Simopelta vieirai

The foragers of the type series formed a column on the forest floor. One worker was extracted from ridge top leaf litter.

Identification
Mackay and Mackay (2008) - The worker of this species is nearly identical to that of Simopelta williamsi. It differs in having the sides and top of the petiole nearly without sculpture, glossy and shining. The sides of the petiole of S. williamsi are horizontally striated, and the dorsum is granulated, usually with a longitudinal depression in the middle, the latter longitudinal depression is lacking in workers of S. vieirai. The petiolar node is nearly circular (seen from above) in S. vieirai, not angulate posteriorly as in S. williamsi. Actually, the shape of the petiolar node, as well as the smooth sculpture on the node, would separate this species from all of the others that have transverse striae on their heads.

Key to Simopelta

Distribution based on Regional Taxon Lists
Neotropical Region: Ecuador.

Habitat
High elevation montane cloud forest at 1350 - 2000 m.

Castes
Known only from the worker caste.

Nomenclature

 *  vieirai. Simopelta vieirai Mackay & Mackay, 2008: 323, figs. 13, 60-62 (w.) ECUADOR.

Worker
The worker is a moderately sized (total length 4.5 mm), dark reddish-brown ant with brown legs. The mandibles have three equal sized teeth, in which the second and third teeth are usually truncated. Head length ranges from 1.04-1.06 mm, head width 0.79-0.83 mm. The anterior border of the clypeus is broadly convex and somewhat angulate, and slightly overhangs the apron of the clypeus. The eye is moderate in size (maximum diameter 0.07 mm), located about two diameters from the anterior edge of the head. The scape (1.06-1.11 mm) extends between three or four funicular segments past the posterior lateral corner. The sides of the head become wider anteriorly, and the posterior border is nearly straight. The mesosoma is strongly concave at the metanotal suture, and the metanotum is approximately as long as the dorsal face of the propodeum. The anterior and posterior faces of the petiole are nearly straight, and the dorsal face is broadly convex. The spiracular horns are moderately developed, but the subpetiolar process is poorly developed.

Long (up to 0.2 mm), erect hairs are present on the clypeus, ventral surface of the head, scattered on the mesosoma, and on the ventral surface of the gaster, much shorter (0.02 mm) suberect to decumbent hairs are present on the dorsum of the head, dorsum of the mesosoma, dorsum of the petiole, and dorsum of the gaster, the hairs on the legs are similar, but slightly longer (up to 0.06 mm).

The head has well defined, transverse striae, which pass ventrally and anteriorly to the underside of the head and are nearly vertical between frontal lobes and the eyes. The dorsum of the mesosoma has transverse striae, the side has oblique striae. The side of the petiole is very finely striated, the dorsum of the petiole is nearly without sculpture. The gaster is nearly smooth and glossy, with faint, coriaceous sculpture.

Type Material
Holotype worker, 11 paralectotype workers (, , QCAZ, , , , ).

Etymology
Named in honor of our friend Juan Vieira, of Quito, Ecuador, who collected the type series.