Pseudomyrmex cretus

Little is known about the biology of this species.

Identification
See the nomenclature section.

Distribution
Known from Costa Rica and Guatemala.

This taxon was described from Costa Rica.

Biology
Ward (1989) - The available records suggest that P. cretus is an inhabitant of tropical dry forest. Colonies have been collected in dead twigs of Gliricidia sepium and Schoepfia sp. at the type locality (Santa Rosa National Park, Costa Rica). At the same locality workers were observed foraging on low vegetation and visiting extrafloral nectaries of Croton. Workers collected at Estrella, Costa Rica (J. Longino leg.) appeared to be nesting in a dead fence post.

Nomenclature

 *  cretus. Pseudomyrmex cretus Ward, 1989: 412, figs. 9, 26, 27 (w.q.) COSTA RICA.

The combination of large size (HW > 0.84) and petiole shape (node longer than high, broadly rounded in lateral view) separates P. cretus from all other species except Pseudomyrmex curacaensis. P. cretus and P. curacaensis appear to be sister species; their males both possess unusually lengthened palpal segments and shortened antennal segments, conditions not known to occur in other members of the P. oculatus group.

The worker of P. cretus averages larger in size than that of P. curacaensis, and in the region of size overlap (HW 0.85-0.90) it possesses a broader head, shorter eyes, and longer scapes). The two species have not been collected sympatrically, P. cretus being known from Guatemala and Costa Rica, P. curacaensis from Panama and most of South America. It is possible that intermediate populations will be located in Central America, and the name P. cretus would then become a junior subjective synonym of P. curacaensis, but the Panama collections of P. curacaensis which I have examined do not approach P. cretus in size or head shape.

Worker
Measurements (n=14). —HL 0.99-1.22, HW 0.85-0.98, MFC 0.027-0.035, CI 0.78-0.86, OI 0.57-0.60, REL 0.49-0.53, REL2 0.62-0.65, OOI 0.07-0.35, VI 0.74-0.81, FCI 0.028-0.039, SI 0.46-0.50, SI2 0.73-0.80, FI 0.40-0.46, POI 1.21-1.43, MPI 0.047-0.068, NI 0.60-0.65, PLI 0.77-0.89, PWI 0.69-0.78, PPWI 1.21-1.50.

Worker Diagnosis. —A relatively large species for the P. oculatus group (HW 0.85-0.98), with broad head, long scapes, and relatively short eyes (SI2 0.73-0.80); sides of head broadly convex, occipital margin weakly concave in frontal view; second and third funicular segments as long as, or longer than, wide (FLI 1.94-2.40, n=5). Fore femur relatively slender; metanotal groove conspicuous but not sharply excavated; basal face of propodeum flat to weakly convex, raised slightly above the level of the mesonotum, longer than the declivitous face from which it is usually well differentiated; juncture of basal and declivitous faces of propodeum often marked laterally by a slight angle, which continues as weak margination flanking the flat declivitous face. Petiole apendunculate with a well-developed anteroventral process, the node high and broadly rounded in lateral view, rather broad in dorsal view (see petiolar indices); lateral margination of petiolar node more marked than in most other species of the oculatus group; postpetiole notably broader than long.

Mandibles striato-punctate; head densely punctate, subopaque, upper third becoming sublucid due to shiny interspaces between the punctures (which are separated by 0.25 to 1.0 their diameters); mesosoma punctate to coriarious-imbricate, the mesonotum and centre and sides of pronotum sublucid, remainder mostly opaque. Petiole, postpetiole, and gaster sublucid, the lustre subdued by numerous fine piligerous punctures and associated pubescence. Fine erect pilosity and appressed pubescence common on most of the body, including mesosoma dorsum; the pilosity a little longer and denser than is typical for the oculatus group. Light to medium castaneous brown, the gaster and femora darker brown (variably so), with varying degrees of modest infuscation of the mesosoma; mandibles paler, luteous brown.

Type Material
Holotype worker. —COSTA RICA, Provo Guanacaste: Santa Rosa Natl. Park, 300m, 10°51'N, 85°37'W, 14.xii.1983, ex dead twig of Schoepfia, tropical dry forest, P. S. Ward acc. no. 6434. HW 0.95, HL 1.18, EL 0.61, PL 0.52, PH 0.42.

Paratypes. —Same locality and date as holotype, P. S. Ward acc. nos. 6434 and 6427-2: two series of workers; COSTA RICA, Provo Guanacaste: Santa Rosa Natl. Park, 270m, l0°50'N, 85°38'W, 14.xii.1983, P. S. Ward acc. nos. 6443, 6444, 6446, and 6448, workers and dealate queens. (,, , , MCZC, , , , , , , )