, W.M. 1910g: 572; Wheeler, W.M. 1917a: 562; Emery, 1925b: 147; Smith, M.R. 1930a: 6; Wheeler, W.M. 1932a: 16; Creighton, 1950a: 394; Smith, M.R. 1951a: 846; Smith, D.R. 1979: 1434; Bolton, 1995b: 119; Deyrup, 2003: 44; McArthur, 2012: 156.
 * Junior synonym of impressa: Deyrup, 2017: 192 (in text); Mackay & Mackay, 2018: 144.

Type Material
Camponotus pylartes

Described from seven soldiers, numerous workers and a single female taken June 26 from a nest in a dead hickory branch (Hicorea myristicaeformis) at Delvalle, near Austin, Texas. I have also taken single workers running on the leaves and twigs of walnut trees near Austin and at New Braunfels, Texas. Among the specimens captured at Delvalle are two individuals that are clearly intermediate in structure of head and size of body between the soldier and worker; in other words, they are true mediae. (Wheeler 1904)

Taxonomic Notes
Wheeler (1905) - It is doubtful whether C. culmicola should be regarded as more than a subspecies of Colobopsis impressa of Florida. The soldier of the new form is larger, and has a less convex and thickset thorax, but the other differences may be unimportant. C. culmicola differs from Colobopsis pylartes of Texas in not having inflated cheeks or yellow bands on the gaster in the soldier and worker, though these bands are present in the female. It would be permissible to regard C. pylartes also as a subspecies of C. impressa.

Worker
Wheeler (1904) - Major Length, 4.3-4.6 mm.

Head subcylindrical, from above rectangular, but little longer than broad, sides parallel, occipital border convex, anterior truncated surface concave, its edge distinctly carinate along the sides, but rounded above in the clypeal and adjacent regions. Mandibles small, with flattened lower surfaces, 4-toothed, with a short toothless proximal portion to the blade. Clypeus on the truncated surface twice as long as broad, slightly broader above, extending onto the dorsal surface of the head as a transversely oblong piece about three times as broad as long. There is a distinct median keel running the full length of the clypeus. Frontal carina:: far apart, distinctly converging in front, somewhat convex externally. Eyes moderate, flattened, their anterior orbits about a third the distance from the posterior border of the head to the tips of the mandibles. Antennal scapes curved, slender at the base, gradually enlarging towards their tips, which extend beyond the posterior corners of the head to a distance about equal to their transverse diameter. All the funicular joints except the first, subequal, a little longer than broad, first joint nearly as long as the second and third together. Thorax robust, pronotum broader than fong, very convex and rounded, and forming a sphere with the mesonotum. Mesoepinotal constriction broad and pronounced. Epinotum with short convex basal, and longer, somewhat concave declivous surfaces, the angle between the two being rather blunt. Petiole low, convex and rounded in front and above, flattened behind, the posterior dorsal edge of the node being distinctly impressed in the middle, but not excised or emarginate. Gaster rather broad, flattened dorso-ventrally. Legs short, femora compressed, anterior pair distinctly dilated.

Mandibles opaque, finely punctate, longitudinally and obscurely rugose. Anterior two-fifths of head subopaque, coarsely and rather regularly reticulate-rugose, the spaces enclosed by the rugae being densely punctate. On the front and cheeks the sculpture passes over into shallow umbilicately punctate foveolae. Behind this region there is a narrow uniformly punctate zone both on the cheeks and front. Posterior portion of head and remainder of body shining, delicately but distinctly shagreened.

Cheeks and anterior dorsal surface of head with short, erect, obtuse, brown hairs. There are a few erect hairs on the vertex and on the gastric segments, especially along their posterior edges, and a few at the tips of the antennal scapes and femora. The legs are sparsely covered with minute, appressed white hairs.

Thorax and appendages dark brown, the former with yellowish sutures, gaster and posterior two-thirds of head black; anterior third of head light yellowish brown. Mandibular teeth black.

Minor Length, 3.5-4.5 mm.

Head but little longer than broad, a little broader behind than in front, cheeks convex. Mandibles small, 4- to 5-toothed, when closed their external margins form a straight line at right angles to the long axis of the head. Clypeus nearly square, obscurely keeled. Frontal carinre converging in front. Antennae more slender and proportionally longer than in the soldier, surpassing the posterior corners of the head by about one third their length. Thorax and petiole resembling the corresponding parts of the soldier. Gaster proportionally smaller and more pointed.

Body and appendages shining, distinctly shagreened, the head and thorax more coarsely than the gaster; the cheeks and upper surface of the head also with scattered punctures.

Cheeks and legs covered with delicate, appressed, white hairs. Clypeus, front, vertex, tips of antennre and femora and the gastric segments with a few scattered and longer brown hairs.

Dark brown, head and gaster black, mandibles yellow, anterior portions of cheeks and clypeus, antennae and legs, pale brown.

Camponotus culmicola

Soldier Length 5.3-6.5 mm.

Very closely related to Colobopsis impressa Roger and C. pylartes Wheeler. Head subcylindrical, rectangular from above, a little longer than broad, sides parallel, occipital border straight, with rounded angles; anterior truncated surface concave with distinctly carinate edge on the sides, but rounded in the clypeal and adjacent regions. Mandibles with a convex ventral border, four teeth, and a short toothless proximal portion to the blade. Clypeus on the truncated surface nearly twice as long as broad, broadest above, extending on to the dorsal surface of the head as a transversely oblong piece (twice as long as broad. A median carina runs the full length of the clypeus. Frontal carinae far apart, distinctly converging anteriorly, slightly convex exteriorly. Eyes moderate, flattened, their anterior orbits about X the distance from the posterior corner of the head to the tip of the mandibles. Antennal scapes slender, curved at the base, enlarging towards their tips which exceed the posterior corners of the head by a distance about equal to their transverse diameter. Funicular joints subequal, except the first, which is nearly as long as the two succeeding joints together. Thorax more robust than that of C. pylartes, but less robust than that of C. impressa. Pronotum as long as broad, mesonotum nearly as long as broad. Mesoepinotal constriction deep and long; basal epinotal surface slightly convex, a little longer than the flattened declivity with which it forms almost a rounded right angle. Petiole very low, with a subcuboidal node, distinctly impressed in the middle above and behind. Gaster large, oblong elliptical, somewhat flattened dorsoventrally. Legs short, femora compressed, anterior pair distinctly dilated.

Mandibles opaque, finely punctate and obscurely reticulate-rugose. Anterior half of head subopaque, coarsely and rather regularly reticulate-rugose, the interrugal spaces being densely punctate. On the front and cheeks the sculpture passes over into shallow, umbilicately punctate foveola. Behind this region the surface for a short distance is very finely and densely punctate. Remainder of head and body shining, very finely but distinctly shagreened; meso- and epinotum subopaque.

Cheeks and anterior dorsal surface of head with short, erect, obtuse yellowish hairs. There are also a few erect white hairs on the vertex, tips of antennal scapes and femora, and on the gastric segments.

Dark brown, posterior two thirds of head darker, gaster and mandibular teeth black; remainder of mandibles and anterior third of head yellowish brown.

Minor Length 4-4.5 mm.

Head a little longer than broad, slightly broader behind than in front, cheeks convex. Mandibles 5-toothed, when closed having their outer borders more projecting than in the worker of C. impressa. Clypeus nearly square, obscurely keeled. Frontal carina converging in front. Antenna more slender and proportionally longer than in the soldier, extending about their length beyond the posterior corners of the head. Thorax and petiole resembling the corresponding parts of the soldier. Gaster proportionally smaller and more pointed.

Body and appendages subopaque, gaster and posterior portion of head shining; whole surface shagreened, more sharply on the head and thorax, so that these parts have a silky lustre. Cheeks and front with indistinct, scattered punctures.

Hairs and pubescence white, very sparse; the former confined to the head and gaster, the latter most conspicuous on the cheeks and legs. Dark brown, antennae somewhat paler in some specimens; gaster black, immaculate.

Camponotus pylartes

Major Length, 4.5-5 mm.

Head subcylindrical, somewhat longer than broad, decidedly wider in front than behind, with inflated cheeks; occipital border straight or slightly concave. Anterior truncated surface oblique, in profile distinctly concave, with a sharp border only on the sides of the face and mandibles; on the clypeal and adjacent regions the truncated passes into the dorsal surface through a rounder angle than in 'C. impressa''. Mandibles larger than those of C. impressa, with more convex ventral margins; blade with four distinct apical teeth and a toothless basal portion. Eyes, clypeus, frontal carinre and antennre as in C. impressa. Thorax distinctly narrower and less robust, the pronotum being fully as long as broad and forming an ellipsoid with the mesonotum when seen from above; dorso-ventral diameter of the pro- and mesonotum much shorter than in C. impressa. The mesoepinotal constriction is shallower, though pronounced, the angle formed by the basal and declivous surfaces of the epinotum is more acute, and the former surface is longer and flatter. Petiole low, robust, as broad above as below, its anterior and posterior surfaces straight and parallel, the former passing over roundly into the flat top of the node when seen in profile; from above the node is convex in front and flattened behind. From behind it is somewhat more distinctly impressed in the middle above than in C. impressa. Gaster and legs as in that species.

Mandibles and anterior third of head subopaque, the former obscurely longitudinally rugose-punctate, the latter regularly and coarsely reticulate-rugose, with punctate interrugal spaces. Posteriorly this sculpture passes gradually into shallow and more scattered, umbilicately punctate foveolae on the front and cheeks. Posterior half of head and remainder of body shining, finely shagreened.

Hairs yellowish, short, erect and obtuse on the anterior half of the head, except its truncated surface, longer and tapering on the front and vertex. Gaster with scattered tapering hairs which are most abundant on the terminal segments. There are a few hairs at the tips of the antennal scapes and femora, and minute, appressed white hairs on the femora and tibiae.

Thorax and appendages yellowish brown; posterior two-thirds of head dark brown, gaster black, with the basal fourth of the first and second and sometimes of the third segment, yellow. Femora, tibiae and upper surface of the thorax sometimes darker than the lower portions of the thorax. Mandibular teeth black.

Minor Length 3-4 mm.

Mandibles when closed more projecting than in C. impressa. Clypeus and anterior portion of head less convex. Antennal scape surpassing the posterior angle of the head by nearly half its length. Thorax resembling that of the soldier, low through the pro- and mesonotum, which are also narrower than in the worker C. impressa. Basal epinotal surface long and flattened, the declivity shorter and concave, the two surfaces meeting at a right angle. Petiole and legs as in the soldier. Gaster proportionally shorter and more pointed.

Shining throughout and finely shagreened, the front and cheeks also faintly and sparsely punctate, the sculpture throughout being somewhat fainter than in the worker '"C. impressa''.

Hairs white, sparse; long and erect on the clypeus, front and gaster, minute and appressed on the cheeks and legs.

Yellowish brown; head, gaster, apical third of funiculus, femora and tibiae, dark brown or black; base of first and second gastric, segments, mandibles, anterior portions of cheeks and clypeus, yellow.

Queen
Wheeler (1904) - Length, 6 mm.

Head like that of the soldier but less robust. Petiole as in the soldier, with a low, thick, four-cornered node, which is broader than high.

Sculpture and pilosity as in the soldier.

Ferruginous, in part yellowish red. Mesonotum, except for two yellow longitudinal lines, the scutellum and the middle of the epinotum, light brown; gaster brownish black, the anterior two-thirds of the first and second segments yellow.

Camponotus culmicola

Length 6.5-7 mm.

Head like that of the soldier but more elongate and without carinate edges to the truncated portion in the region of the cheeks. Antennal scapes projecting about twice as far beyond the posterior corners of the head. Sculpture and pilosity as in the soldier.

Dark brown; gaster black; anterior fourth of the head yellowish; articulations of the thorax and legs whitish; first, second, and third gastric segments yellow at the base; the lighter colof confined to the extreme base of the first segment, broad and conspicuous on the second, and on the third very narrow and often concealed, except at the sides, by the posterior edge of the second segment; ventral surfaces of the first and second segments more or less yellow. Wings whitish hyaline, with very pale yellow veins and stigma.

Camponotus pylartes

Length 5.5 mm.

Head resembling that of the soldier, but somewhat more slender, with ocelli, slightly larger eyes and less inflated cheeks. Thorax hardly two and one half times as long as broad, mesonotum about as broad as long. There is a close resemblance to the soldier in the sculpture and pilosity. Anterior half of head brownish yellow with dark brown clypeal sutures and external mandibular borders. Teeth of mandibles black. Posterior half of head dark brown. Thorax and petiole yellow, pro- and mesonotum, scutellum and pleurae clouded with pale brown. Gaster black, basal and dorsal half of first and second segments, basal fourth of third segment and entire ventral portions of first and second segments, pale yellow. Coxae yellow, remainder of legs and antennae brown. Wings whitish hyaline, with pale yellow veins and stigma.

Male
Wheeler (1904) - According to Emery "very similar to the South European C. truncates in form and coloration, but somewhat smaller (4-4.5 mm.); in other respects hardly distinguishable.

Camponotus culmicola

Length 4-4.5 mm.

Head, including the mandibles, a little longer than broad, with prominent eyes and ocelli; cheeks slightly converging anteriorly, posterior corners broadly rounded. Mandibles pointed, toothless, overlapping when closed. Clypeus sharply keeled. Antennae slender; scape more than half as long as the funiculus, which is filiform and consists of subequal joints, with the exception of the conspicuously incrassated first joint. Thorax robust; mesonotum longer than broad, forming a regular ellipse with the scutellum. Epinotum steep, evenly rounded, so that basal and declivous surfaces are indistinguishable. Petiole very low, longer than high, thick and blunt above, somewhat impressed in the middle. Legs and gaster slender, the latter with slender genital appendages.

Shining throughout, finely shagreened, especially on the head and thorax.

Hairs whitish, much scattered, suberect, confined to the head and gaster. Pubescence lacking except on the antennal scapes.

Dark brown; head nearly black; mandibles, genitalia, articulation of the antennae, legs, thorax, and gaster sordid yellow. Wings like those of the female.