Brachymyrmex gagates

Identification
This species seems to be quite distinct from any of those included in Santschi's monograph of Brachymyrmex (1923). It runs to Brachymyrmex incisus in his table, but typical specimens of this form from Panama in my collection show that it differs from gagates in having a narrower head, much less prominent mesonotum, indistinct and unimpressed promesonotal suture, shorter funicular joints, much paler coloration, etc. (Wheeler 1934)

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Nomenclature

 *  gagates. Brachymyrmex gagates Wheeler, W.M. 1934g: 206 (w.) MEXICO.

Description
Length 2-2.5 mm.

Head rounded subrectangular and dorsally convex as in the other species of the genus; posterior border straight, with a slight median sinuation. Eyes rather large, flattened, a little behind the middle of the sides and less than twice their length from the anterior corners. Ocelli distinct. Mandibles small, with oblique 5-toothed terminal borders, the median tooth minute. Clypeus large, convex but ecarinate in the middle, its anterior border broadly rounded and projecting, concealing the closed mandibles. Frontal area subtriangular, not very sharply defined; frontal groove represented anteriorly as an indistinct longitudinal ridge but concave just in front of the anterior ocellus. Antennal scapes extending fully one-fourth their length beyond the posterior corners of the head; second funicular joint one and one-half times as long as broad, a little more than half as long as the first joint; joints 3-7 more than one and one-half times as long as broad, terminal joint as long as the two preceding subequal joints together. Thorax with strong and distinctly impressed promesonotal suture, interrupting the dorsal outline, and deep mesoepinotal impression; metaepinotal suture distinct, the prominent metanotal spiracles small, separated by more than five times their diameter. Pronotum broad and rounded, mesonotum less than twice as broad as long, very convex, projecting above the pronotum; metaepinotum slightly longer than broad, trapezoidal, distinctly broader behind than in front; base and declivity of epinotum in profile straight and subequal, the former horizontal, the latter sloping, forming together a rounded but distinct obtuse angle. Petiolar scale small, thin and very narrow, its anterior surface concave above, its posterior surface feebly convex. Gaster voluminous, pointed posteriorly, its large first segment overlying the petiole and provided with a deep groove for its accommodation. Legs stout, fore femora distinctly enlarged and somewhat compressed.

Very shining and very finely and superficially reticulate; basal half of mandibles obscurely striatopunctate; sides of thorax less shining than the dorsal surface; metapleurae subopaque, finely and densely punctate.

Hairs reddish or brownish, pubescence whitish; the former sparse, erect and pointed, in several rows on the gastric segments, absent on the appendages. Pubescence short, distinct, appressed and dilute on the posterior portion of the head; absent on the thorax and abdomen; abundant and subappressed on the appendages, somewhat longer on the antennae than on the legs.

Jet black; clypeus, tips of mandibles and insertions of antennae red; sides of head, antennae and legs dark brown; funiculi sometimes more reddish; tarsal joints beyond the metatarsi pale yellow; trochanters and neck yellowish brown.