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Species: Camponotus (myrmothrix) atriceps   (Smith, 1858) 

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See Also:

Camponotus atriceps atricipitoesuriens, Camponotus atriceps nocens, Camponotus atriceps yankee

Taxonomic History (provided by Barry Bolton, 2014)

1 subspecies

Formica atriceps Smith, 1858a PDF: 44 (s.w.) BRAZIL. Neotropic. AntCat AntWiki

Taxonomic history

Mayr, 1862 PDF: 660 (q.); Forel, 1878c PDF: 76 (m.); Mariano, et al., 2001: 269 (k.).
Combination in Camponotus: Roger, 1862c PDF: 285.
Senior synonym of Camponotus taeniatus: Mayr, 1870a PDF: 378.
Oldest synonym of, and hence first available replacement name for, Formica abdominalis Fabricius, 1804 PDF: 409, designated by Bolton, 1995b: 86.
[Junior primary homonym of Formica abdominalis Latreille, 1802a: 175.].
Junior synonyms attached to Camponotus abdominalis Fabricius by Hashmi, 1973b: 82-83 are transferred to Camponotus atriceps, which hence is senior synonym of: Camponotus atricipitoesuriens, Camponotus costaricensis, Camponotus cupiens, Camponotus depressidens, Camponotus epistomatus, Camponotus esuriens (and its junior synonym Camponotus vulpinus), Camponotus fuchsae, Camponotus fulvacea, Camponotus fumata, Camponotus laevilata, Camponotus mediopallidus, Camponotus rabidus, Camponotus romani, Camponotus stercorarius, Camponotus taeniatus, Camponotus transvectus, Camponotus ustulatus.
Material of the unavailable names Camponotus defrictus, Camponotus flavobasalis, Camponotus luisae, Camponotus misionensis, Camponotus panamanus, referred to Camponotus abdominalis Fabricius by Hashmi, 1973b: 82, is here referred to Camponotus atriceps.
Current subspecies: nominal plus Camponotus atriceps nocens.
(status uncertain, see Hashmi, 1973b: 120).


Camponotus atriceps is a large reddish brown to black polymorphic ant with lighter coxae and legs, and rather abundant and distinctively flexuous anterior-projecting hairs on its mesosomal dorsum. The species thrives in synanthropic enviorments, and is considered a household pest (Campos-Farinha, 2005). Records of C. atriceps (and its dozens of junior synonyms) range across the Neotropics from southern South America up into Mexico. A specimen (JTL0000719) was collected by Jack Longino from Texas (Hidalgo Co.) on the Mexican border, and it is unknown whether the locality represents the northernmost extent of its natural range or an introduced population. It is possible that C. atriceps is a complex of closely related species rather than a single species, but more extensive taxonomic and phylogenetic studies will be required before the question is resolved.


Native Range. Throughout mainland Neotropics.
Introduced Range. Unknown, but possibly Texas. Records from Louisiana (Dash, 2004; Dash & Hooper-Bi, 2008; Dash et al., 2005) and Georgia (specimen FMNH-INS46082) are unconfirmed.

Costa Rica: throughout country below cloud forest elevations.


Specimens identified as C. atriceps are also reported from Louisiana (Dash, 2004; Dash & Hooper-Bi, 2008; Dash et al., 2005) and Georgia (specimen code FMNH-INS46082), both of which would likely be introduced populations. However, it is uncertain whether the species referred to in these studies is actually C. atriceps, as it is listed under the Tanaemyrmex subgenus rather than the traditionally applied Myrmothrix, and the diagnosis (attributed to an unidentified Mackay publication) is does not readily match most material of atriceps.

It is possible that the material referred to by Dash and colleagues belongs instead to C. floridanus Buckley. Both species had been considered junior synonyms of C. abdominalis (Hashmi, 1973) before Deyrup et al. (1988) raised C. floridanus to species status.Subsequently, C. abdominalis ( = Formica abdominalis Fabricius) was determined to be the junior homonym of Formica abdominalis Roger (Bolton, 1995). The decision to elevate C. floridanus to species status was supported by the biochemical evidence analyzed by Haak et al. (1996).

The natural history of Camponotus atriceps in Costa Rica has been richly chronicled by Jack Longino (see below), who reports it is extremely widespread in the country, preferring more disturbed habitats to mature forest understory. It is found nesting opportunistically in dead (and occasionally live) wood both arboreally and on the ground, and have been collected from canopy fogging of mature rainforest. The species is considered a house pest in Costa Rica and also in Brazil, where it is known for its damage to honeybee apiaries and its occurrence inside electronic appliances (Campos-Farinha, 2005). Brazilian populations are documented as being polygynous and polydomous (Campos-Farinha, 2005), but no such mention is given to the Costa Rica populations.

In Costa Rica (Jack Longino)
This "species" occurs throughout the American tropics and subtropics. In Costa Rica, atriceps is found almost anywhere in the country. It is common in second growth vegetation and other disturbed areas with high insolation, and it is relatively uncommon in mature forest understory. It is extremely varied and opportunistic in its nesting habits. I most often find nests in dead wood lodged in low vegetation or on the ground. They can be quite undiscerning: I once found a vigorous nest in an old shoe along a trashy roadside. I have found them nesting in dead wood deep inside mangrove swamps. They may nest in live branches of Cecropia trees on the rare occasions when Azteca does not occupy the branches, and they occasionally occur in internodes of Cecropia saplings. They occur in canopy fogging samples from mature rainforest, and in Corcovado I collected them nesting beneath epiphytes high in the canopy. The species is often a house pest, especially in the lowlands, and can be found nesting in wall spaces, infrequently used drawers, and old cardboard boxes.

Workers are typically nocturnal foragers. Similar to most Camponotus, workers are quite timid as isolated foragers. However, when nests are broken into, workers may come boiling out and bite the attacker. Very few Neotropical carpenter ants will aggressively defend a nest site. Other species that defend nests include C. sericeiventris, and in South America a close relative of atriceps, C. femoratus.

On multiple occasions I have observed parabiosis between C. atriceps and Azteca. Near the town of Tortuguero, on the Atlantic coast, I found an "archipelago" of antgardens on understory vegetation, overhanging a trail in the forest. The nests I could reach were relatively small and with only a few epiphyte seedlings, and appeared to be satellite or incipient nests at the edge of the large antgarden colony. The Azteca species was one I have not fully identified yet, but it is near ulei and may be gnava. The Azteca were out patrolling the surface of the nests and were very aggressive, but I discovered that the nests also contained C. atriceps. When the small nests were very severely disturbed (broken open with machete or by hand), C. atriceps workers would suddenly emerge. The smaller workers would flee, but major workers attacked me and bit my hands. One of the small nests was adjacent to a cluster of rotten sticks. The sticks were hollow and most contained adult males and alate queens of Azteca. However, one contained an aggregation of C. atriceps workers.

Another case of parabiosis occurred at Santa Rosa National Park. I was night collecting along the nature trail near the Casona. A fissure near the base of a live tree was an active nest entrance where abundant workers of Azteca (instabilis complex) were very active. In amongst them were occasional workers of C. atriceps, moving in and out of the same fissure and traveling among the Azteca workers with no apparent aggression.

A third case occurred near Puerto Viejo de Limon, in beach strand vegetation beneath coconut palms. A small shrub had an external carton nest of Azteca that was very active and vigorously defended. Just beneath and connected to it was a soft rotten stick that contained a C. atriceps nest. The Azteca workers were running freely in and out of the same stick, among the Camponotus workers, with no aggression.

I observed a fourth case at La Selva Biological Station. I discovered a cluster of carton nests of an Azteca velox-like species. The nests were scattered on the leaves and stems of a cluster of small melastome shrubs. One basal, central nest was built around a dead branch, about 50cm long. Camponotus atriceps were parabiotic in the central nest and some of the satellites. The Camponotus maintained galleries apart from the Azteca, but the Camponotus and Azteca chambers were interconnected and the two species appeared to move freely among each other. The carton construction was clearly associated with the Azteca chambers in the central branch, and not with the Camponotus chambers. The Azteca appeared to be the carton makers.

A fifth observation was also at La Selva. During night collecting I observed a fissure in the base of a tree, with carton construction covering part of the fissure. Camponotus and Azteca workers were both abundant and occurred together under the carton. The Azteca were in the velox group.

An open question is whether parabiosis in C. atriceps is a facultative behavior exhibited by a single panmictic population, with non-parabiotic cavity nesting being the more common alternative nesting behavior, or are the different nesting behaviors fixed species-level traits exhibited by distinct but cryptic species? Also, is this propensity for parabiosis in C. atriceps related to the apparently obligatory parabiosis in its relative, C. femoratus? Camponotus femoratus is famous for being a highly aggressive antgarden inhabitant in South America always found living parabiotically with Crematogaster carinata (= parabiotica). Are the parabiotic atriceps somehow an intermediate stage in the development of parabiosis, from which C. femoratus was derived?

Nest foundation appears to be by single claustral queens, because I find isolated dealate queens in cavities in dead wood and under epiphyte mats.

Nests are frequently home to inquiline cockroaches and silverfish.

The species is susceptible to fungal infection; Koos Boomsma collected a dead specimen with a sprouting Cordiceps fungus. The collection was from Panama.


Diagnosis among workers of introduced and commonly intercepted species in the United States. Worker caste polymorphic. Antenna 12-segmented. Antennal club indistinct. Antennal scape length less than 1.5x head length; with many hairs that are longer than the width of the scape. Eyes medium to large (greater than 5 facets). Head of worker lacking distinct ocelli. Antennal sockets and posterior clypeal margin separated by a distance equal to or greater than the minimum width of antennal  scape. Head length longer than head width. Dorsum of mesosoma lacking impression such that entire mesosomal dorsal profile forms an unbroken, convex curve. Promesonotum evenly convex, not separated from propodeum by metanotal groove. Propodeum and petiolar node both lacking a pair of short teeth. Propodeum lacking posteriorly projecting protrusion. Metapleuron lacking a distinct gland orifice. Waist 1-segmented. Petiole upright and not appearing flattened. Gaster armed with acidopore. Distinct constriction not visible between abdominal segments 3+4. Erect hairs dense on head, mesosoma and gaster; fine and flexuous, not long thick and produced in pairs.

Camponotus atriceps is diagnosed from other members of the genus introduced or commonly intercepted in the United States by the following characters: (1) metanotal groove not distinctly impressed (versus C. sexguttatus); (2) long erect hairs abundant on head, mesosoma and gaster (versus absent in C. rectangularis and C. variegatus); (3)erect hairs that are fine and flexuous (versus thick and stiff in C. planatus); (4) erect scape hairs longer than scape width (versus shorter in C. planatus); (5) gaster concolorous (versus variegated in C. variegatus).   


Bolton, B. (1995) A new general catalogue of the ants of the world. Harvard University Press, Cambridge, Mass., 504 pp.

Buckley, S.B. (1866) Descriptions of new species of North American Formicidae. Proc. Entomol. Soc. Phila., 6, 152-172.

Campos-Farinha, A.E.d.C. (2005) Urban pest ants of Brazil (Hymenoptera: Formicidae). In: Lee, C.Y. & Robinson, W.H. (Eds.) Proceedings of the 5th International Conference on Urban Pests, Suntec, Singapore, 10-13 July 2005. Perniagaan Ph'ng, Malaysia, pp. 81-84.

Dash, S.T. (2004) Species diversity and biogeography of ants (Hymenoptera: Formicidae) in Louisianna, with notes on their ecology. M.S. thesis, Louisiana State University. v + 290 p.

Dash, S.T., Hooper-Bui, L.M. & Seymour, M.A. (2005) The pest ants of Louisiana. A guide to their identification, biology, and control. Louisiana State University, Louisiana Agricultural Experiment Station, Louisiana Cooperative Extension Service, Pub. 2915.

Deyrup, M., Carlin, N., Trager, J. & Umphrey, G. (1988) A review of the ants of the Florida Keys. Florida Entomol., 71, 163-176.

Haak, U., Hlldobler, B., Bestmann, H.J. & Kern, F. (1996) Species-specificity in trail pheromones and Dufour's gland contents of Camponotus atriceps and C. floridanus (Hymenoptera: Formicidae). Chemoecology, 7, 85-93.

Hashmi, A.A. (1973) A revision of the Neotropical ant subgenus Myrmothrix of genus Camponotus (Hymenoptera: Formicidae). Stud. Entomol., 16, 1-140.

Smith, F. (1858) Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. British Museum, London, 216, 14 plates pp.

Taxon Page Author History

On 2012-06-05 21:48:46 Eli Sarnat modified References
On 2012-06-05 21:46:04 Eli Sarnat modified Biology
On 2012-06-05 21:45:21 Eli Sarnat modified Identification
On 2012-06-05 21:33:44 Eli Sarnat modified Biology
On 2012-06-05 21:32:10 Eli Sarnat modified Distribution
On 2012-06-05 21:24:59 Eli Sarnat modified Overview
On 2011-03-31 23:46:13 Eli Sarnat modified Distribution
On 2011-03-31 23:46:13 Eli Sarnat modified Biology
On 2011-03-31 23:46:13 Eli Sarnat modified References

Taxonomic Treatment (provided by Plazi)

Wild, A. L., 2007:
Caaguazú , Central (ALWC, IFML, INBP, LACM, MZSP). Literature records: Cordillera (Forel 1911b, Hashmi 1973).

Mayr, G., 1862:
[[ worker ]] Laenge 9 - 14 mm. Braeunlich gelb, wenig oder kaum glaenzend, der Kopf dunkelbraun, oefters braunroth, vorne heller, die Mandibeln braunroth, der Schaft schwarzbraun, die Geissel braungelb, die Knie, Schienen und Tarsen roethlich. Der ganze Koerper (auch der Schaft und die Beine, vorzueglich die Schienen) reichlich, lang, abstehend und licht fuchsroth behaart: die anliegende gelbe Pubescenz ist sehr spaerlich, am Hinterleibe reichlicher. Die Mandibeln sind glaenzend und zerstreut grob punctirt. Der Clypeus ist vorne wenig lappig vorgezogen und wenig beiderseits ausgerandet, die Mitte des Vorderrandes ist nach einwaerts gedrueckt und etwas ausgerandet; der Clypeus ist gekielt, so wie der Kopf fein lederartig gerunzelt und hie und da mit einem groben Puncte versehen. Der Thorax ist fein lederartig gerunzelt. Die Schuppe ist rundlich, vorne gewoelbt, hinten fast flach, oben gerundet und der Rand ziemlich dick. Der Hinterleib ist aeusserst fein und seicht quergestreift.
[[ worker ]] Laenge 12 - 14 mm. braeunlich gelb, der Kopf rothbraun, der Schaft schwarz, die Mandibeln roth, die Schenkel hell gelb, die Tarsen roethlich. Die dunklen Exemplare haben am Mesonotum drei rothbraune Laengsstreifen und die Endhaelfte des Hinterleibes oder fast den ganzen Hinterleib mehr oder weniger braun. Der Koerper ist aehnlich behaart wie beim [[ worker ]], doch ist die abstehende Behaarung, besonders am Schafte, Thorax und Hinterleibe eine sehr spaerliche, so wie auch die beiden letzteren ziemlich stark glaenzen. Die Form des Clypeus und die Skulptur des ganzen Kopfes ist ebenso wie beim [[ worker ]]. Der Thorax ¡ st fein lederartig gerunzelt, die stark glaenzende Scheibe des Mesonotum ist aber fast glatt. Die Schuppe ist groesser, breiter als beim [[ worker ]], und oben ausgerandet. Der Hinterleib glaenzt stark und ist nicht wie beim [[ worker ]] quergestreift, sondern aeusserst fein lederartig gerunzelt, welche Skulptur bei ungenauer Betrachtung fast wie punctirt aussieht. Die Fluegel sind gelblich, deren Rippen braeunlich gelb und ebenso das Randmal. Im Mus. Caes. Vienn. aus Brasilien, ebenso in meiner Sammlung.

Specimen Habitat Summary

Found most commonly in these habitats: 32 times found in lowland wet forest, 26 times found in tropical moist forest, 12 times found in Port of entry, 14 times found in 2º wet forest, 13 times found in tropical rainforest, 8 times found in lowland rainforest, 8 times found in 2º lowland tropical rainforest, 7 times found in mature wet forest, 8 times found in 2º lowland rainforest, 7 times found in montane wet forest, ...

Collected most commonly using these methods or in the following microhabitats: 71 times search, 39 times MiniWinkler, 34 times Baiting, 29 times Beating, 27 times Malaise, 10 times flight intercept trap, 6 times fogging, 6 times MaxiWinkler, 1 times under logs near camp, 2 times Blacklight, 2 times FIT, ...

Elevations: collected from 5 - 2160 meters, 458 meters average

Type specimens: Holotype of Camponotus atriceps: casent0903607; Holotype of Formica esuriens: casent0903608; syntype of Camponotus abdominalis costaricensis: casent0910333, casent0910334; syntype of Camponotus abdominalis cupiens: casent0910335, casent0910336; syntype of Camponotus abdominalis cupiens luisae: casent0911794; syntype of Camponotus abdominalis cupiens misionensis: casent0911795, casent0911796; syntype of Camponotus abdominalis depressidens: casent0911799, casent0911800; syntype of Camponotus abdominalis epistomatus: casent0911801; syntype of Camponotus abdominalis floridanus defrictus: casent0911797, casent0911798; syntype of Camponotus abdominalis floridanus panamanus: casent0911805; syntype of Camponotus abdominalis fuchsae: casent0910337, casent0910338; syntype of Camponotus abdominalis laevilata: casent0911802; syntype of Camponotus abdominalis mediopallidus: casent0910339, casent0910340; syntype of Camponotus abdominalis mediopallidus flavobasalis: casent0911803, casent0911804; syntype of Camponotus atriceps stercorarius: casent0910343; syntype of Camponotus atriceps ustulatus: casent0910341, casent0910342

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