Brachymyrmex gaucho

Nothing is known about the biology of .

Identification
Ortiz-Sepulveda et al. (2019) - Brachymyrmex gaucho is morphologically similar to Brachymyrmex antennatus because both have legs and antennae with erect hairs and a second segment of the antennal funiculus that is as long as or longer than the first. However, B. gaucho differs from B. antennatus by having a flat posterior cephalic margin, a dark brown body, erect hairs on the scape, and the dorsum of the head, a mesonotum that bulges dorsally above the pronotum, and a gaster with scarce pubescence.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina.

Nomenclature

 * . Brachymyrmex gaucho Santschi, 1917f: 283 (w.) ARGENTINA (Córdoba).
 * Combination in Brachymyrmex (Bryscha): Santschi, 1923b: 674.
 * Status as species: Santschi, 1923b: 674; Emery, 1925b: 44; Kempf, 1972a: 41; Bolton, 1995b: 82; Quirán, 2005: 767 (redescription); Ortiz-Sepúlveda, et al. 2019: 500 (redescription).

Worker
Ortiz-Sepulveda et al. (2019) - Head. Almost equally wide as long in full face view; the posterior cephalic margin is flat and the posterior side of the head is wider than the anterior side. Dorsum of the head bears scattered erect 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 decumbent. Toruli surpassing the posterior clypeal margin in oblique anterodorsal view. The scapes surpass the posterior cephalic margin by a length smaller than 1.5× the maximal diameter of the eye and have erect hairs. The second segment of the antennal funiculus is as long as or longer than the first. Three ocelli are present. Eyes are positioned on the cephalic midline and have 13–14 ommatidia along their maximal diameter.

Mesosoma. With several thin, erect hairs. The mesonotum is inflated, anteroposteriorly inclined and bulges dorsally above the pronotum in lateral view. Metanotal groove usually absent, but when present narrower than the diameter of the metathoracic spiracles. Metathoracic spiracles in dorsolateral position, slightly protruding, and near the propodeal suture. Dorsum of the propodeum flat and equal in length to the propodeal slope. Propodeal spiracles circular, positioned just dorsally of the posterior propodeal margin and slightly posterior of the middle of the propodeal slope. Legs have suberect and erect 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 dorsum of the mesosoma is imbricate. Body uniformly dark brown.

Type Material
Ortiz-Sepulveda et al. (2019) - Brachymyrmex gaucho Santschi, 1917: 283 (w.). [examined, but the type is severely damaged]. ARGENTINA: Córdoba: Unquillo, M. Birabén.

The type specimen in the NHMB is damaged but Quirán deposited three workers belonging to this species from Argentina, Córdoba II-2001, E. Quirán, leg. at the NHMB, which we also examined. These specimens come from the same state as the type material, but they are no types. More type material would exist at the (5 workers) and the MLP (1 worker) (Quirán 2005), but it is not studied here.

References based on Global Ant Biodiversity Informatics

 * Cuezzo, F. 1998. Formicidae. Chapter 42 in Morrone J.J., and S. Coscaron (dirs) Biodiversidad de artropodos argentinos: una perspectiva biotaxonomica Ediciones Sur, La Plata. Pages 452-462.
 * 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
 * Quiran E. 2005. El género neotropical Brachymyrmex Mayr (Hymenoptera: Formicidae) en la Argentina. II: redescripción de las especies B. admotus Mayr, de B. brevicornis emery y B. gaucho Santschi. Neotrop. Entomol. 34(5): 761-768.