Pseudomyrmex caeciliae

A twig nesting species that is found in a wide range of habitats and vegetation.

Identification
See the nomenclature section.

Identification Keys including this Taxon

 * Key to US Pseudomyrmex species

Distribution
Texas to Panama

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Costa Rica, Greater Antilles, Guatemala, Honduras, Mexico, Nicaragua, Panama.

It is also found in Mexico and the United States.

Biology
Ward (1989) - P. caeciliae has been collected nesting in dead twigs of Quercus and Prosopis in Texas and northern Mexico. Costa Rican nest-site records include dead twigs of Gliricidia sepium, Anacardium and Laguncularia racemosa. Habitat records cover a broad range (tropical dry forest, mangrove, littoral vegetation, riparian forest, edge of second-growth rain forest, rain forest) but suggest a preference for open areas. In Costa Rica the species is notably less common than Pseudomyrmex elongatus.

Nomenclature

 *  caeciliae. Pseudomyrma eduardi r. caeciliae Forel, 1913l: 214 (w.) GUATEMALA. Combination in Pseudomyrmex: Kempf, 1972a: 217. Raised to species: Ward, 1989: 410.

Ward (1989) - The characteristic features of P. caeciliae are its small size, relatively dark color, and the sublucid punctate appearance of parts of the head and mesosoma. It is distinguished from Pseudomyrmex elongatus primarily on the basis of this shiny appearance (all of their metric measurements overlap broadly, although P. elongatus averages larger in size, with relatively longer eyes - compare HW, HL and REL). Typically P. elongatus workers have a densely punctate and opaque head, while in P. caeciliae the punctures on the head are less dense, with (correspondingly) more extensive shiny interspaces between them, especially in the area immediately posterior to the compound eye; but both species vary considerably, and the extremes of sculptural variation come close to overlapping.

Among material examined in the present study, an old series of workers from Escuintla, Guatemala (Wheeler leg.) included both P. elongatus, P. caeciliae, and several individuals seemingly intermediate between the two. In western Mexico (Jalisco, Sinaloa), where P. caeciliae is apparently absent, some P. elongatus workers approach P. caeciliae in head sculpture. On the other hand in Costa Rica, where the two species are broadly sympatric, I have seen no intermediates among material referable to the two species.

P. caeciliae differs from Pseudomyrmex cubaensis by its smaller size (HW <0.62), relatively longer eyes (REL2 0.72-0.81), broader fore femur, and shorter petiole. While Mexican and Central American populations of these two species are rather distinct, Jamaican "caeciliae" partly bridge the gap between the two. These Jamaican individuals may, in fact, represent small P. cubaensis.

The relationship of P. caeciliae to the South American species, Pseudomyrmex urbanus, is even more problematic. The existing differences between the two are slight (see key to species) and not wholly diagnostic. More material, especially worker-associated queens and males from northern South America, will be needed to resolve this issue.

Worker
Ward (1989) - measurements (n=26). —HL 0.73-0.91, HW 0.51 -0.61, MFC 0.012-0.023, CI 0.67-0.74, OI 0.52-0.60, REL 0.48-0.55, REL2 0.72-0.81, OOI 0.22-0.80, VI 0.73-0.91, FCI 0.021-0.041, SI 0.42-0.49, SI2 0.55-0.63, FI 0.45-0.51, POI 0.91-1.45, MPI 0.048-0.084, NI 0.55-0.63, PLI 0.79-0.91, PWI 0.61-0.74, PPWI 1.09-1.39.

diagnosis. Small species (HW 0.51-0.61) with elongate eyes (REL2 0.72-0.81); ocelli relatively well-separated, OD/HW > 0.127; sides of head subparallel, rounding into the occipital margin, the latter flat to weakly concave, in full-face view; second and third funicular segments broader than long, usually notably so (FLI 1.23-1.72, n=5). Fore femur relatively broad; metanotal groove well marked; basal face of propodeum flat to weakly convex, often raised perceptibly above the level of the mesonotum; basal face rounding into declivitous face of propodeum, to which it is subequal or slightly greater in length (see POI values). Petiole relatively short and high (PLI > 0.79), with an anteroventral process, variously developed; postpetiole of typical dimensions, broader than long.

Mandibles striate (sometimes weakly so), with scattered punctures. Head densely punctate, the punctures separated by shiny interspaces at least on parts of the upper third of the head, and especially in the area immediately posterior to the compound eye, so that these parts of the head appear sublucid to shiny (in contrast to the predominantly opaque head of P. elongatus); head punctures relatively coarse, 0.010 to 0.020 mm in diameter; mesosoma punctate to coriarious-imbricate, sublucid in the centre of the pronotal and mesonotal discs, and on the side of the pronotum, more opaque elsewhere; petiole, postpetiole, and gaster sublucid, with numerous fine piligerous punctures. Fine, erect pilosity (sometimes rather short) and appressed pubescence common over most of the body, including the mesosoma dorsum. Body medium to dark brown in color, the mandibles, antennae, and tarsi varying from concolorous to a paler luteous brown.

Type Material
Ward (1989) - Two syntype workers, Patulul, Guatemala (Peper) [Examined]. One worker here designated LECTOTYPE.