Acanthostichus laticornis

Mackay (1996) - One nest found under large rock, numerous workers, single female, apparently in a termite nest. A staphylinid (Aleocharinae: Paradoxenusa silvestrii Bruch) occurs with this species (Bruch, 1937). These ants forage in columns similar to Eciton, but smaller; they prey on termites (Kusnezov, 1962).

Identification
Mackay (1996) - The worker is similar to that of Acanthostichus kirbyi, but is easily distinguished by the short, thick scapes with a well formed angle (Fig. 4). The female is very similar to that of Acanthostichus quadratus, but differs in that the anterior surface of the scape is angulate and the female of this species possesses a well developed malar groove. The male is almost indistinguishable from that of A. laticornis. It differs primarily in that the sculpture of the propodeum is rougher.

Keys

 * Key to Acanthostichus workers
 * Key to Acanthostichus males

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Brazil, Paraguay, Uruguay.

Nomenclature

 *  laticornis. Acanthostichus laticornis Forel, 1908c: 345 (w.) PARAGUAY. Santschi, 1933e: 106 (m.); Mackay, 1996: 158 (q.). Senior synonym of obscuridens: Kusnezov, 1962a: 131.
 * obscuridens. Acanthostichus laticornis var. obscuridens Santschi, 1934c: 23 (w.) ARGENTINA. Bruch, 1934a: 4 (q.m.). Junior synonym of laticornis: Kusnezov, 1962a: 131.

Worker
Mackay (1996) - HL 1.01-1.31, HW 0.86-1.20, SL 0.50-0.66, SW 0.23-0.29, FL 0.70-0.95, FW 0.24-0.35, WL 1.28-1.73, PW 0.38-0.53, PL 0.46-0.65, SI 49-50, CI 85-91, PI 123-124, FI 271-295, SL/SW 2.22-2.30.

Mandibles without teeth. but with slight undulations. lateral clypeal teeth well developed; scape relatively short and thick. with well developed angle (Fig. 4); vertex concave; petiole somewhat elongate. subpetiolar process rounded anteriorly with sharp ventral apex posteriorly (Fig. 27); femur not thickened.

Queen
Mackay (1996) - HL 1.64, HW 1.82, SL 0.73, SW 0.34, EL 0.20, WL 2.20, PW 1.60, PL 0.81, SI 45, CI 111, PI 51, SL/SW 2.15.

Mandibles without teeth; lateral clypeal angles well formed; malar groove well developed. but extending only ½ distance to eye; outer margin of scape angulate as in worker; femora not incrassate; petiole much wider than long, wider at posterior end. Entire ant covered with scarce, flexuous hairs, concolorous light brown.

Male
Mackay (1996) - HL 0.74-0.95, HW (posterior to eye) 0.66-0.96, SL 0.20-0.28, EL 0.39-0.48, WL 1.66-1.68, PW 0.36-0.39, PL 0.45-0.51, SI 27-29, CI 90-101, PI 124-132.

The male is similar to those of other species in the genus and is difficult to separate. Apparently the shape of the volsellae, shape of the petiole and sculpturing of the propodeum will separate this species from some of the other species (see key). The scape is slightly thickened, but bears no resemblance to the characteristic shape of the scape of the worker.

Type Material
Mackay (1996) - Worker. PARAGUAY: San Bernardino 15 cotype workers (12 worker cotypes,, 1 worker cotype, , 2 workers, possibly cotypes, ) [all seen]. Acanthostichus laticornis, lectotype worker (here designated) (MHNG) and eleven paralectotype workers (MHNG), 1 paralectotype worker (NHMB), PARAGUAY. San Bernardino (Fiebig); A. laticornis Forel worker type Formic #5944., oll. Forel [all seen]. Two possible cotype workers in MACN. Acanthostichus laticornis var. obscuridens, ARGENTINA. Misiones. Estacion Experimental Loreto. Dr. A. A. Oglobin, 24-viii-1933, female, lectotype worker (here designated) (NHMB) and 4 paralectotype workers (NHMB) [seen], five paralectotype workers [seen].