Brachymyrmex tristis

Nothing is known about the biology of .

Identification
Ortiz-Sepulveda et al. (2019) - Brachymyrmex tristis morphologically resembles Brachymyrmex degener and Brachymyrmex coactus (and may be conspecific; see nomenclature section below), because all three species have scapes that surpass the posterior margin of the head, they have faint sculpture on the mesosoma, their mesonotum bulges dorsally above the pronotum in lateral view, their metanotal groove is wider than the diameter of the metathoracic spiracles, the metathoracic spiracles slightly protrude, and the gaster has sparse pubescence. Brachymyrmex tristis differs from B. coactus by having a uniform body color and dense decumbent hairs on the head. It differs from B. degener by having many decumbent hairs on the head.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia.

Nomenclature

 * . Brachymyrmex tristis Mayr, 1870a: 389 (w.) COLOMBIA (“New Granada”).
 * Status as species: Dalla Torre, 1893: 174; Forel, 1899c: 123; Santschi, 1923b: 673; Emery, 1925b: 43; Kempf, 1970b: 340; Kempf, 1972a: 41; Bolton, 1995b: 82; Fernández & Ortiz-Sepúlveda, 2019: 729; Ortiz-Sepúlveda, et al. 2019: 532 (redescription).

Ortiz-Sepulveda et al. (2019) - Brachymyrmex tristis, Brachymyrmex degener and Brachymyrmex coactus are very similar morphologically (see identification section above). Further study is needed to assess whether these species are distinct or conspecific. At present, we follow previous authors in maintaining them as separate species.

Worker
Ortiz-Sepulveda et al. (2019) - Lectotype worker HL1 0.61; HL2 0.38; HL3 0.15; HW 0.56; SL 0.61; EL 0.15; WL 0.70; PnL 0.17; PnW 0.39; ML 0.17; MW 0.30; Indices CI 92.50; SI1108.11; SI2 160.00; OI1 27.03; OI2 25.00.

Head. Slightly longer than wide in full face view; posterior cephalic margin slightly concave. Dorsum of the head with dense decumbent pubescence. 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 markedly 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 up to 1.5× the maximal diameter of the eye; they have appressed hairs. Three ocelli are present. Eyes are positioned on the cephalic midline and have 10–12 ommatidia along their maximal diameter.

Mesosoma. With two erect hairs on the pronotum and usually also two on the mesonotum. The mesonotum is slightly inflated and bulges dorsally above the pronotum in lateral view. Metanotal groove wider than the diameter of the metathoracic spiracles. Metathoracic spiracles in dorsolateral position, slightly protruding, and not touching any sutures. Dorsum of the propodeum slightly convex and shorter than propodeal slope. Propodeal spiracles circular, positioned ventral of the posterior propodeal margin, at the middle of the propodeal slope. Legs with appressed hairs. Petiole short and inclined forward.

Gaster. With scattered pubescence and several scattered long erect hairs.

Color and sculpture. Head and gaster are smooth and shiny, whereas the mesosoma has faint sculpture; body uniformly dark brown apart from the tarsi of the legs which are lighter in color.

Type Material
Ortiz-Sepulveda et al. (2019) - Lectotype worker (: ANTWEB CASENT0915737; here designated): one worker [examined]. COLOMBIA: Santafé de Bogotá.

References based on Global Ant Biodiversity Informatics

 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * 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
 * Santschi F. 1923. Revue des fourmis du genre Brachymyrmex Mayr. Anales del Museo Nacional de Historia Natural de Buenos Aires 31: 650-678.