Cephalotes fossithorax

Identification
A member of the fiebrigi clade differing from its next outgroup species, Cephalotes jheringi, and from its next ingroup species, Cephalotes supercilii, in the worker, soldier and gyne by the erect, very short, truncate body hairs.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina.

Nomenclature

 *  fossithorax. Cryptocerus fossithorax Santschi, 1921h: 125, fig. 1 (s.w.) ARGENTINA. De Andrade & Baroni Urbani, 1999: 638 (m.). Combination in Paracryptocerus (Harnedia): Kempf, 1958a: 58; in Zacryptocerus: Brandão, 1991: 386; in Cephalotes: De Andrade & Baroni Urbani, 1999: 635.

Worker
Kempf (1958) - Total length 3.8-4.7 mm; maximum length of head 1.09-1.37 mm; of thorax 1.07-1.28 mm. Very close to Cephalotes jheringi, from which it differs by the ensemble of the following features:

Color reddish-brown; dorsum of body, especially of head, more or less infuscated; legs usually lighter, yellowish-brown. One specimen is nearly black, with fuscous-ferruginous legs. Shape of head variable, subquadrate to subrectangular (but cephalic index: 0.88-0.90, definitely above bivestitus, with which it agrees to some extent in the shape of the lateral thoracic crest). Sides of head slightly emarginate above eyes, especially in larger specimens, which also show an apparently more elongate head. Sides of pronotum usually, not always, little converging caudad, its border with a denticulate crest. This crest contains at least two of four distinct, acute, strong teeth, and inbetween theses teeth smaller denticles. All teeth are foliaceous. Sides of mesonotum either straight or weakly dentate. Mesoepinotal suture distinct only laterally, absent in the middle. Anterior corner of basal face of epinotum with an obtuse, smaller tooth, followed posteriorly by a larger triangular tooth. Inferior corner of declivous face angulate, or even dentate. Peduncular segments of equal width. Petiole with strong lateral tooth, pointing obliquely backwards. Postpetiole with the customary lateral spines, the tips of which are rounded in front, and pointed behind. Postpetiole strongly convex dorsally. Anterolateral lobes of the usually rather short gaster thick, prominent, rounded, their borders at most very bluntly marginate, not depressed, nor forming a thin edge. Sculpture and pilosity not visibly different from peltatus.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 3.77-4.36; HL 0.88-1.04; HW 0.98-1.14; EL 0.24-0.27; PW 0.83-0.97; PeW 0.47-0.51; PpW 0.40-0.51; HBaL 0.27.0.37; HBaW 0.09-0.11; CI 109.6-111.4; PI 117.5-118.1; PPeI 176.6-190.2; PPpI 169.4-190.2; HBaI 29.7-33.3.

Soldier
Kempf (1958) - Total length 6.5-7.3 mm; maximum length of head disc 1.75-2.10 mm; of thorax 1.71-1.86 mm. Likewise very similar to jheringi, except for the combination of the following features:

Black; anterolateral portion and lateral border of cephalic disc yellow to reddish-brown; a yellowish spot on each shoulder of the larger specimen. Gaster and legs fuscous-ferruginous. Head disc completely marginate, more or less rounded postero-laterally; lateral borders not raised, especially in larger specimen, which has the anterolateral portion of disc completely flat, not excavated. Clypeus with less pronounced teeth on the anterior border, its lateral sutures less distinct than in jheringi, not forming a prominent ridge. Foveolae of floor of head disc slightly more crowded than in jheringi, about 18 pits in a transverse row at the level of the eyes. Occipital lobes with a blunt tooth. Thorax with a transverse pronotal carina, which is not interrupted mesally in the larger worker. Apex of lateral mesonotal lobe not truncate, but subtriangular. Sides of basal face of epinotum without a prominent lateral lobe in larger specimen, with a triangular lobe in smaller specimen. Sculpture and pilosity much the same as in jheringi, with the exception of the projecting setulae on the rim of the head disc, which are fine and pointed at tip.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 5.94-7.06; HL 1.44-1.72; HW 1.54-1.80; EL 0.32-0.36; PW 1.48-1.72; PeW 0.65-0.80; PpW 0.66-0.84; HBaL 0.37-0.43; HBaW 0.11-0.14; CI 104 .6-106.9; PI 104.0-104.6; PPeI 215.0-227.7; PPpI 204.8-224.2; HBaI 29.7-32.5.

Queen
de Andrade and Baroni Urbani (1999) - Head almost flat to slightly concave anteriorly and gently convex posteriorly, with disc. Sides of the disc strongly crenulate; posterior part of the sides of the disc converging before the eyes and connected with a faint, convex carina. Vertexal angles lower than the disc, convex and with crenulate border. Clypeal border concave. Mandibles carinate, the carina impressed. Dorsal border of the antennal scrobes with a crenulate carina ending in a small denticle before the eyes. Eyes convex and not hidden by the disc. Ocelli distant from the vertexal margin.

Mesosoma flat in side view. Pronotum anteriorly sloping. Humeral angles obtuse, their sides parallel. Pronotal carina superficially marked from the sides to the center where, in some specimens, it is interrupted by a superficial furrow. Promesonotal suture impressed. Mesonotum and scutellum on the same plane and flat. Propodeum with well differentiated basal and declivous faces. Basal face converging posteriorly and bearing a pair of small, round denticles or lobes and a pair of broad, round teeth slightly directed laterally. Declivous face gently concave on the sides and converging posteriorly.

Petiole with differentiated anterior and posterior faces; anterior face sloping; posterior face short. Sides of the petiole with a pair of short, round or obtuse denticles. Postpetiole broadly convex, in some specimens with a gentle concavity in the middle. Postpetiolar sides with a pair of thick, broad, anterior lobes bearing an obtuse denticle posteriorly.

Gaster oval, with a broad, protruding anterolateral lobe.

Hind femora neither angulate nor denticulate. Hind basitarsi more compressed apically than distally and without a broad base.

Sculpture. Head dorsum reticulate and covered by large foveae broader than their interspaces, or, in some specimens, contiguous each other. Frontal carinae with foveae shallower than those on the head dorsum. Sides of the head densely foveolate. Ventral part of the head with irregular foveae variably clumped and shaped as broad reticulation. Pronotum, scutellum and upper mesopleurae reticulate with superimposed dense foveae, less dense on the anterior part of the pronotum. Mesonotum, propleurae and lower mesopleurae reticulate, with superimposed sparse and shallow foveae. Basal face of the propodeum, posterior face of the petiole, postpetiole reticulate-foveolate, the foveae agglomerate and irregular in shape. Declivous face of the propodeum and metapleurae reticulate and with faint, irregular, longitudinal rugosities, the same rugosities but rarer on the pro- and mesopleurae. Gaster, anterior face of the petiole and legs reticulate. Anterior half of the first gastral tergite and sternite and extensor face of the legs with irregular, longitudinal, anastomosing rugulosities which may or may not cover most of the first tergite. Gaster with sparse, small, piligerous foveae. Posterior half of the first gastral sternite and remaining sternites faintly reticulate and shining.

Pilosity. Each fovea with an appressed, short sensillum auricillicum. Legs and gaster apparently with the same appressed hairs as those in the foveae but thinner. Body with sparse, short, thin, suberect, truncate hairs, these hairs are very evident on each crenulation of the frontal carinae and on the sides of the body. Posterior borders of the gastral tergites and whole sternites with the same type of hairs as those on the crenulation of the frontal carinae but longer; rare, long and pointed hairs on the posterior border of the sternites.

Colour. Dark ferrugineous to light brown. Frontal carinae, sides of the head over the eyes, pronotal sides and extensor face of the tibiae yellowish-orange to light ferrugineous; remaining parts of the legs ferrugineous with darker tarsi. Gaster with two pairs of oval yellow spots, the first pair anterolateral, reaching the stigma, the second one on the posterolateral third of the gaster but not reaching the border of the tergite. Body opaque with superficially shining head.

Measurements (in mm) and indices: TL 8.08-8.22; HL 1.48-1.52; HW 1.50-1.56; EL 0.34-0.36; PW 1.48-1.52; PeW 0.64-0.67; PpW 0.77; HBaL 0.43-0.45; HBaW 0.14-0.15; CI 101.3-102.6; PI 101.3-102.6; PPeI 220.9-237.5; PPpI 192.2-197.4; HBaI 32.5-33.3.

Type Material
de Andrade and Baroni Urbani (1999) - Worker and soldier. Type locality: Viedna (Rio Negro, Argentina). Type material: 4 syntypes (one soldier and three workers) in (examined); one syntype worker in  (examined); several workers and soldiers from the same nest as the type in the collection of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (Kempf, 1958 a), not available for the present study.