Cephalotes angustus

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Cephalotes angustus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. angustus
Binomial name
Cephalotes angustus
(Mayr, 1862)

Cephalotes angustus casent0173660 profile 1.jpg

Cephalotes angustus casent0173660 dorsal 1.jpg

Specimen labels

Synonyms

Nothing is known about the biology of Cephalotes angustus.

Identification

de Andrade and Baroni Urbani (1999) - A member of the angustus clade differing from its closest outgroup species, Cephalotes targionii, in the worker, by the marginate gaster, and, in all female castes, by the anterior face of the petiole less oblique and more truncate and, from the in group species, Cephalotes pallidicephalus, in the worker, soldier and gyne by the absence of longitudinal rugosities on the first gastral sternite. Also see the nomenclature section below for notes about morphological variation.

This species is the largest of the angustus clade; except for the size, which is often subject to individual variation, it is very similar to targionii, Cephalotes notatus and pallidicephalus.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina, Brazil (type locality).


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.

  • angustus. Cryptocerus angustus Mayr, 1862: 759 (s.q.) BRAZIL. Mayr, 1887: 566 (w.m.). Combination in Paracryptocerus (Harnedia): Kempf, 1958a: 20; in Zacryptocerus: Brandão, 1991: 384; in Cephalotes: Baroni Urbani, 1998: 319. Senior synonym of clarior: Kempf, 1958a: 74; of ruficeps: De Andrade & Baroni Urbani, 1999: 700.
  • clarior. Cryptocerus angustus var. clarior Forel, 1912e: 201 (w.) BRAZIL. Junior synonym of angustus: Kempf, 1958a: 74.
  • ruficeps. Cryptocerus (Cryptocerus) cristatus var. ruficeps Santschi, 1929d: 301 (s.) BRAZIL. Junior synonym of cristatus: Kempf, 1951: 216; of angustus: De Andrade & Baroni Urbani, 1999: 700.

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

de Andrade and Baroni Urbani (1999) - Cephalotes angustus exhibits great variability, the most important traits of which appear to be: in the workers, the sides of the pronotum may have three or four denticles and those of the propodeum three to five (those with 4-5 denticles correspond to Forel's var. clarior); the maculae of first gastral tergite vary in width and length; the frontal carinae may be more or less upturned over the eyes; the vertexal angles bear lamellae developed to different extents; the first gastral sternite may bear on the sides only few, irregular, longitudinal, thin, rugosities; in the soldiers and in the gynes, the floor of the disc can be flat or slightly convex, the foveae on the disc more or less dense, the frons may bear or not a black spot, the pronotum may have a lateral pair of yellow to dark red strips of variable size, the gastral spots may vary in colour and size or may be fused in a long yellow strip. The density of the disc foveae is particularly great in the unique type of the var. ruficeps Santschi (Brazil) and among three soldiers and two gynes from Represa Rio Grande, Guanabara (Rio de Janeiro): they might represent a separate species. On the other hand, we have seen specimens of undoubted angustus from other localities of the same state.

Description

Worker

Kempf (1958) – Total length 4.0-6.2 mm; maximum length of head 1.18-1.75 mm; maximum length of thorax 1.18-1.82 mm. Black; the following ferruginous: apex of mandibles, scape and last funicular segment, edge of frontal carinae and occipital lobes, tibiae, the four apical tarsites, anterolateral corners of gaster just inside of the pale, translucid crest; remaining portions of frontal carinae pale testaceous.

Head subopaque, subquadrate; its maximum length subequal to the distance between the eyes, usually slightly longer. Clypeal suture vestigial. Lateral border of head slightly diverging caudad, the posterior portions distinctly sinuate and upturned above eyes. Occipital corners obliquely truncate, the inner angle of the truncation forming a toothlike, apically rounded, projecting lobe. Occipital border deeply emarginate. Dorsal face of head moderately convex discally, finely reticulate-punctate, more sparsely covered with squamiferous foveolae, which become more numerous and crowded toward the occipital border. Lower face of head finely reticulate-punctate, somewhat shiny, and reticulate-rugose disc ally and cephalad.

Thorax subopaque. Anterior border of pronotum oblique laterad, straight and transverse mesally. Shoulders subacute. Sides of pronotum with two approximated triangular teeth, followed by a more or less sinuate, or even very obtusely angulate, crest, the posterior corner rectangular or obtuse. Promesonotal suture vestigial or absent. Mesonotum with a blunt or rectangular tooth projecting from each side. Mesoepinotal suture vestigial or absent, usually marked only near the lateral border. Lateral border of basal face of epinotum tridentate: the first tooth, forming the anterior corner of the basal face, small and subrectangular, followed by a second, much larger, acute tooth, and a third, again smaller, tooth, which however is acute and usually points more or less caudad. Between the second and third tooth often a minute, scarcely visible, denticle. Declivous face discally excavated, relatively well differentiated from the basal face, its lateral borders marginate. Dorsum of thorax finely reticulate-punctate rather densely covered with squamiferous foveolae, especially so along the lateral border. Laterotergite of pronotum with a few longitudinal rugosities near its inferior border. Thoracic pleura densely covered with squamiferous foveolae. Fore coxae reticulate-punctate.

Peduncular segments subopaque, the dorsolateral sculpture as on dorsum of thorax and head. Petiole subequal in width to postpetiole, its anterior face obliquely truncate, finely reticulate-punctate and somewhat shining, its superior corners slightly projecting above the dorsal face in the form of a pair of very small denticles. Anterior corners of petiole rounded, the sides with an acute spine, pointing laterad and slightly caudad. Postpetiole with a similar, slightly recurved spine on each side, its dorsal face strongly convex, both longitudinally and transversely.

Gaster subopaque, elliptical, strongly emarginate antero-mesially, the anterolateral border with a hyaline, thin crest, which extends backwards on the sides beyond the conspicuous stigma of the first tergite, and continues caudad as a distinct margination reaching almost the posterior border of the same tergite, which is finely reticulate and superficially foveolate. Foveolae longer and smaller than on thorax. First sternite finely, yet sharply reticulate-punctate, usually without longitudinal rugosities.

Standing hair on mandibles, anterior border of clypeus, along the edge of the frontal carinae and the posterior border of the gastral tergites and sternites. Decumbent hair in the form of short, thick, canaliculate, highly shining scales, on the dorsum of body, cheeks, pleura, and extensor face of femora. Similar scales, but longer, simple on the sides of femora, tibiae, lower face of head and the first gastral sternite.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 4.40-6.58; HL 1.08-1.48; HW 1.26-1.74; EL 0.29-0.40; PW 1.00-1.52; PeW 0.62-0.78; PpW 0.62-0.81; HBaL 0.44-0.64; HBaW 0.10-0.16; CI 112.3-120.0; PI 117.1-131.20; PPeI 161.3-194.9; PPpI 161.3-1 93.9; HBaI 22.7-26.7.

Soldier

Kempf (1958) – Total length 6.2-8.5 mm; maximum length of head 1.85-2.50 mm; maximum length of thorax 1.78-2.28 mm. Black; upper half of sides of head and floor of cephalic disc more or less reddish-brown, the latter usually, not always, with a large, elongate, anteromedian black spot; marginate edge of cephalic disc infuscated; tip of scape, tibiae, tarsites ferruginous; extensor face of tibiae lighter in color; first gastral tergite with the customary four yellowish spots, the pair of each side often confluent.

Head somewhat shiny; surmounted by a subquadrate, very seldom elongate, flat, completely marginate disc. Borders of disc scarcely crenulate and very little raised, not concealing the floor of the cephalic disc, when seen in profile. Anterior portion of disc semicircular, its sides subparallel up to some distance behind the posterior border of the eyes, where they form an obtuse angle and converge strongly mesad to meet the truncate, straight, transverse posterior border. Clypcal sutures vestigial. Floor of disc slightly excavate and a little transparent above the antennal scrobes. Occipital lobes sharply marginate, their lateral border convex, forming a blunt tooth at the posterior corner. Floor of disc and sides of head very finely and densely punctate, more sparsely foveolate. Lower face of head more shiny, microsculpture and foveolae more superficial, the latter very sparse.

Thorax shiny on dorsum, opaque on sides. Pronotum nearly as broad as head, its anterior angle with a triangular tooth, its sides excised behind the tooth, then convex at the level of the transverse carina, the following part strongly converging mesad and a little sinuous. Transverse pronotal carina usually very pronounced, the lateral portions concave, strongly raised and sharply edged, the median portion convex, less prominent, only bluntly marginate in the middle. Promesonotal suture usually only vestigial. Sides of mesonotum with an obliquely truncate, projecting, marginate lateral lobe. Mesoepinotal suture deeply impressed laterad, slightly marked or only vestigial or even absent in the middle. Basal face of epinotum very short and broad, its sides with a broad triangular tooth and its posterior corner with a strong tooth projecting upward and laterad. Sculpture of dorsum of thorax as on floor of cephalic disc, the squamiferous foveolae smaller and more crowded. Laterotergite of pronotum very sparsely foveolate, usually with a few rugosities near the inferior border. Pleura more densely foveolate on the inferior half. Fore coxae occasionally with a few transverse rugosities on the external face, near the apex, but usually only reticulate-punctate. Peduncular segments, in general, as in worker, the lateral spines stouter, solid, those of petiole more conspicuously recurved.

Gaster elliptical, the tergites subopaque, the sternites slightly more shining. Distinctly emarginate anteromesially at the postpetiolar insertion, the anterolateral border sharply marginate, the anteriormost portion usually very narrowly crested. Lateral margination of first tergite ending near the stigma. First tergite finely reticulate-punctate, the squamiferous foveolae more superficial and elongate. First sternite similarly sculptured, often with a few fine longitudinal rugosities anterolaterally.

Standing hair on mandibles and tip of gaster. A fringe of very sparse and thickish hair projecting from the anterolateral border of the cephalic disc. Squamiform hair decumbent, always in foveolae, similar to those of worker, always highly shiny, with reflexes of polished brass.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 6.96-8.92; HL 1.64-2.46; HW 1.84-2.60; EL 0.39-0.48; PW 1.64-2.60; PeW 0.72-0.95; PpW 0.72-1.00; HBaL 0.58-0.73; HBaW 0.16-0.22; CI 105.7-112.2; PI 100.0-112.2; PPeI 226.4-273.7; PPpI 221.5-260.0; HBaI 27.6-30.1.

Queen

de Andrade and Baroni Urbani (1999) - Head with a complete disc, weakly concave anteriorly and gently convex posteriorly. Frontal carinae superficially crenulate. Sides of the disc converging before the eyes and connected posteriorly by a truncate or convex border. Vertexal angles convex and with a well marked obtuse margin. Clypeal border concave and with a pair of external denticles. Mandibles with a strong carina. Dorsal border of the antennal scrobes with a thick carina ending in a small denticle just before the eyes. Eyes gently convex and not hidden by the disc.

Mesosoma. Anterior pronotal border convex and covering the scapular angles in dorsal view in most specimens. Pronotal carina visible but superficial on the sides. Mesonotum and scutellum on the same plane and flat. Propodeum well differentiate in basal and declivous faces. Basal face with subparallel sides, slightly converging posteriorly and bearing a pair of small denticles and a pair of triangular teeth slightly diverging. Sides of the declivous face converging posteriorly.

Anterior face of the petiole oblique. Sides of the petiole with a small denticle. Postpetiole convex and with an incomplete V-shaped carina in the middle. Postpetiolar sides with a pair of thick, pointed spines arising from the anterior border and directed anterolaterally.

Gaster oval, with a pair of broad, protruding anterolateral lobes. Anterolateral borders of the first gastral tergite with a very narrow margin not reaching the stigma posteriorly.

Hind femora without angles or denticles. Hind basitarsi slightly more compressed apically than distally, and with subparallel sides.

Sculpture. Head dorsum minutely and superficially punctate, shining and covered with variably clumped foveae, larger on the frons. Ventral part of the head reticulate-punctate, variably shining and with sparse foveae. Mesonotum, pedicel and distal part of the outer face of the femora and outer face of the tibiae reticulate-punctate, with foveae of different size and variably clumped, more round on the pronotum, mesonotum and scutellum, denser on the basal face of the propodeum, on the pedicel and on the upper mesopleurae. Gaster and remaining parts of the legs reticulate-punctate. Anterior fifth of the first gastral tergite with superficial foveae. Some specimens with the sides of the first gastral sternite with few, irregular, longitudinal rugosities.

Pilosity. Each fovea with an appressed canaliculate hair. Body parts without foveae with sparse, appressed, thin, slightly canaliculate hairs. Sides of the frontal carinae and of the disc, mesonotum, pedicel, gaster and legs with sparse, slightly clubbed, erect hairs. First gastral sternite with rare, long, subtruncate, erect hairs.

Colour. Black. Upper half of the head dorsum dark orange to light brown with blackish frons. First gastral tergite with two pairs of orange-reddish spots, the first pair anterolateral and the second one close to the posterior border; few specimens without or with spots poorly developed; sometimes the first gastral tergite with a long, yellow strip on the sides. Femora dark brown to black, sometimes the distal half of the fore femora dark orange-brown. Tibiae and tarsomeres dark orange to brown, tarsi darker.

Measurements (in mm) and indices: TL 9.12-11.38; HL 1.92-2.40; HW 1.88-2.52; EL 0.41-0.50; PW 1.76-2.40; PeW 0.72-0.90; PpW 0.8 l-1.08; HBaL 0.64-0.80; HBaW 0.l8-0.27; CI 97.9-105.0; PI 100.0-108.5; PPeI 231.6-266.7; PPpI 207.4-222.2; HBaI 27.5-32.5.

Male

de Andrade and Baroni Urbani (1999) - Differing from that of Cephalotes targionii in the following details:

Head more convex dorsally. Vertexal angles obtuse. Frons flat. Mesosoma more robust. Anterior pronotal border straight. Humeral angles weakly marked. Pronotal sides subparallel. Petiole and postpetiole shorter and broader. Sides of the postpetiole with a larger denticle. Gaster narrower than the mesosoma.

Sculpture. Body less shining, more opaque and covered by more impressed reticulation. Head, mesosoma and sides of the pedicel with superficial foveae; the foveae separate by irregular, short rugosities on the head, denser on the posterior third of the head dorsum, on the pronotum and on the basal face of the propodeum. Basal face of the propodeum with additional, irregular rugosities between the foveae. Pleurae with few longitudinal rugosities. Pedicel with few, thin, longitudinal rugosities. Gaster and legs reticulate, the reticulation more impressed on the first tergite.

Wings as in the gyne.

Pilosity. Erect hairs shorter and sparser, less abundant on the posterior borders of the gaster.

Colour. Head, mesosoma, pedicel, gaster and coxae black. Proximal half of the femora light brown. Remaining parts of the legs yellowish.

Measurements (in mm) and indices: TL 5.18-6.40; HL 0.80-0.96; HW 1.00-1.22; EL 0.43-0.55; PW 1.04-1.28; PeW 0.43-0.55; PpW 0.46-0.60; HBaL 0.55-0.75; HBaW 0.07-0.12; CI 125.0-127.1; PI 95.3-96.1; PPeI 232.7-241.9; PPpI 213.3-226.1; HBaI 12.7-14.7.

Type Material

de Andrade and Baroni Urbani (1999):

Worker and gyne. Type locality: Brazil. Type material: not available in the Mayr collection in the Naturhistorisches Museum Wien, Vienna; as already noted by Kempf (1958) a series of 2 soldiers, 2 workers and 1 male from Santa Catharina in Naturhistorisches Museum Wien, Vienna, labelled as types and collected by Hecko cannot represent the true types. We regard as probable syntypes 2 workers and 1 soldier labelled “c. angustus Mayr, Bresil, cotypus”, in Musee d'Histoire Naturelle Genève.

Cryptocerus angustus var. clarior. Worker. Type locality Rio de Janeiro. Type material 9 syntype workers partly labelled “Cr. angustus Mayr v. clarior For. type, Rio, Goldi III,” and partly “Prov. Rio, Goldi, III, Cr. angu,tus Mayr var. clarior Forel” in MHNG and Naturhistorisches Museum, Basel, examined. One specimen without head and gaster in Musee d'Histoire Naturelle Genève selected as lectotype by Kempf (1951) according to the label.

Cryptocerus cristatus var. ruficeps. Worker. Type locality: Brazil. Type material: holotype, unique in NHMB with two labels; first label: “Bresil, K. Zubac” (sic); second label: “Cryptocerus angustus Mayr V. ruficeps (cancelled) Santschi det. 19 (printed) 4”, examined.

References

  • 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 319, 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 384, Combination in Zacryptocerus)
  • De Andrade, M. L.; Baroni Urbani, C. 1999. Diversity and adaptation in the ant genus Cephalotes, past and present. Stuttg. Beitr. Naturk. Ser. B (Geol. Paläontol.) 271: 1-889 (page 700, Senior synonym of ruficeps)
  • Kempf, W. W. 1958a. New studies of the ant tribe Cephalotini (Hym. Formicidae). Stud. Entomol. (n.s.) 1: 1-168 (page 20, Combination in Paracryptocerus (Harnedia); page 74, Senior synonym of clarior)
  • Mayr, G. 1862. Myrmecologische Studien. Verh. K-K. Zool.-Bot. Ges. Wien 12: 649-776 (page 759, soldier, queen described)
  • Mayr, G. 1887. Südamerikanische Formiciden. Verh. K-K. Zool.-Bot. Ges. Wien 37: 511-632 (page 566, worker, male described)