Pseudomyrmex rubiginosus

The type specimens were collected from Triplaris, and there are additional records of colonies inhabiting Triplaris, Pleurothyrium poeppigii Nees, Gustavia, Ocotea, and Tachigali cf. formicarum. It is the only Pseudomyrmex plant-ant that has been found inhabiting both Triplaris and Tachigali. (Ward 1999)

Identification
Ward (1999) - P. rubiginosus can be recognized by the bicoloured body and by the somewhat angular profile to the worker propodeum and petiole, although there is some variation in the shape of both these structures. Nevertheless, differentiated anterior and dorsal faces of the petiole can be discerned in lateral view, and the dorsal face rounds suddenly into the steep posterior face. Other useful identifying characteristics are the head shape (worker CI 0.84–0.91, queen CI ≈ 0.78), patterns of standing pilosity in the worker (see above), and relatively long petiole (worker PL/LHT 0.52–0.58, queen PL/LHT ≈ 0.70).

Distribution
Known from Brazil, Colombia and Peru.

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

Nomenclature

 *  rubiginosus. Pseudomyrma sericea var. rubiginosa Stitz, 1913: 211 (w.) BRAZIL. Combination in Pseudomyrmex: Kempf, 1972a: 223. Raised to species and senior synonym of huberi: Ward, 1999b: 525.
 * huberi. Pseudomyrma sericea var. huberi Santschi, 1922b: 346 (w.) BRAZIL. Combination in Pseudomyrmex: Kempf, 1972a: 223. Junior synonym of rubiginosus: Ward, 1999b: 525.

Worker
Ward (1999) - Measurements (n=10). HL 1.18–1.37, HW 1.01–1.19, MFC 0.035–0.046, LHT 0.77–0.95, CI 0.84–0.91, REL 0.56–0.61, REL2 0.65–0.69, FCI 0.03–0.04, FI 0.44–0.49, PLI 0.86–1.02, PWI 0.81–0.95.

A member of the sericeus group. Palp formula: variable (6,4 or 5,3). Frontal carinae relatively well separated; head only moderately elongate, sides weakly convex; posterior margin of head concave, in frontal view. Profemur moderately broad; legs relatively short (LHT/HL 0.65–0.71). Dorsal face of Propodeum subequal in length to declivitous face, and usually rounding rather suddenly into it; propodeal spiracle distant from basal (dorsal) face of propodeum. Petiole relatively long and broad, subtrapezoidal in profile, with weakly differentiated anterior and dorsal faces, and dorsal face rounding relatively suddenly into vertical posterior face. Anteroventral process moderately well developed, a triangular or rounded lobe, typically without a well-marked posteroventral tooth or angle (but exceptions occur). Standing pilosity sparse; a single pair of stout, paired golden setae rather consistently present on the propodeum at the junction of the basal and declivitous faces, on the petiole, and on the postpetiole; pilosity more variable on the pronotum (1–2 pairs) and mesonotum (0–1 pair); occasionally additional short hairs present on these surfaces. Bicoloured, with head mostly dark grey-brown, gaster medium-brown, and remainder of body, including mandibles, antennae, frontoclypeal complex and legs, dusky yellow- or orange-brown; variable amounts of infuscation on the mesosoma (especially posteriorly), petiole, postpetiole and legs.

Type Material
Ward (1999) - Syntype workers, “Brasilien” [Alto Acre, Brazil] (Ule) [Examined].

Pseudomyrma sericea var. huberi. Syntype workers, Rio Puru[s], Amazonas, Brazil (Huber) [Examined].

References based on Global Ant Biodiversity Informatics

 * Palacio G., E.E. and F. Fernandez. 1995. Hormigas de Colombia V: Neuvos registros. Tacaya 4:6-7