Brachymyrmex sosai

This species was collected from sandy soil, from below a rock.

Identification
Ortiz-Sepulveda et al. (2019) - Brachymyrmex sosai does not have a specific unique feature but rather a unique combination of features that render it distinct: its scapes surpass the posterior margin of the head by a length approximately equal to the maximal diameter of the eye, the dorsum of the mesosoma does not have conspicuous sculpture, a metanotal groove is present, the metathoracic spiracles are in dorsal position, and the dorsal margin of the mesonotum is strongly anteroposteriorly inclined. Some features of this species are reminiscent of Brachymyrmex antennatus; however, B. sosai differs from this species in body color, the color of the hairs, the length of the scapes, and in having an antennal funiculus with the second segment shorter than the first.

The single specimen of B. sosai known from Bolivia (: USNMENT00759024) differs in color from the specimens from Peru: its head and thorax are more yellowish than brown and the gaster is darker than the rest of the body. We consider it to be part of B. sosai as all other traits match. Currently, B. sosai is only known from three localities, and more specimens from additional localities will be required to characterize the intraspecific variation in body color.

Distribution based on Regional Taxon Lists
Neotropical Region: Bolivia, Peru.

Nomenclature

 * . Brachymyrmex sosai Ortiz-Sepúlveda, et al. 2019: 529, fig. 51 (supplementary material fig. S37) (w.q.) PERU, BOLIVIA.

Worker
Holotype HL1 0.57; HL2 0.35; HL3 0.16; HW 0.53; SL 0.59; EL 0.14; WL 0.68; PnL 0.21; PnW 0.33; ML 0.16; MW 0.21; Indices CI 93.10; SI1 111.11; SI2 166.67; OI1 25.93; OI2 27.59. Paratypes (n – 3) HL10.60–0.62; HL2 0.41– 0.43; HL3 0.16–0.20; HW 0.57–0.60; SL 0.59–0.62; EL 0.14– 0.16; WL 0.68–0.72; PnL 0.20–0.23; PnW 0.41; ML 0.18– 0.20; MW 0.14–0.27; Indices CI 93.55–96.88; SI1 103.23– 103.45; SI2 142.86–145.45; OI1 22.58–27.59; OI2 25.81– 31.25.

Head. Slightly longer than wide in full face view; posterior cephalic margin flat or slightly concave. Dorsum of the head with scattered 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 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 that exceeds the maximal diameter of the eye. Ocelli typically appear to be absent but some workers have a central ocellus. Eyes are positioned on the cephalic midline and have 9–10 ommatidia along their maximal diameter.

Mesosoma. With several semi-erect hairs on the pronotum and scattered decumbent hairs on the promesonotum. The mesonotum is slightly inflated, antero-posteriorly inclined, and it bulges dorsally above the pronotum in lateral view. Metanotal groove present and wider than the diameter of the metathoracic spiracles. Metathoracic spiracles in fully dorsal position, not protruding, and not touching any sutures. Dorsum of the propodeum weakly convex and shorter than the propodeal slope. Propodeal spiracles circular, positioned slightly ventral of the posterior propodeal margin; they are posterior of the middle of the propodeal slope. Legs with appressed hairs. Petiole short and inclined forward.

Gaster. With dense pubescence and scattered long hairs at the edges of the segments.

Color and sculpture. Body smooth and shiny, and usually dark brown, but with conspicuously lighter hairs. Additionally, the bulbi of the antennae, the terminal funiculus, the tarsi, and the articulations of the legs are conspicuously yellowish.

Type Material
Holotype worker (:USNMENT00757760) and paratype workers (UNMSM: USNMENT00759061, 00759062): 3 workers, (: USNMENT01128655, 01128760): two workers, one vial (USNM: USNMENT00526429): 15 workers, five pupae, five larvae, one vial in Biorepository (USNM: USNMENT01414589): five workers, (USNMENT01128762): one queen. PERU: Cusco: Paucartambo, Kcosñipata, Predio Los Wayqechas, ACCA [Asociacion para la Conservacion de la Cuenca Amazonica], -13.17956 -71.60556, 2825 m, Andean Forest, J. Sosa-Calvo, JSC040920–04.

Etymology
In honor of Dr. Jeffrey Sosa-Calvo, the collector, for his unconditional support and friendship.

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