Simopelta quadridentata

Specimens were found foraging on the ground in rainforest.

Identification
Longino currently (2013) considers this species to be a variant of Simopelta andersoni

Mackay and Mackay (2008) - This species could be confused with Simopelta transversa, as well as other similar species. It can be easily separated by the four mandibular teeth (mandibles have three teeth in S. transversa, and the other, related species). Among the species with four mandibular teeth, it can be separated from Simopelta laticeps, Simopelta mayri and Simopelta curvata, by the lack of the median tooth on the anterior border of the clypeus. Separation from Simopelta andersoni is difficult, but it differs in having a smaller eye (the maximum diameter of the eye of andersoni is > 0.1 mm), and the hairs on the scape are appressed against the surface (slightly elevated in S. andersoni). See the discussion of S. andersoni for more characteristics that can be used to separate these two species.

Key to Simopelta

Distribution
Puntarenas and Guanacaste, Costa Rica.

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

Castes
Known only from the worker caste.

Nomenclature

 *  quadridentata. Simopelta quadridentata Mackay & Mackay, 2008: 319, figs. 26, 55 (w.) COSTA RICA.

Worker
The mandibles have four teeth, which are approximately equal in length. The head length ranges from 0.98-1.00 mm, the head width from 0.73-0.78 mm. The clypeal apron is concave, the anterior margin of the clypeus is convex and angulate, but does not form a spine, the eye is relatively small (maximum diameter 0.07-0.09 mm) as compared with S. andersoni , located about two diameters from the anterior margin of the head. The scape is relatively long (0.96-1.00 mm) and extends about the first 2 funicular segments past the posterior lateral margin of the head. The anterior margin of the mesonotum (Weber’s length 1.57-1.58 mm) is at a noticeably lower level than the posterior border of the pronotum, the dorsum of the mesosoma is broadly concave. The anterior and posterior faces of the petiole are approximately parallel, and form a distinct, horizontal, dorsal face. The spiracular horns are well developed, and the subpetiolar process is large and basically triangular shaped, without a concave posterior face.

Erect hairs are sparse on most surfaces, except for the clypeus, the ventral surface of the head, and the ventral surface of the gaster. Most other hairs on the head, mesosoma, petiole, and gaster are decumbent to appressed, including the hairs on the tibiae.

The head is covered with transverse rugae or striae, which pass anteriorly on the sides and ventral surface of the head. The rugae or striae on the dorsum of the mesosoma are finer than those on the head, and less well defined, especially on the dorsum of pronotum. The sculpture forms concave, curved, concentric rugae on the side of the pronotum, the striae on the mesopleuron and propodeum are obliquely vertical. The petiole is encircled with striae, the apex of the node has transverse rugae. The gaster is smooth and glossy. The ant is dark reddish-brown to black.

Type Material
Holotype worker, 1 paratype worker , CR Puntarenas: 4 km SSE San Vito, 8°47’N 82°58’W [?], 1200m, 27-iii-1990, P. S. Ward # 10662-1.

Etymology
From Latin, quattuor for four and dentatus meaning toothed, referring to the four teeth of the mandible.