Cephalotes quadratus

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Cephalotes quadratus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. quadratus
Binomial name
Cephalotes quadratus
(Mayr, 1868)

Cephalotes quadratus casent0173705 profile 1.jpg

Cephalotes quadratus casent0173705 dorsal 1.jpg

Specimen labels

Synonyms

Nothing is known about the biology of Cephalotes quadratus.

Identification

A member of the fiebrigi clade differing from the two species of its sister subclade, Cephalotes guayaki and Cephalotes fiebrigi, in the worker and soldier by the absence of erect hairs on the head, mesosoma and pedicel. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina (type locality), Paraguay.

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Cephalotes quadratus for further details

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

Worker

Nomenclature

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

  • quadratus. Cryptocerus quadratus Mayr, 1868b: 175 (s.) ARGENTINA. Emery, 1896h: 634 (w.q.). Combination in Paracryptocerus (Harnedia): Kempf, 1958a: 33; in Zacryptocerus: Brandão, 1991: 388; in Cephalotes: De Andrade & Baroni Urbani, 1999: 660. Senior synonym of convexus: Kempf, 1958a: 33.
  • convexus. Cryptocerus convexus Santschi, 1916e: 382, fig. (w.) ARGENTINA. Junior synonym of quadratus: Kempf, 1958a: 33.

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) - Head broader than long and strongly convex dorsally. Vertexal angles round and with an obtuse denticle medially. Vertexal margin narrowly concave. Frontal carinae concave in front of the eyes and sinuous over the eyes. Mandibles laterally carinate.

Mesosoma strongly convex in side view. Scapular angles visible in dorsal view. Pronotum with a narrow lateral lamella bearing three pairs of irregular teeth, the first pair larger and obtuse and the second and third ones round. Sides of mesonotum with a pair of small denticles. Promesonotal suture poorly impressed. Propodeal suture impressed. Propodeum with differentiate basal and declivous faces and with the sides narrowing backwards; sides of the basal face of the propodeum with two pairs of teeth, the first pair simply angulate and the second one larger and pointed; sides of the declivous face of the propodeum unarmed, or with one or two small pairs of denticles.

Petiole anteriorly truncate; its anterior border weakly concave medially. Petiolar dorsum with a transversal carina separating its anterior face from the posterior one. Petiolar spines well developed arising from the anterior face of the petiole, pointed and strongly curved backwards. Postpetiole slightly broader than the petiole; its lateral expansions broad, spiniform, developed and directed anteriorly, strongly curved and pointed backwards.

Gaster suboval, with a pair of broad, anterolateral lobes.

Mid and hind femora not angulate; mid and hind basitarsi flat and with subparallel sides.

Sculpture. Body slightly shining, minutely and superficially reticulate-punctate. Head, mesosoma, pedicel and outer face of the femora and tibiae superficially foveolate, the foveae more impressed close to the vertexal margin and on the pronotum, irregular on the lower pleurae, on the pedicel and on the outer face of the femora and tibiae, rare or absent on the frontal carinae, on the declivous face of the propodeum, on the propleurae and on the upper meso- and metapleurae. Propleurae with additional thin, longitudinal rugosities.

Pilosity. Body with four types of hairs: (1) appressed and generally originating from each fovea; similar hairs on some body parts without foveae; (2) subclavate and rare on the border of the frontal carinae and on the legs; (3) subtruncate and rare on the dorsum of the first gastral tergite, sparse on the corresponding sternite; similar hairs but longer on the posterior borders of the gastral segments; (4) long, pointed and rare on the posterior borders of the sternites.

Colour. Brown. Frontal carinae dark yellow-orange.

Measurements (in mm) and indices: TL 4.26-4.56; HL 1.00-1.08; HW 1.06-1.16; EL 0.30-0.36; PW 0.92-1.00; PeW 0.58-0.62; PpW 0.60-0.65; HBaL 0.36-0.39; HBaW 0.07-0.08; CI 106.0-107.4; PI 115.2-116.0; PPeI 158.6-161.3; PPpI 153.3-153.8; HBaI 19.4-20.5.

Soldier

Kempf (1958) - Total length about 6.4 mm (not accurately measured when type was available); maximum length of head 1.62 mm; of thorax 1.80 mm. Fuscous-brown to black; anterolateral portions of head disc and shoulders reddish-brown; antennae and legs rufo-testaeeous. First gastral tergite quadrimaculate, the spots being yellow, rather small, the posterior pair at some distance from the apical border. Integument slightly shining.

Head subquadrate but slightly longer than broad (67:65), surmounted by an incompletely marginate disc, i e. anteriorly, anterolaterally and posteriorly the disc is sharply marginate, forming a slightly raised crest, which is distinctly crenulate anterolaterally. Postero-laterally, above eyes and the occipital lobes, the border is obsolete and the upper face is continuous with the sides of the head. In profile, the head is strongly convex above. Transversely, the disc is concave in front, gently convex behind. Clypeal sutures vestigial. Eyes situated behind and slightly above the antennal scrobe. Penultimate funicular segment nearly twice as long as the preceding segment. Occipital angles subrectangular and slightly crested. Head disc, occiput and sides coarsely reticulate-rugose and foveolate, with suberect, slightly curved and spatulate hair arising from each pit.

Thorax longer than broad (74:59). Shoulders distinctly dentate. Promesonotum conspicuously convex, as seen in profile. Transverse pronotal carina distinct at the sides, obsolete in the middle. Lateral border of dorsal face of pronotum distinctly marginate in front of the transverse carina, immarginate and rounded behind. Promesonotal suture vestigial at the sides, absent in the middle. Lateral borders of mesonotum forming a rounded, projecting lobe on each side. Mesoepinotal suture impressed, rather deeply laterally, more superficially in the middle. Sides of basal face of epinotum immarginate, with a projecting tubercular swelling. The posterior corner with an obtuse, stout, tubercular tooth. Posterior border, between the teeth, gently emarginate, not forming a marginate edge between the basal face and the declivity, which forms about a right angle with the former. Sculpture of dorsum of thorax almost as on head disc, but the pits are sparser, and the hairs arising from them are decumbent, silvery. Sides of thorax with still more scattered foveolae and the intervening spaces reticulate-rugose, the intervals between the rugosities being finely punctate. Extensor face of tibiae rugulose. Femora fusiform, tibiae and tarsi subcylindrical.

Petiole, in dorsal view, with evenly curved anterior border, which continues laterally as the anterior border of the recurved spines. In the middle, the body of the petiole has a gently impressed longitudinal furrow, flanked on each side by a vestigial swelling. From spine to spine, across the body of the segment extends a bluntly edged, sinuate, transverse carina. Postpetiole slightly broader than petiole, its lateral spines in the form of a pigeon wing, pointing obliquely cephalad at base, strongly recurved caudad. Transverse, blunt carina present, forming a feeble tooth middorsally. Both peduncular segments irregularly rugose, with longer, appressed scalelike hair.

Gaster deeply excised anteriorly, between the projecting, more or less rounded, anterolateral lobes, the border of which is neither crested nor lamellate. Gaster elongate, almost twice as long as broad, its sides subparallel. First tergite finely and densely punctate, with long, appressed, scalelike hair at base, the rest being subglabrous. The apical end of the following tergites and the sternites bear short, sparse, suberect hairs.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 6.48; HL 1.48; HW 1.48; EL 0.34; PW 1.40; PeW 0.72; PpW 0.76; HBaL 0.39; HBaW 0.10; CI 100.0; PI 105.7; PPeI 194.4; PPpI 184.2; HBaI 25.6.

Type Material

de Andrade and Baroni Urbani (1999):

Soldier. Type locality: Estancia Salvador near San Luis (San Luis, Argentina). Type material: Holotype soldier labelled “Salvador, Strobel. 9., Collect. G. Mayr, quadratus, G. Mayr Type” in Naturhistorisches Museum Wien, Vienna (Kempf, 1958 a: 34), examined.

Cryptocerus convexus. Worker. Type locality: Estacion Sosa (Entre Rios, Argentina). Type material: 3 syntype workers labeled “Argentine, Entre Rios, Estacion Sosa, Mac Donagh”, in Naturhistorisches Museum Basel; 1 worker (probably syntype) labelled “Est. Sosa, Cryptocerus convexus”, in Museu de Zoologia da Universidade de Sao Paulo, all 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 388, 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 660, Combination in Cephalotes)
  • Emery, C. 1896h. Formiciden, gesammelt in Paraguay von Dr. J. Bohls. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 9: 625-638 (page 634, worker, queen described)
  • Kempf, W. W. 1958a. New studies of the ant tribe Cephalotini (Hym. Formicidae). Stud. Entomol. (n.s.) 1: 1-168 (page 33, Combination in Paracryptocerus (Harnedia), senior synonym of convexus)
  • Mayr, G. 1868b. Formicidae novae Americanae collectae a Prof. P. de Strobel. Annu. Soc. Nat. Mat. Modena 3: 161-178 (page 175, soldier described)