Simopelta paeminosa

Workers have been collected from leaf litter. Longino - This species occurs in mature montane forest habitats, generally above 1000m elevation. I know it from the upper Peñas Blancas Valley, the 1100m site on the Barva transect in Braulio Carrillo National Park, Wilson Botanical Garden near San Vito, and the Bocas del Toro area of Panama. I also have one collection given to me by Bill Brown from Valle, Colombia. He identified it as an undescribed species, but it matches my concept of paeminosa. For one collection (JTL0863) I observed workers and brood caches in the leaf litter. The larvae were of uniform size, and closely matched the "young larva" illustrations in Wheeler and Wheeler (1986, Figs. 11b, 13a, 14c). Another collection (JTL4360) was a colony in a clump of dirt in the middle of a recent clearing in mature forest. I tried excavating it and found workers and larvae scattered in the dirt mound, but I never found a queen.

Identification
Mackay and Mackay (2008) - The relatively small eye would separate this species from Simopelta oculata and Simopelta andersoni. The granulated sculpturing of the head distinguishes it from several species, which have transverse striae or rugae (i.e. S. transversa). The three-toothed mandible separates it from the Brazilian Simopelta curvata. The dark color distinguishes it from the Brazilian Simopelta minima and the Central and South American Simopelta pergandei. The punctures on the dorsum of the postpetiole would distinguish it from all the other species. Five specimens (5 k SW of the Estación Biológica Las Cruces) differ in having finer and sparser punctures (about 6 per 0.1 mm2 versus about 10 per 0.1 mm²), as well as in having small punctures on the second gastral tergum, which are lacking in the typical S. paeminosa, and could be a new species.

Distribution
Costa Rica, Panama, Colombia.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia, Costa Rica, Panama.

Habitat
Wet montane tropical and cloud forest, 1050 - 1150m. Costa Rica: montane sites from Cordillera de Tilarán southward.

Castes
Known only from the worker caste.

Nomenclature

 *  paeminosa. Simopelta paeminosa Snelling, R.R. 1971b: 17, fig. 1 (w.) COSTA RICA. Combination in Belonopelta: Baroni Urbani, 1975b: 300; in Simopelta: Bolton, 1995b: 383. See also: Mackay & Mackay, 2008: 315.

Worker
Mackay and Mackay (2008) - These are moderate sized (total length slightly over 4 mm), dark reddish black ants, with appendages being somewhat paler. The mandible has three teeth, the basalmost tooth usually being poorly developed. The anterior border of the clypeus is broadly convex, without a spine. The eye is relatively small (0.08 mm, maximum diameter about ½ distance between anterior edge of eye and anterior edge of head). The anterior face of the petiole is broadly rounded, meeting the posterior, vertical face at a right angle.

Erect and suberect hairs are present on most surfaces, including the dorsal and ventral surfaces of the head, scape, mesosoma, petiole, gaster, the hairs on the legs are finer and suberect. The entire head, mesosoma, and petiole are granulate and dull, or with poorly defined rugae, the dorsum of the propodeum and petiole have poorly defined, transverse rugae, the dorsum of the postpetiole is covered with scattered, punctures, with the region between the punctures being smooth and glossy.