Camponotus herculeanus

This very common species normally nests in rotten logs and stumps, but nests are occasionally found under stones, especially incipient nests (as known from North America).

Identification
This is a common dark brown or black ant with a dark red petiole, antennae, legs, and base of first gastral segment. The scapes of the majors barely reach, or only slightly surpass the posterior lateral corners. Erect hairs are moderately abundant, being found specifically on the clypeus (along margins), on the dorsal surface of the head, ventral surface of the head, dorsal surface of the mesosoma, petiole and gaster, they are absent on the cheeks, scapes (except at apex) and tibiae (except for a double row on the flexor surface); appressed pubescence is sparse, and is limited to a few tiny hairs on the head, dorsum of the mesosoma, and dorsal surface of the gaster. The minors are similar except for size, having an oval shaped head, and the scapes extend well past the posterior lateral corners. The females are large, mostly black specimens. The scape extends more than 2 funicular segments past the posterior lateral corners. (Mackay and Mackay 2002)

Bicoloured with alitrunk dull red to reddish black, head and gaster dull black. Frons has deep close set punctures. Long pubescence on dorsum of first gaster tergite overlapping posterior border. Length: 5-12 mm (Collingwood 1979).

Distribution
Throughout mountain Europe and extending through Northern Eurasia from Norway to Eastern Siberia to the northernmost tree frontier in Arctic Norway (Collingwood 1979). Also northern North America.

Distribution based on Regional Taxon Lists
Nearctic Region: Canada, United States. Palaearctic Region: Andorra, Armenia, Austria, Belarus, Belgium, Bulgaria, China, Croatia, Czech Republic, Democratic Peoples Republic of Korea, Denmark, Estonia, Finland, Georgia, Germany, Greece, Hungary, Iberian Peninsula, Italy, Japan, Kazakhstan, Kyrgyzstan, Latvia, Liechtenstein, Lithuania, Luxembourg, Mongolia, Netherlands, Norway, Poland, Republic of Korea, Republic of Macedonia, Republic of Moldova, Romania, Russian Federation, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, Ukraine.

Europe
Collingwood (1979) - This species is a typical denizen of shaded coniferous forest nesting in rotten stumps and occasionally mining in living trees. Fertilised females found nests singly. Alatae are developed in the late summer but overwinter to swarm in June.

New Mexico
Mackay and Mackay (2002) - This very common species normally nests in rotten logs and stumps, but nests are occasionally found under stones, especially incipient nests. This species may form a plesiobiotic relationship with Formica neorufibarbis. Foragers tend several species of aphids on many different plant species. Reproductives and brood were present in the nests from June to August, reproductives until September. Foundress females were found from late June to October.

Nomenclature

 *  herculeanus. Formica herculeana Linnaeus, 1758: 579 (q.) EUROPE. Lepeletier de Saint-Fargeau, 1835: 209 (w.q.m.); Mayr, 1855: 308 (w.q.m.); Wheeler, G.C. & Wheeler, J. 1953e: 185 (l.). Combination in Camponotus: Mayr, 1861: 36; in C. (Camponotus): Forel, 1914a: 259. Senior synonym of atra, intermedia: Nylander, 1846a: 894; of castanea: Mayr, 1863: 399; of whymperi: Creighton, 1950a: 367; of nadigi: Yasumatsu & Brown, 1951: 30; of montanus, shitkowi: Emery, 1925b: 72; Karavaiev, 1936: 178; Arnol'di, 1967: 1819; of caucasicus: Arakelian, 1994: 85; of eudokiae: Radchenko, 1997a: 555. See also: Tarbinsky, 1976: 148; Kutter, 1977c: 204; Collingwood, 1979: 90; Smith, D.R. 1979: 1426; Atanassov & Dlussky, 1992: 210.
 * castanea. Formica castanea Lepeletier de Saint-Fargeau, 1835: 215 (w.q.m.) U.S.A. [Unresolved junior primary homonym of castanea Latreille, above.] Junior synonym of herculeanus: Mayr, 1863: 399.
 * atra. Formica atra Zetterstedt, 1838: 450 (m.) SWEDEN. Junior synonym of herculeanus: Nylander, 1846a: 894.
 * intermedia. Formica intermedia Zetterstedt, 1838: 448 (w.) SWEDEN. Junior synonym of herculeanus: Nylander, 1846a: 894.
 * whymperi. Camponotus herculeanus var. whymperi Forel, 1902i: 699 (w.q.) CANADA. Wheeler, W.M. 1910d: 330 (s.m.). Raised to species: Ruzsky, 1926: 108. Subspecies of herculeanus: Ruzsky, 1936: 90. Junior synonym of herculeanus: Creighton, 1950a: 367.
 * montanus. Camponotus herculeanus var. montanus Ruzsky, 1904a: 293 (w.) RUSSIA. Karavaiev, 1926e: 192 (s.w.q.). [Unresolved junior primary homonym of montanus Emery, above.] Subspecies of herculeanus: Ruzsky, 1926: 108. Junior synonym of herculeanus: Emery, 1925b: 72; Karavaiev, 1936: 178.
 * shitkowi. Camponotus herculeanus var. shitkowi Ruzsky, 1904a: 292 (w.q.) RUSSIA. Junior synonym of herculeanus: Emery, 1925b: 72; Karavaiev, 1936: 178; Arnol'di, 1967: 1819.
 * nadigi. Camponotus herculeanus var. nadigi Menozzi, 1922c: 142 (s.w.q.m.) ITALY. Material of the nomen nudum vagusherculeanus referred here by Emery, 1925b: 72; Kutter, 1977c: 205. Junior synonym of herculeanus: Yasumatsu & Brown, 1951: 30; Baroni Urbani, 1971c: 176.
 * eudokiae. Camponotus herculeanus var. eudokiae Ruzsky, 1926: 108 (w.) RUSSIA. Junior synonym of herculeanus: Radchenko, 1997a: 555.
 * caucasicus. Camponotus herculeanus subsp. caucasicus Arnol'di, 1967: 1822 (s.w.q.m.) CAUCASUS. Junior synonym of herculeanus: Arakelian, 1994: 85.
 * sachalinensis. Camponotus herculeanus var. sachalinensis Forel, 1904b: 38 (q.) MONGOLIA, RUSSIA.
 * Karavaiev, 1912b: 592 (m.).
 * Combination in C. (Camponotus): Emery, 1925b: 72.
 * As unavailable (infrasubspecific) name: Chapman & Capco, 1951: 221.
 * Junior synonym of saxatilis: Kuznetsov-Ugamsky, 1928b: 4; Kuznetsov-Ugamsky, 1929a: 18.
 * Status as species: Collingwood, 1981: 29; Bolton, 1995b: 121; Collingwood & Heatwole, 2000: 12; Imai, et al. 2003: 39.
 * Subspecies of herculeanus: Ruzsky, 1905b: 222; Wheeler, W.M. 1906c: 325; Yano, 1910: 422; Karavaiev, 1912b: 592; Ruzsky, 1926: 108; Arnol'di, 1967: 1821; Pisarski, 1969a: 230; Pisarski, 1969b: 304; Dlussky & Pisarski, 1970: 86; Collingwood, 1976: 306; Pisarski & Krzysztofiak, 1981: 159; Kupyanskaya, 1986b: 96; Kupyanskaya, 1990: 166; Morisita, et al. 1991: 41; Radchenko, 1994b: 116 (in key); Radchenko, 1996b: 1203 (in key); Radchenko, 1997a: 555; Radchenko, 2005b: 158.
 * Senior synonym of altaica: Arnol'di, 1967: 1821.
 * Senior synonym of jacuticus: Arnol'di, 1967: 1821.
 * Junior synonym of herculeanus: Yasumatsu & Brown, 1957: 49; Schar et al., 2018: 6.
 * altaica. Camponotus herculeanus subsp. altaica Ruzsky, 1926: 108 (w.) RUSSIA.
 * [First available use of Camponotus herculeanus saxatilis var. altaica Ruzsky, 1915b: 6; unavailable name.]
 * Subspecies of saxatilis: Ruzsky, 1936: 90.
 * Junior synonym of sachalinensis: Arnol'di, 1967: 1821.
 * Junior synonym of herculeanus: Schar et al., 2018: 6.
 * jacuticus. Camponotus (Camponotus) herculeanus var. jacuticus Karavaiev, 1929b: 210 (s.w.q.m.) RUSSIA.
 * Junior synonym of sachalinensis: Arnol'di, 1967: 1821.
 * Junior synonym of herculeanus: Yasumatsu & Brown, 1951: 30; Schar et al., 2018: 6.

Taxonomic Notes
Seifert (2019) found a low-level of hybridisation between C. herculeanus and Camponotus ligniperda. The frequency of hybridization between the two species is estimated for Central Europe as 0.2–1.0%. This low ratio indicates strong reproductive barriers considering syntopic occurrence at about 10% of the observation sites, a nearly complete overlap of swarming times and basically equal meteorological conditions to release swarming.

Schar et al. (2018): Camponotus sachalinensis Forel, 1904 syn. nov: This taxon has long been regarded a synonym of C. herculeanus (Collingwood, 1976; Kupyanskaya, 1990; Radchenko, 1996) but was raised to the rank of species (Bolton, 1995; Collingwood, 1981) without clear justification for this change in status. Our results support the hypothesis of synonymy with C. herculeanus. Camponotus herculeanus and C. sachalinensis form a young clade (~1.8 Ma, Figure 3) with a continuous distribution throughout the Holarctic. Camponotus sachalinensis represents the link between European and North American populations of C. herculeanus (Figures 2 and 3, Supporting Information Appendices S2 and S4). The current view of C. herculeanus occupying a disjunct distribution in the Western Palearctic and North America while being replaced by a distinct species, C. sachalinensis, in the Eastern Palearctic is bio-geographically not realistic. Camponotus sachalinensis is therefore here returned to synonymy with C. herculeanus. Its junior synonyms Camponotus herculeanus altaica Ruzsky, 1915 and Camponotus herculeanus jacuticus Karavaiev, 1929 are also placed in synonymy with C. herculeanus.

Worker
Wheeler (1910) for the synoymized variety whymperi: Major Length, 10--13 mm.; bead, 3.5 x 3.5 mm.; scape, 2.7 mm.; bind tibia, 3.3 mm.

Head; as broad as long, broader behind than in front, with broadly excised posterior border, rather convex sides and swollen cheeks. Eyes moderately large, flat. Mandibles 5-tootbed; convex at the base, flattened or slightly concave on their distal halves. Clypeus evenly convex, not carinate, its anterior border scarcely. produced, squarely truncated or feebly excised in the middle, with a deeper excision on each side near the cheeks. Frontal area large, subtriangular; frontal groove distinct. Frontal carinae lyrate, rather far apart. Antennal scapes rather short, not extending beyond the posterior corners of the bead, terete, neither dilated nor flattened at the base, incrassated distally. Thorax robust, rather high, feebly and evenly arcuate above, narrower than the bead, laterally compressed behind; epinotum obtusely angular, with subequal base and declivity, the former feebly convex, the latter feebly concave in profile. Petiole high, compressed anteroposteriorly, with convex anterior and nearly flat posterior surface, its border rounded, entire and ratber sharp. Gaster of the usual shape, legs moderately long and stout; middle and hind femora neither• compressed nor sulcate, elliptical in cross section.

Opaque; very densely and rather coarsely shagreened; mandibles, eyes, anterior portion, sides, lower surface and posterior corners of head more shining. Mandibles coarsely striato-punctate. Whole head covered with sparse, shallow punctures, which are larger, but not elongated, on the cheeks. Upper surface of thorax and gaster with scattered piligerous foveolae, the latter also with numerous small, often transverse punctures bearing tne pubescence.

Hairs brownish yellow, coarse, short and erect, not very abundant; absent on the cheeks and sides of bead. Antennal scapes .and legs covered with short slanting or appressed hairs. Pubescence very short, dilute, scarcely visible on the thorax, most distinct on the gaster but not concealing the sculpture.

Black; mandibles, anterior border of bead, antennae, legs, petiole, posterior portion of thorax and the base of the first gastric segment, deep red. Posterior borders of gastric segments dark brown. In some specimens, the posterior portions of the thorax, the mandibles, anterior portion of the head, the antennal scapes and femora are black. Middle and hind tibiae with only a few short bristles at the distal ends of their flexor surfaces.

Minor Length, 6-8 mm.

Head somewhat broader than long, but little broader behind than in front, with feebly convex sides and nearly straight posterior border. Eyes slightly convex, clypeus carinate. Antennal funiculus extending about one-third its length beyond the posterior corners of the head. In other respects like the worker major.

Queen
Wheeler (1910) for the synoymized variety whymperi: Length, 13-16 mm.

Very much-like the worker major. Head with somewhat straighter sides, but broader behind than in front. Eyes larger and more convex. Thorax through the wing-insertions scarcely broader than the head; epinotum with convex base, impressed in the middle; declivity longer and distinctly concave. Petiole more compressed than in the worker major, narrow and high, with rounded, entire and more acute border.

Surface throughout more shining than in the worker, especially the thorax, which is quite glabrous above; epinotum opaque, shagreened. Gaster very finely transversely shagreened and covered with small punctures. Mesonotum and gastric segments also with a few scattered piligerous foveolae.

Pilosity like that of the worker, but sparser and shorter. Pubescence also shorter and sparser, especially on the gaster.

Black; mandibles, legs, antennae and often also the epinotum, pleurae and petiole tinged with red. Wings very long (in large specimens 18 mm.), strongly tinged with brown; veins and stigma yellowish brown.

Male
Wheeler (1910) for the synoymized variety whymperi: Length, 9-10 mm.

Head through the eyes about as broad as long; broadly rounded behind; cheeks feebly convex, converging anteriorly, as long as the eyes. Ocelli very small. Mandibles edentate. Clypeus convex in the middle, but scarcely carinate, its anterior border broadly rounded and slightly sinuate in the middle. Thorax robust; epinotum with flattened and subequal base and declivity meeting to form a rounded obtuse angle. Petiole rather high, distinctly compressed anteroposteriorly, with thin, rather acute border, which is deeply excised in the middle above.

Opaque; very finely shagreened; gaster shining.

Hairs and pubescence shorter and sparser than in the worker, especially on the head and thorax. Cheeks without hairs. Short hairs on the legs and antennal scapes appressed and scarcely more than pubescence.

Black; mandibles, antennae and legs reddish. Wings paler than those of the female; veins and stigma yellow.