Cephalotes atratus

This species is the largest and one of the commonest of the genus. The mature colonies are composed of several thousands of individuals which, while foraging, can almost cover some tree trunks even in urban areas.

Identification
A member of the atratus clade differing from its sister species Cephalotes marginatus (q. v.) by the sparser pilosity on the ventral part of the gastral sternites of the worker and of the gyne, and, in the male, for the denser foveolation of the mesosoma and by the greater CI. Both sister species (atratus and marginatus) are among the largest of the genus and differ from closely related ones by the lack of crenulation on the posterior half of the frontal carinae. (de Andrade and Baroni Urbani 1999)

Key to Cephalotes Workers

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guyana, Panama, Paraguay, Peru, Suriname, Trinidad and Tobago, Uruguay, Venezuela.

Worker
Minor

Nomenclature

 *  atratus. Formica atrata Linnaeus, 1758: 581 (w.) "AMERICA MERIDIONALI". Latreille, 1802c: 274 (q.); Spinola, 1851b: 47; Spinola, 1853: 63 (m.); Wheeler, G.C. & Wheeler, J. 1954b: 154 (l.). Combination in Cephalotes: Latreille, 1802a: 358; in Cryptocerus: Latreille, 1803: 280; in Cryptocerus (Cephalotes): Wheeler, W.M. 1916c: 12; in Cephalotes: Smith, M.R. 1949c: 19. Senior synonym of quadridens: Retzius, 1783: 76; Latreille, 1802c: 272; Kempf, 1951: 115; of dubitatus: Smith, F. 1858b: 188; of crassispina, nitidiventris, rufiventris and material of the unavailable name dehnowi referred here: Kempf, 1951: 115; of erectus: De Andrade & Baroni Urbani, 1999: 112.
 * quadridens. Formica quadridens De Geer, 1773: 609, pl. 31, figs.17-20 (w.) SURINAM. Combination in Cephalotes: Santschi, 1919f: 44. Junior synonym of atratus: Retzius, 1783: 76; Latreille, 1802c: 272. Revived from synonymy: Santschi, 1919f: 44. Subspecies of atratus: Santschi, 1920f: 148; Forel, 1922: 97. Junior synonym of atratus: Kempf, 1951: 115.
 * dubitatus. Cryptocerus dubitatus Smith, F. 1853: 216, pl. 20, fig. 1 (m.) BRAZIL. Junior synonym of atratus: Smith, F. 1858b: 188.
 * rufiventris. Cryptocerus atratus ab. rufiventris Emery, 1894e: 4 (w.) ARGENTINA. Junior synonym of atratus: Kempf, 1951: 115.
 * crassispina. Cephalotes atratus st. crassispina Santschi, 1920f: 148 (w.) BRAZIL. Junior synonym of atratus: Kempf, 1951: 115.
 * nitidiventris. Cephalotes atratus var. nitidiventris Santschi, 1920f: 148 (w.) FRENCH GUIANA. Junior synonym of atratus: Kempf, 1951: 115.
 * erectus. Cephalotes atratus subsp. erectus Kempf, 1951: 124 (w.q.) PANAMA. [First available use of Cephalotes atratus st. quadridens var. erecta Santschi, 1920f: 149; unavailable name.] Junior synonym of atratus: De Andrade & Baroni Urbani, 1999: 112.

Worker
Kempf (1951) - Monomorphic. Length 8-14 mm. Black; the following fuscous ferruginous: two semitranslucid spots on each frontal carinae, tips of tarsi.

Head subopaque; finely reticulate-punctate. Mandibles densely and finely rugose and punctured. Frontal carinae slightly diverging caudad, scarcely upturned laterad, vestigially crenulate anteriorly with only a few projecting setae, remaining part not crenulate and without setae. Occiput continuous with upper surface of head, inclined ventrad; its angles with a pair of spines. Vertex without spines nor swellings. Lower occipital border straight, carinulate. Upper surface of head and cheeks covered with sparse oval foveolae, containing a short, scalelike, silvery, decumbent hair. Lower surface of head more coarsely reticulate-rugose and foveolate. Apical segment of maxillary palpi somewhat longer than the preceding.

Thorax subopaque. Shoulders obtusely dentate. Scapular spines strong, obliquely inclined backward, and laterad, subacuminate, the apical half more or less recurved, with a small tooth projecting from the anterior face at the bent. Median pronotal spines usually minute, vestigial or absent. Promesonotum moderately longitudinally convex, immarginate laterad. Promesonotal suture distinct. Mesonotum flat, with a minute tubercle laterally toward the posterior angle. Mesoepinotal suture distinct and impressed. The basal face of the epinotum slightly inclined forward, immarginate laterad, slightly constricted in front of the oblique, more or less divergent, straight to slightly curved epinotal spines. Entire thorax finely reticulate-punctate, with sparse setigerous foveolae, crowded and more deeply impressed on pronotum, very sparse on the pleura, leaving free spaces, which arc mostly longitudinally rugose. Mesopleura with a small tooth above the anterior corner of the mid coxae. Declivous face mostly without coarse sculpture. Outer surface of fore coxae transversely striated. Legs without foveolae, but with appressed setae. Oblique setae on apical end of femora, tibiae and on tarsi. Petiole shorter than broad, subcuboidal, denesely foveolate above and on the sides, with a small sidewards projecting tubercle or tooth on each anterior corner. Ventral face strongly keeled, ending anteriorly in an obtuse tooth. Postpetiole more than 1.5 times as broad as long. Sides with a conspicuous, anteriorly angulate, posteriorly rounded swelling, the sides converging caudad. Upper face flat, with a pair of small tubercles on the anterior border. Ventral face with a large, truncate, rounded or bifid lobe, projecting ventrad and somewhat cehalad. Sculpture as on petiole.

Gaster elliptical, subopaque to subfulgid, finely reticulate-punctate, covered with larger, elongate, shallow grooves, containing a decumbent hair. Posterior half of first sternites and the exposed portion of the tergites and sternites 2-4 with sparse, suberect, pale-brownish hairs.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 7.64-15.10; HL 1.60-3.30; HW 2.08-4.50; EL 0.48-0.80; PW 1.88-4.80; PeW 0.50-1.00; PpW 0.59-1.08; HBaL 1.32-2.30; HBaW 0.34-0.51; CI 130.0-136.4; PI 93.7-112.9; PPel 349.3-480.0; PPpl 317.9-444.4; HBal 22.2-25.7.

Queen
Kempf (1951) - Length up to 23 mm. Somewhat similar to the worker. Black, subopaque. Head somewhat broader than long. Mandibles strongly rugose. Clypeus much broader than long, subtriangular. Frontal carinae distinctly converging anteriorly, not parallel not upturned laterally, slightly crenulate on anterior third, with a few projecting setae. Vertex with a pair of obtuse swellings, just in front of the subtruncate occiput. Occipital angles bituberculate. Cheeks immarginate below. culpture as in worker. Thorax subopaque. Pronotum immarginate cephalad and laterad. Shoulders low, bluntly angulate. Scapular spines short, stout, acute. Transverse crest of pronotum vestigial, not carinate, two median pronotal spines short, obtuse. Mesopleura with a small tooth above the mid coxa. Epinotum narrow, immarginate, laterad, spines short, icrassate at base, apices slightly diverging, their interapical distance less than 1/2 of the maximum width of thorax. Declivous face twice as long as basal face of epinotum. Sculpture as on head. Basitarsus of mid and hind leg flattened and broadened, not as thin as in worker. Petiole short, about twice as broad as long, the upper face presenting a transverse keel. Postpetiole longitudinally, greatly convex, with a large, blunt, rounded swelling laterad, about twice as broad as long. Ventral lobe less conspicuous than in worker. Both peduncular segments coarsely and rather densely foveolate. Gaster as in worker, more elongate, sides subparallel, the microsculpture less prominent; first tergite rather fulgid discad, sparsely foveolate, the foveolae smaller than on thorax and on head. Wings infumated. Fore wing with fuscous stigma and a dark streak along the subcostal vein. Marginal cell closed and appendiculate. Submarginal cell shorter than in Zacryptocerus clypeatus. Transverse cubital vein absent, the cubital vein touching the marginal cell. Second abscissa of subcostal vein shorter than the section of basal vein that encloses the submarginal cell. Occasionally stubs projecting from the cubital vein into the ubmarginal cell and the apical field.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 15.06-19.50; HL 2.76-3.65; HW 3.32-4.50; EL 0.64-0.80; PW 2.60-4.50; PeW 0.96-1.40; PpW 1.16-1.60; HBaL 1.76-2.00; HBaW 0.486-0.60; CI 120.0-126.5; PI 93.3-127.7; PPeI 270.8-321.4; PPpI 224.1-281.2; HBaI 27.3-30.0.

Male
Kempf (1951) - Length 13.2 mm. Median head length 1.53 mm. Weber's length of thorax 4.05 mm. Black: the following brunneous: antennae, coxae, trochanters, base of femora. Orange-brown: gaster, femora, tibiae, tarsi.

Head, without mandibles much broader than long (103 : 63). Mandibles finely rugulose and punctate; chewing border with distinct apical and preapical tooth. Clypeus transverse, anterior face truncate, subperpendicular to upper surface of head, posterior half at right angles to it; horizontal. Anterior border straight, posterior border marked by a deep transverse depression in front of the antennal sockets. Entire clypeus finely shagreened. Frontal carinae scarcely expanded, divergent caudad, fading out before the posterior border of eye. Antennal scrobes indistinct. Ocelli on vertex, conspicuous, subequal to diameter of second funicular segment. First funicular segment shorter than broad. Second funicular segment longer than the following, except of the apical segment.

Thorax subopaque, almost twice as long as maximum width (83 : 47). Pronotum immarginate laterad, with a minute tooth on the anterior angle, and a longer blunt tooth somewhat behind; rugose-reticulate and foveolate. Scutum convex with deeply impressed Y-shaped Mayrian furrows, antero-mesal part deeply and densely foveolate, postero-lateral portion more sparsely and shallowly foveolate. Scutellum similarly sculptured with anterolateral lobes almost constricted off by a deep transverse furrow immediately behind the anterior border. Basal face of epinotum shorter than declivous face, transversely convex, immarginate laterally, posterior corners with a sharp carinule, reticulate-rugose and foveolate. Declivous face finely reticulate, subfulgid, with a few faint, distinct rugulae. Sides of mesothorax finely shagreened anteriorly, sparsely, shallowly foveolate and rugose posteriorly. Basitarsi elongate, compressed.

Petiole subopaque, slightly broader than long, anterior face truncate, excavate, the sides somewhat converging behind, finely shagreened above, finely longitudinally rugose laterad, and reticulate-rugose antero-laterad. Postpetiole broader than long, sides greatly convex, subtuberculate, sculptured as petiole.

Gaster subopaque, short, fusiform, finely shagreened. Subgenital plate transverse, apical border rounded.

Wings leathery, infumated. Veins brunneous. Fore wings with fuscous stigma, and fuscous streak along the subcostal vein. Marginal cell closed and appendiculate. Discoidal cell extremely small. Transverse cubital vein present, cubital vein not touching the marginal cell.

Pilosity gold-brown. Antennae with dense fine pubescence. Long dense hair on head and thorax; sparse, appressed on first gastral tergite, erect on apical border of the gastral tergites and sternites.

Certain features are highly variable, even among males of the same nest. Among those are the occipital spines, which may form mere perpendicular carinule on each side, or even be quite obsolete. The same is true for the carinules on the posterior corner of the epinotum, which may be occasionally tooth-like. The sculpture in some instances is coarser than in the specimen described above. The following variability occurs in the fore wing: discoidal cell always small, sometimes minute, open or even completely absent. Stubs projecting into submarginal cell from various places of the recurrent and the cubital veins.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 9.78-13.21; HL 1.28-1.68; HW 1.68-2.16; EL 0.53-0.70; PW 1.60-2.24; PeW 0.72-0.92; PpW 0.88-0.96; HBaL 1.32-1.84; HBaW 0.18-0.26; CI 128.3-131.9; PI 96.4-105.0; PPeI 227.3-272.2; PPpI 208.3-233.3; HBaI 13.3-15.1.

Type Material


de Andrade and Baroni Urbani (1999):

Worker. Type locality: “America meridionalis”. Type Material not available for the present study.

Formica quadridens. Type locality: Surinam.

Cryptocerus dubitatus. Male. Type locality: Brazil. Type material presumably lost (neither in the BMNH nor in ).

Cryptocerus atratus ab. Rufiventris. Worker. Type locality: Tucuman (Argentina). Type material not available for the present dtudy.

Cephalotes atratus var. nitidiventris. Worker. Type locality: Cayenne and Lumier River (French Guyana). Type Material: 2 syntype workers labeled “America, Cayena 1905, E. Grouvelle” (sic) in, examined.

Cephalotes atratus stirps crassispina. Worker. Type localities: Mato Grosso (Brazil), Formosa (Misiones, Argentina), and Santa Trinidad (Paraguay). Type material 3 workers from Urucuru, Mato Grosso (Silvestri), 3 workers from Formosa (Argentina, Joergensen), 1 worker from Paraguay without further data, all in NHMB, examined.