Brachymyrmex micromegas

The type-series was collected near the locality where the Independência Park arboretum is now located, just beside the MZSP building in Ipiranga, São Paulo, Brazil. Despite recent field trips to the locality, none specimens have been collected (R.M. Feitosa, pers. comm., in Ortiz & Fernández, 2014).

Identification
This species can be differentiated from most other Brachymyrmex species by the following: presence of tumuliform metathoracic spiracles (see key for image of this character); worker caste dimorphic; toruli touching the posterior clypeal margin, but never surpassing it (best observed in anterodorsal oblique view); and clypeus with a row of long thick hairs near the anterior margin. These traits are shared with Brachymyrmex pilipes, but B. micromegas differs from B. pilipes by smooth and shiny body, with very fine longitudinal striations restricted to the metapleura; the body color is usually light brown. (Ortiz & Fernández, 2014).

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Castes
Only known from the worker castes. This species has major and minor workers, which is unusual for the genus.

Nomenclature

 * . Brachymyrmex (Bryscha) micromegas Emery, in Santschi, 1923b: 675, figs. 30, 32 (w) BRAZIL (São Paulo).
 * Status as species: Luederwaldt, 1918: 48; Emery, 1925b: 44; Borgmeier, 1927c: 142; Kempf, 1972a: 41; Bolton, 1995b: 82; Ortiz, C.M. & Fernández, 2014: 16 (redescription); Ortiz-Sepúlveda, et al. 2019: 508 (redescription).

Worker
Ortiz & Fernández (2014) - Minor Lectotype measurements (mm) (n=1) HL1 0.78; HL2 0.49; HL3 0.29; HW 0.70; SL 0.72; EL 0.21; WL 0.98; PnL 0.29; PnW 0.53; ML 0.23; MW 0.53; Indices CI 90; SI1 102.77; SI2 148; OI 30.55. Paralectotype measurements (mm) HL1 0.78; HL2 0.49; HL3 0.29; HW 0.70; SL 0.72; EL 0.21; WL 0.98; PnL 0.29; PnW 0.53; ML 0.23; MW 0.53; Indices CI 90; SI1 102.77; SI2 148; OI 30.55. Additional material examined measurements (mm) (n=2) HL1 0.83 – 0.94; HL2 0.25 – 0.33; HW 0.77 – 0.86; SL 0.74 – 0.80; EL 0.16 – 0.19; WL 1.0 – 1.10; PnL 0.29 – 0.33; PnW 0.53 – 0.59; ML 0.23 – 0.27; MW 0.25 – 0.33; Indices CI 92 – 94; SI1 92 – 97; SI2 71 – 76; OI 21 – 22.

Head longer than wide, sub-rectangular. Posterior cephalic border slightly concave. Clypeus large, with rounded anterior margin. Toruli touching the posterior clypeal margin but never surpassing it (best observed in anterodorsal oblique view). Scapes long, surpassing the posterior margin of the head. Ocelli present. Eyes well developed, situated posterior to mid line of head, with 14–15 ommatidia at maximum diameter. Promesonotum in profile conspicuously convex, higher than propodeum. Mesonotum inclined, strongly convex, in profile and separated from pronotum.

Metanotal groove deep, wide. Metathoracic spiracles fully dorsal, tumuliform, bulging out of the metanotal groove in lateral view. Propodeal spiracle near to declivity of propodeum. Petiolar scale not inclined forward.

Body smooth and shiny, except for the metapleura, which have very fine, longitudinal striations. Most of mandibular surface smooth and shiny (best observed in anterodorsal oblique view). Entire body, including antennae, legs and palps with conspicuous erect and sub-erect pilosity. Clypeus with a row of many long thick hairs near the anterior margin, the rest of the clypeal surface with many shorter hairs. Gaster smooth and shiny without scattered long erect hairs and without dense pubescence. Body usually light brown, gaster often darker.

Major Paralectotype measurements (mm) (n=3). HL1 1.66 – 1.88; HL2 1.17; HL3 0.57 – 0.63; HW 1.66 – 1.83; SL 1.12 – 1.23; EL 0.25 – 0.28; WL 1.66 – 1.8; PnL 0.49 – 0.73; PnW 1.05 – 1.13; ML 0.55 – 0.63; MW 0.63 – 0.75; Indices CI 95 – 100; SI1 61.6 – 74.12; SI2 105; OI 15.1 – 15.7.

Head strongly cordate, broader at eye level. Clypeus large, with anterior margin rounded. Toruli touching the posterior clypeal margin but never surpassing it. Scapes surpassing the posterior margin of the head. Ocelli present. Eyes well developed, situated posterior to the midline of the head. Promesonotum in profile strongly convex, higher than the propodeum.

Metanotal groove deep. Metathoracic spiracles fully dorsal, tumuliform, bulging out of the metanotal groove in lateral view. Propodeal spiracle near to declivity of propodeum. Petiole scale not inclined forward, rounded.

Body smooth and shiny, except for the metapleura, which has very fine, longitudinal striations. The entire body, including antennae, legs and palps with conspicuous, erect and sub-erect pilosity. Clypeus with a row of many long thick hairs near anterior margin, the rest of the clypeal surface shiny and with many shorter hairs. Body light brown.

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 C. M., and F. Fernández. 2014. Brachymyrmex species with tumuliform metathoracic spiracles: description of three new species and discussion of dimorphism in the genus (Hymenoptera, Formicidae). ZooKeys 371: 13-33.
 * 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.
 * Suguituru S. S., D. R. de Souza, C. de Bortoli Munhae, R. Pacheco, and M. S. de Castro Morini. 2011. Diversidade e riqueza de formigas (Hymenoptera: Formicidae) em remanescentes de Mata Atlântica na Bacia Hidrográfica do Alto Tietê, SP. Biota Neotrop. 13(2): 141-152.
 * Suguituru S. S., M. Santina de Castro Morini, R. M. Feitosa, and R. Rosa da Silva. 2015. Formigas do Alto Tiete. Canal 6 Editora 458 pages
 * Suguituru S. S., R. Rosa Silva, D. R. de Souza, C. de Bortoli Munhae, and M. Santina de Castro Morini. Ant community richness and composition across a gradient from Eucalyptus plantations to secondary Atlantic Forest. Biota Neotrop. 11(1): 369-376.