Brachymyrmex modestus

The type material of B. modestus was collected in association with termites (Santschi 1923b).

Identification
Ortiz-Sepulveda et al. (2019) - Santschi (1923b) mentioned the presence of physogastric workers in B. modestus, and we also observed some physogastric individuals in other samples (: MZSP138, 149). These specimens are characterized by having a larger body in comparison to regular workers, and they have shorter scapes that barely reach the posterior margin of the head.

Brachymyrmex modestus morphologically resembles Brachymyrmex donisthorpei and Brachymyrmex myops because these species have short dense hairs on the head and the mesosoma, short suberect hairs on the scapes, eyes below the cephalic midline of the head, the metanotal groove is either absent or narrower than the diameter of the metathoracic spiracles, their gaster bears dense pubescence, and their bodies are yellowish. Brachymyrmex modestus differs from B. donisthorpei by having scapes that surpass the posterior margin of the head, and from B. myops by having a mesonotum that bulges dorsally above the pronotum in lateral view.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Colombia, Ecuador.

Worker
There are physogastric workers present in a few B. modestus collections (see images of worker below). it is not known if this is indicative of all or only some colonies.

Nomenclature

 * . Brachymyrmex modestus Santschi, 1923c: 271 (w.) BRAZIL (Santa Catarina).
 * Status as species: Emery, 1925b: 43; Borgmeier, 1927c: 142; Kempf, 1972a: 40; Bolton, 1995b: 82; Fernández & Ortiz-Sepúlveda, 2019: 728; Ortiz-Sepúlveda, et al. 2019: 512 (redescription).

Worker
Ortiz-Sepulveda et al. (2019) - Lectotype and paralectotypes (n = 3) HL1 0.49–0.51; HL2 n.a.; HL3 0.14–0.16; HW 0.45; SL 0.43; EL 0.08–0.09; WL 0.49–0.55; PnL 0.10–0.14; PnW 0.29– 0.39; ML 0.08–0.16; MW 0.20–0.25; Indices CI 88.46– 92.00; SI1 95.65; SI2 n.a.; OI1 17.39–19.57; OI2 20.00–25.27. Additional material (n = 3). HL1 0.41–0.46; HL2 0.29–0.32; HL3 0.11–0.12; HW 0.38–0.45; SL 0.38–0.40; EL 0.06–0.07; WL 0.45–0.49; PnL 0.12– 0.13; PnW 0.22–0.28; ML 0.10–0.12; MW 0.18–0.22; Indices CI 91.49–100.00; SI1 90.00–97.78; SI2 120.00–133.33; OI1 15.56–18.61; OI2 23.53–27.66.

Head. Slightly longer than wide in full face view; posterior cephalic margin flat. Dorsum of the head with appresed and several suberect 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 approximately equal to the maximal diameter of the eye and bear decumbent hairs. Ocelli appear to be absent. Eyes are positioned below the cephalic midline and have 3–4 ommatidia along their maximal diameter.

Mesosoma. Usually with two erect hairs on the pronotum and two on the mesonotum; sometimes additional decumbent hairs are present, mainly on the pronotum. The mesonotum is inflated, somewhat anteriorly inclined, and bulges dorsally above the pronotum in lateral view. Metanotal groove usually absent or narrower than the diameter of the metathoracic spiracles. Metathoracic spiracles small and in dorsolateral position, not protruding, and touching the proprodeal suture. Dorsum of the propodeum convex and shorter than the propodeal slope. Propodeal spiracles circular and positioned on the posterior propodeal margin, ventrally and slightly posterior of the middle of the propodeal slope. Legs with appressed hairs. Petiole short and inclined forward.

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

Color and sculpture. Head and gaster smooth and shiny, dorsum of the mesosoma slightly imbricate. Body yellowish, with the gaster sometimes being darker in color.

Type Material
Ortiz-Sepulveda et al. (2019) - Lectotype worker (: USNMENT00758099) and paralectotype workers (NHMB: USNMENT00758099, 00758100; here designated): three workers [examined]. BRAZIL: Santa Catarina: Blumerau, A. Reinchensperguer leg.

The here designated lectotype is the specimen without expanded gaster on pin NHMB: USNMENT00758099, whereas the other specimen is one of the paralectotypes.

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
 * Rosa da Silva R. 1999. Formigas (Hymenoptera: Formicidae) do oeste de Santa Catarina: historico das coletas e lista atualizada das especies do Estado de Santa Catarina. Biotemas 12(2): 75-100.
 * Santschi F. 1923. Solenopsis et autres fourmis néotropicales. Revue Suisse de Zoologie 30: 245-273.