Cephalotes complanatus

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Cephalotes complanatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. complanatus
Binomial name
Cephalotes complanatus
(Guérin-Méneville, 1844)

Cephalotes complanatus casent0909267 p 1 high.jpg

Cephalotes complanatus casent0909267 d 1 high.jpg

Specimen Labels


Nothing is known about the biology of Cephalotes complanatus.


A member of the basalis clade characterised, in the worker, by the following combination of characters: frontal carinae weakly upturned over the eyes and ending in a triangular angle, in the soldier, by the frontal carinae upturned before the eyes up to the vertexal angles, and, in the gyne, by the first gastral tergite with a pair of orange spots not covered by hairs. Workers of C. complanatus from Mato Grosso, Brazil differ from those of the other localities for the frontal carinae reduced to a thin margin over and behind the eyes and for the vertexal angles, obtuse. Small soldiers, in general, differ from the large ones by having the foveae denser and more impressed, and for the body more opaque. (de Andrade and Baroni Urbani 1999)

Keys including this Species


French Guiana, Suriname, Brazil, Peru, Bolivia and Colombia

Distribution based on Regional Taxon Lists

Neotropical Region: Bolivia, Brazil, Colombia, French Guiana (type locality), Peru, Suriname.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


The biology of many Cephalotes species is not known. Ants in this genus are common in the New World tropics and subtropics and are especially abundant and diverse in the canopies of Neotropical forests. The majority of species are arboreal. Species that live in other strata inhabit smaller trees, bushes or grass stems. These noon-arboreal species, due to their accessibility, are among the better studied members of the genus. There are also species that can be found in downed wood but it is likely the wood housed the colony before it fell to the ground. Soil nests are not known for any species nor do most species appear to extensively excavate plant tissue. They nest instead in preformed cavities. Overall, ants in the genus utilize a wide range of plants. Some species are predictable in their plant use but none appear to have evolved specialized mutualisms with particular plant species.

Worker castes typically include two forms, a worker and soldier, but there are a few species that are monomorphic. The larger soldier caste typically has an enlarged head disk. In some species the head of the soldier is very different from the worker while in others these differences are less pronounced. Queens and soldiers tend to share similar head morphology. Soldiers use their heads to plug the nest entrance. This can be very effective in excluding potential intruders. Other morphological differences between the worker castes are present but these differences have not been studied as well as head moprhology.

The behavioral repertoire of Cephalotes varians has been examined in great detail (ethograms from Wilson 1976, Cole 1980 and Cole 1983). Soldiers do little else besides defend the nest. This specialized soldier behavior is presumed to be the norm for most species. An especially interesting behavior occurs when workers are dislodged from trees: they "fly" towards the tree, often grabbing the trunk well above the ground (video).

Mature nest size varies, by species, from less than a hundred to many thousands of workers. Available evidence suggests most species are monogynous. Queens may mate with multiple males.

The proventriculus of the Cephalotes is peculiar relative to other ants. The morphology of the structure suggests it serves as a powerful pump and filter. This does not appear to lead these ants to have a highly specialized diet as most species appear to be general scavengers. Foragers have been observed feeding on carrion, bird feces, extrafloral nectaries and even tending membracids. Pollen feeding has been observed in some species, and this is somewhat specialized for ants, but it is not evident that any species restricts its diet to this resource in any significant way. Evidence for pollen feeding in Cephalotes has accumulated, in part, via finding digested pollen grains seen in infrabucal pellets. It has been suggested that the morphology of the proventriculus is a specialization for processing pollen.

More research examining all aspects of the biology of Cephalotes is needed. Our present understanding of these ants is largely based on species that live in locations other than the forest canopy, which is where Cephalotes are most common and diverse.



The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • complanatus. Cryptocerus complanatus Guérin-Méneville, 1844a: 424 (w.) FRENCH GUIANA. Mann, 1916: 451 (s.); De Andrade & Baroni Urbani, 1999: 257 (q.). Combination in Cryptocerus (Paracryptocerus): Emery, 1915i: 192; in Paracryptocerus: Kempf, 1951: 193; in Zacryptocerus: Brandão, 1991: 385; in Cephalotes: Baroni Urbani, 1998: 320. Senior synonym of angulatus: Emery, 1924d: 307; of amazonensis: Kempf, 1951: 193.
  • angulatus. Cryptocerus angulatus Smith, F. 1858b: 189 (w.) BRAZIL. Junior synonym of complanatus: Emery, 1924d: 307.
  • amazonensis. Cryptocerus multispinus var. amazonensis Forel, 1911e: 261 (w.) BRAZIL. Combination in Cryptocerus (Paracryptocerus): Emery, 1924d: 307. Junior synonym of complanatus: Kempf, 1951: 193.



Kempf (1951) - Length 6.9 mm. Median head length 1.68 mm; Weber's length of thorax 2,04 mm. Black; the following fuscous ferruginous: apex of mandibles, three apical tarsal segments. Tips of last funicular segment yellowish-brown.

Head subopaque, subquadrate. Mandibles finely reticulate-punctate, finely longitudinally rugulose. Sides of head very little sinuate, somewhat converging anteriorly, frontal carinae curved mesad, forming a blunt, small tooth in front of the eye, prolonged behind as a distinct carina, reaching the occipital corner, very scarcely upturned above the eye. Occipital corner forming a distinct angle. Occipital border emarginate mesally, sharply crested laterad. Upper surface of head very little convex, finely reticulate-punctate, more sparsely covered with shallow, oval grooves, each containing a conspicuous, usually canaliculate, silvery, appressed scale. Cheeks strongly carinate below, densely covered with large, canaliculate, silvery scales. Lower surface of head more fulgid, with sparser scales.

Thorax subopaque. Sides of lateral pronotal plates somewhat converging behind, anterior corner angulate, posterior corner rounded. Promesonotal suture obsolete. Mesonotum with a strong lateral spine. Mesoepinotal suture vestigial. Basal face of epinotum with a large, broad triangular, plate-like tooth on each side and a posterior rather short, slender, acuminate spine, projecting obliquely backward, much shorter than the length of the basal face. Promesonotum, in profile, somewhat convex. Posterior border of basal face of epinotum submarginate. Sides of declivous face carinate. Dorsum of thorax finely reticulate-punctate, with sparse, squamiferous foveolae, the scales being appressed and canaliculate. Laterotergite of pronotum longitudinally striated. Declivous face very finely, superficially reticulate. Tibiae prismatic.

Petiole and postpetiole subopaque, with a vestigial longitudinal medial carinule above, beginning behind the anterior border on the postpetiole. Spines of petiole upturned and slightly recurved.

Gaster subopaque, elongate, cordiform, shallowly emarginate anteriorly mesad; with an anterolateral foliaceous border. Sculpture as on dorsum of thorax, foveolae only vestigial, scales slender, simple. Erect hair confined to the terminal tergites and the sternites.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 4.44-7.88; HL 1.12-1.92; HW 1.36-2.28; EL 0.38-0.53; PW 1.28-2.16; PeW 0.88-1.60; PpW 0.80-1.36; HBaL 0.45-0.76; HBaW 0.19-0.32; CI 121.4-135.0; PI 105.5-114.9; PPeI 130.0-146.8; PPpI 139.1-160.0; HBaI 40.0-42.2.


de Andrade and Baroni Urbani (1999) - Head strongly convex, without disc. Frontal carinae broad anteriorly, slightly converging and upturned before the beginning of the eyes and ending in the vertexal angles. Vertexal angles obtuse. Vertex with a pair of median, small denticles connected each other by a faint carina. Mandibles with a thick, lateral carina.

Mesosoma. Humeral angles with a broad lateral lamella, its anterior border making a straight angle with the sides and converging posteriorly. Pronotal carina thick, strongly marked and broadly interrupted in the middle by a superficial notch. Promesonotal and propodeal sutures impressed. Mesonotum with a broad, round, protruding tooth. Propodeum clearly differentiated in basal and declivous faces. Basal face narrow anteriorly, strongly diverging posteriorly to a pair of broad, round expansions and followed by a pair of subround teeth.

Petiole with distinctly differentiated anterior and posterior faces. Anterior face truncate and separated from the posterior one by a superficial carina; posterior face sloping backwards. Petiolar spines as long as the petiolar length; their base almost as broad as the sides of the petiole, curved back- and upwards. Postpetiole with anterior and posterior faces; anterior face truncate, high and separate from the posterior one by a carina shortly interrupted in the middle. Postpetiolar spines arising from the anterior face of the postpetiole, ending on the middle of the postpetiolar sides, thick and directed laterally.

Gaster oval, with a broad lamella reaching the stigma posteriorly.

Legs. Fore coxae tumuliform anteriorly. Fore femora broad, not angulate. Outer face of the mid and hind femora with a pair of denticles on the middle. Mid and hind basitarsi flat; their base twice broader than the apex.

Sculpture. Head minutely and superficially reticulate-punctate, covered by faint, small, foveae smaller than their interspaces. Mesosoma with the same type of sculpture as the head dorsum, but with larger and denser foveae on the sides of the pronotum, on the propodeum and on the propleurae. Pedicel, lower meso- and metapleurae, distal part of the outer face of the femora, outer face of the tibiae and anterolateral third of the first gastral tergite with dense, oval foveae. Declivous face of the propodeum, upper part of the meso- and metapleurae, anterior face of the pedicel, legs, and first gastral sternite reticulate-punctate, almost shining, with minute, superficial foveae on the sternite. Remaining part of the first gastral tergite superficially reticulate-punctate and with small, superficial foveae.

Pilosity. Each fovea bears a thick, appressed, hair of thickness proportional to the size of the fovea. Legs with rare, appressed, short and thin hairs. Border of the gastral segments with long, slightly clavate hairs; similar hairs but more clavate on the legs. Border of the sternites with rare, long, pointed hairs.

Colour. Black almost shining. Tip of the last funicular joints orange.

Measurements (in mm) and indices: TL 9.04-1 0.04; HL 2.32-2.60; HW 2.76-2.96; EL 0.56-0.64; PW 2.60-2.88; PeW 1 .60-1.92; PpW 1 .40-1 .72; HBaL 0.80-0.84; HBaW 0.32-0.36; CI 113.8-119.0; PI 102.4-106.1; PPeI 150.0-162.51; PPpI 167.4-185.7; HBaI 40.0-45.0.


de Andrade and Baroni Urbani (1999) - Head as in the soldier, but less convex, with the frontal carinae less broad and less upturned over the eyes. Vertexal angles more pointed. Ocelli far from the vertexal margin.

Mesosoma gently convex in profile. Pronotal sides angulate only. Pronotal carina superficially marked on the sides. Mesonotum flat in side view. Lower mesopleurae with a lateral tooth. Sides of the basal face of the propodeum with two pairs of teeth, the first pair broad and subtriangular, the second pair with parallel, not diverging, external sides, longer and more pointed than the first one. Declivous face of the propodeum with posteriorly converging sides.

Petiole with distinctly differentiate anterior and posterior faces; anterior face oblique truncate; posterior face sloping backwards. Petiolar sides with pointed, lateral spines slightly directed up- and backwards. Postpetiole convex; its anterior face higher than the petiolar dorsum; posterior face of the postpetiole not clearly separate from the anterior one by a "V" shaped carina; postpetiolar spines broad, short, pointed and directed laterally.

Gaster anterolaterally with protruding lobes and with a margin not reaching the stigma backwards.

Legs. As in the soldier.

Sculpture. Head minutely and superficially punctate, covered by superficial, small, variably clumped foveae. Ventral face of the head superficially with large, sparse foveae. Mesosoma with the same type of sculpture as the head dorsum, but with larger and denser foveae on the sides of the pronotum, on the propodeum, on the propleurae and on the lower mesopleurae. Posterior face of the petiole and of the postpetiole with dense, oval foveae; similar sculpture but with foveae smaller on the distal part of the outer face of the femora and on the outer face of the tibiae. Upper mesopleurae with dense, small foveae. Declivous face of the propodeum, anterior face of the pedicel, upper metapleurae, first sternite and femora minutely and superficially reticulate-punctate, almost shining; this same type of sculpture but more impressed and opaque on the lower metapleurae and on the remaining parts of the legs. First gastral tergite minutely and superficially punctate and shining.

Pilosity. Each fovea bears a thick, appressed, hair of thickness proportional to the size of the fovea. Legs and gaster with appressed, short, thin hairs, denser on the gaster. Border of the gastral segments with long, slightly clavate hairs; similar hairs but shorter on the first sternite. Legs with short, sparse, clavate hairs. Border of the sternites with rare, long, pointed hairs.

Colour. Black shining. First gastral tergite with a pair of orange spots on the anterolateral third.

Measurements (in mm) and indices: TL 11.84-12.48; HL 2.48-2.52; HW 2.78-2.80; EL 0.56-0.60; PW 2.64-2.68; PeW 1.36-1.52; PpW 1.48-1.64; HBaL 0.90-0.96; HBaW 0.37-0.38; CI 110.3-112.9; PI 104.5-105.3; PPeI 176.3-194.1; PPpI 163.4-178.4; HBaI 39.6-42.1.

Type Material

de Andrade and Baroni Urbani (1999):

Worker. Type locality: Cayenne, French Guyana. Type material presumably lost, not in the Zoologische Staatssammlung, Munich. A specimen (but not a type) labelled complanatus from Magdalena, Colombia in the Guerin collection at the ZSMC is actually C. femoralis.

Cryptocerus angulatus. Soldier. Type locality: Tunantins (Brazil). Type material: soldier in the Museum of the Department of Entomology, University of Oxford (Kempf: 1959: 97), not available for the present study, and a soldier labelled "Tunantins" and "57 125" in the The Natural History Museum, examined.

Cryptocerus multipinus var. amazonensis. Worker. Type locality: Amazon. Type material: two syntype workers labelled "Amazonas, H. W. Bates S.", one in Musee d'Histoire Naturelle Genève and one in ZSMC, examined.


  • Baroni Urbani, C. 1998b. The number of castes in ants, where major is smaller than minor and queens wear the shield of the soldiers. Insectes Soc. 45: 315-333 (page 320, Combination in Cephalotes)
  • Brandão, C. R. F. 1991. Adendos ao catálogo abreviado das formigas da região Neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412 (page 385, Combination in Zacryptocerus)
  • de Andrade, M. L.; Baroni Urbani, C. 1999. Diversity and adaptation in the ant genus Cephalotes, past and present. Stuttgarter Beitrage zur Naturkunde Series B (Geolgie and Palaontologie). 271:1-889. (page 257, queen described)
  • Emery, C. 1915g. Noms de sous-genres et de genres proposés pour la sous-famille des Myrmicinae. Modifications à la classification de ce groupe (Hymenoptera Formicidae). Bull. Soc. Entomol. Fr. 1915: 189-192 (page 192, Combination in Cryptocerus (Paracryptocerus))
  • Emery, C. 1924f [1922]. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [concl.]. Genera Insectorum 174C: 207-397 (page 307, Senior synonym of angulatus)
  • Guérin-Méneville, F. E. 1844a. Iconographie du règne animal de G. Cuvier, ou représentation d'après nature de l'une des espèces les plus remarquables, et souvent non encore figurées, de chaque genre d'animaux. Insectes. Paris: J. B. Baillière, 576 pp. (page 424, worker described)
  • Kempf, W. W. 1951. A taxonomic study on the ant tribe Cephalotini (Hymenoptera: Formicidae). Rev. Entomol. (Rio J.) 22: 1-244 (page 193, Senior synonym of amazonensis)
  • Mann, W. M. 1916. The Stanford Expedition to Brazil, 1911, John C. Branner, Director. The ants of Brazil. Bull. Mus. Comp. Zool. 60: 399-490 (page 451, soldier described)

References based on Global Ant Biodiversity Informatics

  • Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
  • Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
  • Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
  • Kempf W. W. 1951. A taxonomic study on the ant tribe Cephalotini (Hymenoptera: Formicidae). Revista de Entomologia (Rio de Janeiro) 22:1-244
  • Kempf W. W. 1959. Sôbre algumas formigas Cephalotini do Museu de Oxford (Hymenoptera, Formicidae). Revista Brasileira de Biologia 19: 91-98.
  • Kempf W. W. 1964. Additions to the knowledge of the Cephalotini ants (Hymenoptera, Formicidae). Papeis Avulsos de Zoologia (São Paulo) 16: 243-255.
  • Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
  • Kusnezov N. 1953. La fauna mirmecológica de Bolivia. Folia Universitaria. Cochabamba 6: 211-229.
  • Maes, J.-M. and W.P. MacKay. 1993. Catalogo de las hormigas (Hymenoptera: Formicidae) de Nicaragua. Revista Nicaraguense de Entomologia 23.
  • Mann W. M. 1922. Ants from Honduras and Guatemala. Proceedings of the United States National Museum 61: 1-54.
  • Radoszkowsky O. 1884. Fourmis de Cayenne Française. Trudy Russkago Entomologicheskago Obshchestva 18: 30-39.
  • da Silva de Oliveira A. B., and F. A. Schmidt. 2019. Ant assemblages of Brazil nut trees Bertholletia excelsa in forest and pasture habitats in the Southwestern Brazilian Amazon. Biodiversity and Conservation 28(2): 329-344.
  • de Andrade, M.L. & C. Baroni Urbani. 1999. Diversity and Adaptation in the ant genus Cephalotes, past and present. Stuttgarter Beitrage zur Naturkunde Serie B 271. 893 pages, Stuttgart