Brachymyrmex antennatus

Nothing is known about the biology of .

Identification
Ortiz-Sepulveda et al. (2019) – Brachymyrmex antennatus morphologically resembles Brachymyrmex gaucho, because both species have legs and antennae with suberect hairs and both have an antennal funiculus with the second segment as long as or longer than the first. However, they differ from one another because B. antennatus has abundant, suberect hairs on the dorsum of the head and mesosoma, its gaster has dense pubescence, and its body is lighter and yellowish. Brachymyrmex antennatus also resembles Brachymyrmex cavernicola in having suberect hairs on the mesosoma that are generally darker in color than the tegument, but B. antennatus has a more elongated head, a longer second segment of the antennal funiculus, as mentioned above, thinner hair on its body and denser pubescence on the gaster. Substantial variation exists in the body size of workers of B. antennatus from various locations that were studied here, and the cause of this variation remains uncertain.

Substantial variation exists in the body size of workers of B. antennatus from various locations.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Brazil, Colombia, Ecuador, French Guiana, Peru, Suriname.

Nomenclature

 * . Brachymyrmex (Bryscha) antennatus Santschi, 1929d: 312, fig. 35 (w.q.) BRAZIL (Paraná).
 * Status as species: Kempf, 1972a: 41; Bolton, 1995b: 81; Ortiz-Sepúlveda, et al. 2019: 463 (redescription).

Worker
Ortiz-Sepulveda et al. (2019) - Lectotype and paralectotype (n = 2). HL1 0.68–0.71; HL2 n.a.; HL3 0.19–0.23; HW 0.68–0.71; SL 0.68–0.80; EL 0.15; WL 0.87; PnL 0.31–0.33; PnW 0.45; ML 0.21; MW 0.27; Indices CI 95.50–95.80; SI1 100.00–123.00; SI2 n.a.; OI1 22.22–23.25; OI2 27.94–31.41. Additional material (n = 5). HL1 0.54–0.60; HL2 0.38–0.41; HL3 012–0.16; HW 0.54– 0.58; SL 0.52–0.63; EL 0.09–0.14; WL 0.60–0.71; PnL 0.15–0.22; PnW 0.35–0.40; ML 0.14–0.18; MW 0.20–0.24; Indices CI 92.31–100.00; SI1 93.33–130.23; SI2 130.23– 155.56; OI1 15.38–26.67; OI2 21.67–29.03.

Head. Longer than wide in full face view; posterior cephalic border concave. Dorsum of the head with scattered decumbent hairs. Clypeus with a rounded anterior margin and five long, erect hairs of which a single, usually conspicuous apical hair is near the anterior margin, two lateral hairs in medial position and two more near the toruli; other hairs on the clypeus are conspicuously shorter and appressed or decumbent. Toruli surpassing the posterior clypeal margin (in oblique anterodorsal view). Scapes surpass the posterior cephalic margin by a length of 1.5× the maximum eye diameter or more. The second segment of the antennal funiculus is as long as the first or longer. The scapes typically have suberect and erect hairs. Three ocelli present. Eyes are positioned on the cephalic midline and have 7–9 ommatidia along their maximal diameter.

Mesosoma. With conspicuous, thin erect hairs of darker color than the tegument. Pronotum anteroposteriorly elongated. The mesonotum is slightly antero-posteriorly inclined, weakly inflated, and it does not bulge dorsally above the pronotum in lateral view. Metanotal groove deep and wider than the diameter of the metathoracic spiracles. Metathoracic spiracles in dorsolateral position and slightly protruding, closer to the propodeal than to the mesometanotal suture, but not touching any suture. Dorsum of propodeum flat and equal in length to the propodeal slope. Propodeal spiracles circular, situated ventral of the posterior propodeal margin. Legs with suberect and erect hairs. Petiole short and inclined forward.

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

Color and sculpture. Body typically uniformly light brown, although some specimens may be light brownish with the head and gaster darker brown.

Type Material
Ortiz-Sepulveda et al. (2019) - Lectotype worker (: USNMENT00758161) and paralectotype worker, queen (NHMB: USNMENT00758161; here designated): two workers, one queen (without USNMENT number). BRAZIL: Paraná, Rio Negro.

The ant at the top of pin USNMENT00758161 is designated here as lectotype and the one immediately below as paralectotype. Santschi’s collection contains three additional pins with four workers from the same locality but they are not considered to be part of the type collection as they have no type label. Santschi (1929) described the queen from a sample that does not contain any workers but expressed confidence that it belongs to B. antennatus; the issue may require verification from independent material.

References based on Global Ant Biodiversity Informatics

 * 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