Cephalotes marginatus

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Cephalotes marginatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. marginatus
Binomial name
Cephalotes marginatus
(Fabricius, 1804)

Cephalotes marginatus casent0912581 p 1 high.jpg

Cephalotes marginatus casent0912581 d 1 high.jpg

Specimen Labels

Synonyms

Nothing is known about the biology of Cephalotes marginatus.

Identification

A member of the atratus clade exhibiting, in the worker and gyne, the following characters separating it from the sister species Cephalotes atratus: abundant suberect pilosity on the ventral face of the gaster and - in the workers – median pronotal spines ca. 1/4 of the size of the external ones instead of simply minute or absent as in atratus. The males of the two species differ in the CI values as given under the respective descriptions. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil, Colombia, Ecuador, French Guiana, Guyana (type locality), Suriname.

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.

  • marginatus. Cryptocerus marginatus Fabricius, 1804: 419 (q.) GUYANA. De Andrade & Baroni Urbani, 1999: 124 (m.). Combination in Cephalotes: De Andrade & Baroni Urbani, 1999: 124. Junior synonym of atratus: Klug, 1824: 200; Roger, 1862c: 291. Revived from synonymy and senior synonym of decemspinosus (and its junior synonym spissus): De Andrade & Baroni Urbani, 1999: 124.
  • decemspinosus. Cephalotes decemspinosus Santschi, 1920f: 148 (w.) FRENCH GUIANA. Senior synonym of spissus: Kempf, 1951: 125. Junior synonym of marginatus: De Andrade & Baroni Urbani, 1999: 124.
  • spissus. Cephalotes decemspinosus var. spissus Santschi, 1929d: 302 (w.) SURINAM. Junior synonym of decemspinosus: Kempf, 1951: 125.

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

Description

Worker

de Andrade and Baroni Urbani (1999) - Moderately variable in size. Head with the sides (frontal carinae) subparallel, very weakly crenulate only on the anterior fourth and upturned laterally. Vertexal border continuing the frontal carinae and sloping ventrally, bearing two pairs of lateral spines, the distal pair ca. 1/2 longer than the proximal one, very weakly carinate to straight posteriorly. Eyes ca. at 6/7 of head length posteriorly and protruding from the ventral border of the antennal scrobes.

Mesosoma relatively slender. Pronotum making an angle of ca. 90° with the mesonotum, straight and inclined antero-ventrally at about 45° on the longitudinal body axis. Posterior pronotal third with two pairs of spines, the external pair almost continuing laterally the pronotal surface and long as half of the maximum head width; the median pair, perpendicular to the pronotum, is regularly much longer than in atratus, ca. 1/4 as long as the external pair. Promesonotal suture well marked. Mesonotum straight and flat in profile. Propodeal suture deeply impressed. Propodeum with basal and declivous faces subequal in length and forming an angle of ca. 90°. Basal face practically flat, passing into the sides with a round angle. Declivous face very weakly concave. Propodeal spines only slightly shorter than the external pronotal ones, obliquely pointing backwards. Metapleural-propodeal suture oblique and deeply impressed laterally.

Petiole with slightly concave anterior and slightly convex posterior faces, bearing two small, dorso-lateral denticles. Postpetiole subequal to petiole in width, narrower posteriorly, with a very short, perpendicular anterior face and nearly flat dorsal one; the angle between the anterior and superior faces bears a pair of short spines, slightly longer than the petiolar ones and directed upwards; ventrally, another pair of spines obliquely directed forwards, subequal to the dorsal ones in length but thinner.

Gaster elongate, incised at the articulation with the postpetiole and marginate anteriorly.

Mid and hind tibiae strongly compressed laterally anq with marginate external borders.

Pilosity and sculpture. Whole body, except the spines and the appendages covered by dense, superficial, oval pits. The pits on the head, mesosoma and pedicel bear a thick, truncate hair and can be interpreted as sensilla auricillica. The pits on the gaster are more superficial, each pit bearing simply pointed hairs (in atratus the deeper pits are generally limited to the head and pronotum). A few suberect, thick bristles on the anterior pair of vertexal spines, on both pairs of pronotal spines and on the pedicel. Numerous yellowish standing hairs on the posterior border of all gastral segments and at least on the distal half of the first gastral sternite. Legs with few, yellowish, subdecumbent or decumbent hairs, particularly on the coxae and on the tibiae.

Colour black moderately shining except the frontal carinae, ferrugineous.

Measurements (in mm) and indices: TL 9.60-17.00; HL 2.04-3.50; HW 2.60-5.20; EL 0.53-0.80; PW 2.60-5.00; PeW 0.68-1.08; PpW 0.75-1.28; HBaL 1.60-2.48; HBaW 0.38-0.60; CI 127.1-148.6; PI 88.2-110.6; PPeI 382.3-555.5; PPpI 346.7-510.2; HBaI 23.6-24.8.

Queen

de Andrade and Baroni Urbani (1999) - Head slightly wider than long, with the sides converging anteriorly and weakly crenulate only on their anterior fifth. Clypeus broadly concave. Vertexal border weakly concave, nearly straight. Abroad median dorsal depression of the head capsule at about 2/3 of its length. Frontal line reaching the median depression or continuing through it up to the median ocellus. Two pairs of lateral vertical spines subequal in size and disposed perpendicularly to the vertexal angles; a third pair of smaller, blunt, vertexal spines behind and between the pair ocelli. Eyes, in dorsal view, not covered by the frontal carinae. Ocelli deeply impressed and subequal in distance each one to the other two. Mandibles robust, serially toothed and transversely impressed at mid length. Antennal scape thick; funicular joints gradually increasing in size from the second to the last.

Mesosoma, in dorsal view, remarkably broadened at the height of the mesopleurae, with flat mesonotum and scutellum, both higher than the pronotum and propodeum in profile. Humeral spines developed and pointing perpendicularly to the major body axis, followed by a pair of minute denticles caudally. Medial pronotal spines much broader and shorter, obtuse to pointed. Propodeum with basal face gently sloping backwards, shorter than the declivous face, which is nearly straight. Propodeal spines robust, their dorsal surface complanary with the basal face of the propodeum, long 1/2 of their distance at the apex, diverging caudally.

Petiole sessile, slightly lower than the postpetiole, with anterior face flat and posterior face only slightly shorter than the anterior one, bearing only two weak dorsal protuberances and no spines. Postpetiole slightly broader than petiole, twice broader than long, bearing two more prominent dorsal protuberances and a broad ventral lamella.

Gaster incised at the articulation with the postpetiole, not marginate; in dorsal view only the first and part of the second tergites visible.

Legs with mid and hind tibiae compressed laterally and distally marginate on the external face.

Fore wings infuscate with very dark R+ Sc connected with a marked pterostigma. Rsf5 connected with R1. R1 almost reaching or entirely reaching and outlining the wing border. A, Cu-A, Cu-A1 and Mf4 well marked and nearly reaching the wing border. Hind wings with well marked R, M+CuA, 1A, CuA, r-m and M. Distal parts of 1A, CuA and M obsolete and nearly reaching the wing border.

Sculpture and pilosity as in the worker but more uniform over the whole body, with the pits more deeply impressed on the pedicel. Abundant, short, truncate, yellowish hairs on the terminal parts of the gastral segments and at least on the distal half of the first gastral sternite.

Colour uniformly black, more shining on the gaster, with a ferrugineous strip parallel to the frontal carinae where the integument is thinner and semi-transparent.

Measurements (in mm) and indices: TL 19.60-20.30; HL 3.28-3.70; HW 4.35-4.90; EL 0.83-0.88; PW 4.60-4.90; PeW 1.44-1.72; PpW 1.60-1.64; HBaL 2.00-2.20; HBaW 0.60-0.61; CI 127.0-132.6; PI 89.8-97.9; PPeI 315.8-331.1 ; PPpI 287.5-306.2; HBaI 27.3-30.5.

Male

de Andrade and Baroni Urbani (1999) - Head much broader than long, with the cheeks strongly converging anteriorly. Vertexal margin prolonging backwards into a neck. Vertexal angles diverging towards the posterior border of the eyes, with a median pair of obtuse, triangular denticles sometimes connected through a carina to the external pair denticles close to the eyes. Frontal carinae more or less raised over the head dorsum. Frontal line marked and reaching the median ocellus posteriorly. Clypeus moderately convex anteriorly and remarkably raised in the middle, its medial part much higher than the mandibular plane. Eyes strongly protruding on the sides of the head which is much narrower in front than behind the eyes. Ocelli delimiting a subtriangular area adjecting dorsally over the already prominent frontal area. Antennal scape thick, ca. two times longer than broad and three times longer than the first funicular joint; second funicular joint ca. 1.5 times longer than the scape; third funicular joint slightly shorter; remaining antennomeres thickening from the base to the apex. Mandibles elongate and weakly carinate laterally.

Mesosoma elongate, in dorsal view the sides continuously arched from the anterior pronotal border to the propodeum. Pronotal sides diverging backwards, sometimes with a pair of minute denticles. Mayrian furrows deeply impressed. Mesonotum and scutellum gently convex in sides view. Propodeum with basal and declivous faces making an angle of ca. 100° and separate by a ridge bearing, at its sides, two small teeth. Petiole and postpetiole subequal in length and width, with their maximum width anteriorly. Petiolar node subrectangular; its anterior face truncate and laterally delimited by a pair of denticles. Postpetiole subexagonal. Gaster elongate; its maximum width subequal to the maximum width of the thorax.

Sculpture. Head punctate and covered by irregular foveae and short rugosities; the foveae and the rugosities broader on the posterior part of the head dorsum and on the whole ventral part of the head. Mesosoma punctate and densely covered by foveae more regular than those on the ventral part of the head. Anterior half of the basal face of the propodeum with the same type of sculpture as on the posterior part of the head dorsum; posterior half of the basal face and anterior part of the declivous face with longitudinal rugosities, the rugosities transversal on the posterior part of the declivous face. Pleurae punctate and with longitudinal rugosities on the pro- and lower metapleurae, the rugosities thicker on the lower metapleurae. Meso and upper metapleurae covered by irregular foveae, sparser on the upper mesopleurae. Pedicel punctate and with very thin, irregular, longitudinal rugosities more impressed on the sides. First gastral tergite reticulate; remaining tergites and sternites superficially reticulate and shining. Legs punctate; the punctures more impressed on the tibiae.

Pilosity. Head and mesosoma covered by long, thick, pointed, erect, golden hairs. The same hairs, but rarer, on the sides of the petiole and postpetiole. Gaster, dorsally, only with few short hairs at the end of each segment, practically bald; ventrally, numerous, long, golden hairs as in the worker and in the gyne. Antennae only pubescent. Legs with similar but shorter and appressed, golden hairs.

Colour. Head, mesosoma, petiole and postpetiole, coxae and trochanters black. Gaster and remaining parts of the legs yellowish-brown; antennae brown and opaque.

Measurements (in mm) and indices: TL 11.34-13.88; HL 1.64-1.76; HW 1.80-2.16; EL 0.62-0.72; PW 1.72-2.16; PeW 0.84-0.96; PpW 0.98-1.08; HBaL 1.80-2.08; HBaW 0.25-0.30; CI 109.7-122.7; PI 98.1-104.6; PPeI 179.2-257.1; PPpI 172.0-204.1; HBaI 11.5-15.9.

Type Material

de Andrade and Baroni Urbani (1999):

Gyne. Type locality: "in America meridionali", actually Essequibo (Guyana). Type material: Holotype winged gyne (wings detached) labelled "Essequibo, Smidt, Mus. J. Lund, Cryptocerus atratus (Fabr.) Linn., marginatus Fabr. ", in Zoologisk Museum, University of Copenhagen, examined.

Cephalotes decemspinosus Worker. Type locality: St. Jean du Maroni (French Guyana). Type material: 4 syntype workers from St. Jean du Maroni, French Guyana, Le Moult in Naturhistorisches Museum, Basel (examined), lectotype worker, in Coll. Borgmeier Museu de Zoologia da Universidade de Sao Paulo, designated by Kempf, 1951 same data as the syntypes.

Cephalotes decemspinosus var. spissus (sic). Worker. Type locality: surroundings of the Lucie River (Surinam). Type material: 3 syntype workers labelled Suriname-Exped., Lucie-riv. -Gebied, VII -VIII. 1 926, Naturhistorisches Museum, Basel, examined.

References

  • 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 124, male described, Combination in Cephalotes)
  • Fabricius, J. C. 1804. Systema Piezatorum secundum ordines, genera, species, adjectis synonymis, locis, observationibus, descriptionibus. Brunswick: C. Reichard, xiv + 15-439 + 30 pp. (page 419, queen described)
  • Klug, F. 1824. Entomologische Monographien. Berlin: Reimer, 242 pp. (page 200, Junior synonym of atratus)
  • Roger, J. 1862c. Synonymische Bemerkungen. 1. Ueber Formiciden. Berl. Entomol. Z. 6: 283-297 (page 291, Junior synonym of atratus)