Cephalotes inaequalis

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Cephalotes inaequalis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. inaequalis
Binomial name
Cephalotes inaequalis
(Mann, 1916)

Cephalotes inaequalis P casent0627946.jpg

Cephalotes inaequalis D casent0627946.jpg

Specimen Label

Besides knowing some specimens have been collected from scrub forest, little is known about the biology of Cephalotes inaequalis.

Identification

A member of the laminatus clade differing from its sister species Cephalotes laminatus, in the worker, by the head shorter and broader and by the pronotal and propodeal spines shorter and thicker, and, in the soldier, by the head broader, with parallel frontal carinae less converging anteriorly, and by the sculpture more superficial and opaque, and, in the gyne, by the head, flatter and broader. C. inaequalis and laminatus are sympatric in many areas on NW of Brazil. The separation of the two species has been facilitated by the examination of workers associated with soldiers. Cephalotes christopherseni (q. v.) belongs to the same subclade as Cephalotes inaequalis but is much closer to Cephalotes spinosus. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Brazil, Colombia and Guyana.

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality), Colombia.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

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.

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • inaequalis. Cryptocerus (Cryptocerus) inaequalis Mann, 1916: 449 (w.) BRAZIL. De Andrade & Baroni Urbani, 1999: 228 (s.q.). Combination in Cryptocerus (Paracryptocerus): Emery, 1924d: 307; in Paracryptocerus: Kempf, 1951: 163; in Zacryptocerus: Brandão, 1991: 386; in Cephalotes: De Andrade & Baroni Urbani, 1999: 227.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Kempf (1951) - Length 5.5 mm. Median head length 1.29 mm; Weber's length of thorax 1 .63 mm. Black; the following pale yellowish-brown and semitranslucid: frontal carinae, occipital lamellae, thoracic and peduncular spines; lamellate border of the first gastral tergite. Ferruginous: tibiae, tarsi, apices of mandibles. Fuscous: femora and base of mid and hind basitarsi.

Head subopaque; broader than long, broadest behind the eyes, narrowed in front; interocular distance longer than maximum length of head (78:74). Posterior margin between the lobes, scarcely concave, almost straight, the occipital angles with prominently projecting, obliquely truncate lamellae, the apical border of which is distinctly sinuate. Cheeks strongly marginate beneath, covered with dense, large, canaliculate, golden scales. Integument very finely reticulate-punctate, sparsely covered with slender, simple, short, appressed, scale-like hairs which, near the occipital border, are situated in grooves.

Thorax subopaque. Pronotum angulate at the shoulders; broadly expanded behind the shoulders with two broad, flat, triangular teeth on each side; posterior corners of pronotum more or less rounded and projecting. Promesonotal suture obsolete. Mesonotum with a small, acute, lateral tooth. Mesoepinotal suture impressed. Basal face of epinotum with two large, broad, flat, triangular teeth on each side, the anterior tooth sligtly smaller than the posterior. The posterior border of the second tooth forms a sharp crest and delimits the distinctly excavated declivous face laterad. Sculpture as on head, but sparsely foveolate above, with very short, broad scales, some of which arc distinctly canaliculate, becoming slightly longer on the basal face of the epinotum. Laterotergite of pronotum and mesopleura longi tudinally striated. Excavated portion of declivous face without distinct macrosculpture and without scales.

Petiole subopaque, transverse, with set off, slender, long, lateral spines, arising from the anterior corner, gently curved backwrds, rounded at apex. Postpetiole with somewhat shorter, broader lateral spines, bluntly rounded at apex, curving obliquely foreward. Sculpture as on thorax, less distinctly foveolate, scales slightly longer.

Gaster subopaque; broadly cordiform, very convex above. First gastral tergite with anterolateral, flat, lamellate border, almost as broad as the length of petiole. Tergites and sternites finely, densely and rather sharply reticulate-punctate. Scales of gaster sparser, simple, short, not situated in distinct foveolae. Erect pile limited to the 2nd - 4th gastral tergites and the sternites.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 4.89-5.68; HL 1.20-1.42; HW 1.64-2.04; EL 0.38-0.44; PW 1.28-1.52; PeW 0.66-0.86; PpW 0.55-0.74; HBaL 0.51-0.60; HBaW 0.12-0.13; CI 135.5-143.7; PI 123.5-134.2; PPeI 176.7-200.0; PPpI 205.4-232.7; HBaI 21.7-25.0.

Soldier

de Andrade and Baroni Urbani (1999) - Head subquadrate, convex dorsally. Frontal carinae anteriorly gently converging, straight laterally and terminating behind the eyes. Vertexal angles round or obtuse. Vertex with a pair of median small, stout teeth. Mandibles broad, short and without lateral angle.

Mesosoma. Scapular angles visible. Pronotal sides anteriorly with a pair of broad, bidentate lamellae; first pair of lamellar teeth pointed and the second one round or truncate; pronotal sides converging posteriorly. Pronotal carina marked, interrupted in the middle by a notch. Promesonotal suture impressed. Mesonotal sides with a pair of broad, truncate teeth. Propodeal suture impressed. Propodeum with clearly differentiate basal and declivous faces. Basal face plate-like, its sides diverging posteriorly and with a pair of triangular teeth followed by a pair of spines; propodeal spines diverging backwards, with the base continuing into the anterior half of the declivous face. Declivous face of the propodeum converging posteriorly.

Petiole with the anterior face obliquely truncate. Petiolar sides with a pair of thick spines arising anteriorly and curved backwards. Postpetiole slightly narrower than the petiole and convex dorsally. Postpetiolar spines originating from the anterior face, slightly directed forwards and with almost round tips.

Gaster oval, with a pair of broad lamellae reaching at least the stigma posteriorly.

Legs. Fore coxae tumuliform anteriorly. Mid and hind femora without angles or denticles. Mid and hind basitarsi not flat and with parallel sides.

Sculpture. Head dorsum minutely and superficially punctate, subopaque and covered by faint, small foveae smaller than their interspaces. Frontal carinae superficially shining and with foveae sparser than those on the remaining head dorsum. Ventral part of the head posteriorly shining and with deeper and larger foveae than on the head dorsum, and anteriorly punctate and with foveae denser and smaller than on the posterior half. Pronotum and mesonotum minutcly and superficially punctate, slightly shining and with foveae larger and deeper than those on the on the head dorsum. Basal face of the propodeum and anterior third of the declivous face punctate and densely foveolate, the foveae deeper than on the other mesosomal parts. Proplcurae punctate and with large, variably clumped, foveae. Meso- and metapleurae punctate and with rare, superficial foveae. Pedicel punctate and with dense, irregular foveae, shallower than those on the basal face of the propodeum. Declivous face of the propodeum, gaster legs and reticulate-punctate, the reticulation broader and more superficial on the legs. Outer face of the femora with irregular, thin rugosities between superficial, irregular foveae. First gastral tergite with superficial foveae diminishing in size and shallower posteriorly. Anterior and posterior faces of the femora, and centre of the first gastral sternite shining. Some specimens shining on the first gastral tergite as well. Posterior half of the first gastral sternite centrally superficially reticulate-punctate, almost shining.

Pilosity. Each fovea bears an appressed hair. Gastral sternites and legs with thin, appressed hairs. Posterior border of the gastral tergites and of the sternites, and legs with clubbed hairs. Sternites with additional rare, pointed, long hairs.

Colour. Black. Frontal carinae anteriorly with a ferruginous, semitransparent spot. Lamellaceous border of the gaster yellow ferrugineous and semitransparent. Gaster with or without a small pair of orange spots anteriorly. Tibiae and tarsomeres orange to dark ferrugineous.

Measurements (in mm) and indices: TL 7.08-7.98; HL 1.80-2.12; HW 2.40-2.64; EL 0.48-0.54; PW 2.00-2.16; PeW 0.78-0.93; PpW 0.80-0.85; HBaL 0.59-0.65; HBaW 0.16-0.17; CI 123.5-135.0; PI 116.7-122.2; PPeI 229.8-246.1; PPpI 234.1-254.1; HBaI 24.0-27.4.

Queen

de Andrade and Baroni Urbani (1999) - Head broader than long, more convex than in the soldier. Frontal carinae gently converging anteriorly; their sides parallel and ending behind the eyes. Vertexal angles obtuse and reaching the ventral border of the eyes anteriorly. Vertex with a pair of median, small teeth connected each other by a weak median carina. Clypeus anteriorly concave, with a pair of small lateral teeth. Eyes gently convex. Mandibles as in the soldier.

Mesosoma. Scapular angles short but visible. Humeral angles with a pair of pointed anterior teeth. Pronotal sides straight. Pronotal carina narrow, superficially marked and interrupted in the middle. Mesonotum and scutellum flat. Lower mesopleurae with a small denticle. Basal face of the propodeum anteriorly with a pair of minute denticles and with a pair of pointed teeth. Declivous face with the sides converging posteriorly.

Petiole as in the soldier. Postpetiole as in the soldier but with thicker and slightly truncate spines.

Gaster with a pair of broad, strongly marginate anterior lobes.

Legs. As in the soldier.

Sculpture. As in the soldier but differing in the following: ventral part of the head punctate and with deep and dense foveae. Posterior part of the mesonotum and scutellum with dense foveae separated by longitudinal interspaces. Propleurae with denser and deeper foveae. Upper metapleurae with dense, small foveae. Lower mesopleurae and upper metapleurae with variably clumped foveae. Lower metapleurae with thin, longitudinal rugosities on the ventral part, the rest punctate. First gastral tergite superficially reticulate on the anterior third, the rest superficially punctate and shining. Remaining tergites and sternites reticulate. Centre of the first gastral sternite shining. Foveae on the gaster more impressed.

Pilosity. As in the soldier but with the clubbed hairs sparse and present also on the mesosoma, on the pedicel, and on the gaster.

Colour. Black. Frontal carinae with two pairs of ferruginous and semitransparent spots. Gaster with two pairs of orange spots, the first pair on the anterior third and the second ones before the posterior border of the first tergite. Tibiae and tarsomeres orange to dark ferruginous.

Measurements (in mm) and indices: TL 12.18; HL 2.48; HW 3.02; EL 0.56; PW 2.78; PeW 1.16; PpW 1.54; HBaL 0.80; HBaW 0.23; CI 121.8; PI 108.6; PPeI 239.6; PPpI 180.5; HBaI 28.7.

Type Material

de Andrade and Baroni Urbani (1999) - Worker. Type locality: Abuna (Rondonia, Brazil). Type material one worker (syntype) labelled: "Rio Madeira, Abuna, Brazil, Mann & Baker", in Museum of Comparative Zoology, examined.

References

  • Brandão, C. R. F. 1991. Adendos ao catálogo abreviado das formigas da região Neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412 (page 386, Combination in Zacryptocerus)
  • de Andrade, M. L. and 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 228, soldier, queen described;page 227, Combination in Cephalotes)
  • Emery, C. 1924f [1922]. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [concl.]. Genera Insectorum 174C: 207-397 (page 307, Combination in Cryptocerus (Paracryptocerus))
  • Kempf, W. W. 1951. A taxonomic study on the ant tribe Cephalotini (Hymenoptera: Formicidae). Rev. Entomol. (Rio J.) 22: 1-244 (page 163, Combination in Paracryptocerus)
  • 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 449, worker described)