Brachymyrmex bicolor

Specimens were collected from leaf litter in cloud forest.

Identification
Ortiz-Sepulveda et al. (2019) - The conspicuous color pattern allows distinguishing Brachymyrmex bicolor from any other Brachymyrmex species.

Distribution based on Regional Taxon Lists
Neotropical Region: Honduras.

Castes
One of the few species of Brachymyrmex with an intermediate worker-queen caste.

Nomenclature

 * . Brachymyrmex bicolor Ortiz-Sepúlveda, et al. 2019: 472, fig. 13 (supplemental material S7) (w. w-q intercaste. q.) HONDURAS.

Worker
Holotype HL1 0.43; HL2 0.30; HL3 0.10; HW 0.38; SL 0.44; EL 0.11; WL 0.48; PnL 0.12; PnW 0.28; ML 0.10; MW 0.16; Indices CI 88.78; SI1 114.94; SI2 147.06; OI1 27.59; OI2 22.45. Paratype HL1 0.43; HL2 n.a.; HL3 0.10; HW 0.41; SL 0.45; EL 0.11; WL 0.48; PnL 0.12; PnW 0.28; ML 0.11; MW 0.15; Indices CI 94.90; SI1 109.68; SI2 n.a.; OI1 25.81; OI2 22.45.

Head. Slightly longer than wide in full face view; posterior cephalic margin slightly convex. Dorsum of the head with appressed hairs. Clypeus with a rounded anterior margin and five long, erect hairs of which a single, usually conspicuous hair is near the anterior margin, two hairs are in mediolateral position, and two more near the toruli; other hairs on the clypeus are clearly shorter and appressed or decumbent. Toruli surpassing the posterior clypeal margin in oblique anterodorsal view. The scapes surpass the posterior margin of the head by a length larger than the maximal diameter of the eye and have appressed pubescence. Three conspicuous ocelli. Eyes are positioned on the cephalic midline and have eight ommatidia along their maximal diameter.

Mesosoma. Without erect hairs and in lateral view approximately hour-glass shaped (this condition is absent in the presumed intercast) with a constriction between the bulging promesonotum and propodeum. In lateral view, the mesonotum is anteriorly inclined, but it does not bulge dorsally above the pronotum. Metanotal groove present and wider than the diameter of the metathoracic spiracles. Dorsum of the propodeum is convex and shorter than the propodeal slope. Metathoracic spiracles in dorsal position, not protruding, not touching any sutures. Propodeal spiracles circular, positioned just ventrally of the posterior propodeal margin slightly posterior of the middle of the propodeal slope. Legs with appressed and scattered hairs. Petiole short and inclined forward.

Gaster. With scarce pubescence and several scattered long erect hairs at the edge of the segments.

Color and sculpture. Body smooth and shiny, with a conspicuous bicolored pattern. The head and gaster are blackish in color, however, the mandibles, the labial and maxillary palps, the bulbi and bases of the antennae, the terminal antennomeres and hairs are conspicuously yellow in color. Additionally, the mesosoma and legs are yellowish, with the tibia of the second and third pairs of legs being dark brownish, like most of the scape.

Intercaste
The presumed worker-queen intercaste differs from the worker mainly by its larger body size, the shape of the mesosoma in lateral view, and its dense pubescence on the gaster. The dorsum of the head bears two rows of erect hairs. Eyes have around ten ommatidia along their maximal diameter; the promesonotum is bluntly angular, with the mesonotum being not inflated or bulging out dorsally above the pronotum in lateral view, mesonotum in dorsal view posteriorly extended along the midline. Metanotal groove absent. Dorsum of the propodeum is flat and shorter than the length of the propodeal slope. Metathoracic spiracles in dorsolateral position, not protruding, not touching any sutures. Gaster with dense pubescence and several scattered long erect hairs at the edges of the segments.

Type Material
Holotype worker (: CASENT0615272) and Paratype worker, putative worker-queen intercastes (USNM: CASENT0615274 (putative worker-queen intercaste); CASENT0615277, 0615294, 0617077 (destroyed) (three workers), 0615292 (one queen); : CASENT0615273 (putative worker-queen intercaste), 0615276 (one worker)): five workers, one queen, two putative worker-queen intercastes. HONDURAS: Comayagua: PN Cerro Azul Meambar, 14.87092, -87.89917, 1120 m, 20 May 2010, LLAMA#Wa-C-04-1-31.

Etymology
The epithet bicolor reflects the conspicuous body coloration with black head and gaster and yellow mesosoma.

References based on Global Ant Biodiversity Informatics

 * Ortiz-Sepuvelda C. M., B. Van Bocxlaer, A. D. Meneses, and F. Fernandez. 2019. Molecular and morphological recognition of species boundaries in the neglected ant genus Brachymyrmex (Hymenoptera: Formicidae): toward a taxonomic revision. Organisms Diversity & Evolution https://doi.org/10.1007/s13127-019-00406-2