Simopelta species groups

The information below is based on Mackay, W.P., Mackay, E.E. 2008. Revision of the ants of the genus Simopelta Mann (pp. 285-328). In Jíminez, E., Fernández, F., Arias, T.M. & Lozano-Zambrano, F.H. (eds). Sistematica, biogeografia y conservación de las hormigas cazadoras de Colombia: 609 pp. Instituto Alexander von Humboldt, Bogota.

curvata species complex

The workers in this species complex are mostly small, with the total length usually being less than 4 mm (S. mayri is larger). The anterior medial border of the clypeus nearly always has an elongated spine or at least forms a sharp point. The dorsum of the mesosoma is slightly depressed, and the petiole is narrow.

Simopelta bicolor, a southeastern Brasilian species, can be recognized, as the mandibles have more than four teeth, and the two apicalmost teeth are not noticeably separated from the other teeth. Simopelta minima is a tiny (Total Length 2.5 mm), southeastern Brasilian species. The other three species, S. curvata, S. mayri, and S. pergandei are larger (total length usually over 3 mm) and are found in Central America and South America. Simopelta mayri (Colombia) is larger (total length greater than 4 mm) and dark brown. Simopelta curvata (SE Brasil) is smaller (TL 3.5 mm) and has four mandibular teeth. Simopelta pergandei (Central and northern South America) is smaller (TL ~ 3 mm), medium brown, and has three mandibular teeth.

williamsi species complex

The workers of these ants are relatively large (total length approximately 4-5 mm). The anterior medial margin of the clypeus may be rounded, or slightly angulate, and may even have a spine. The mesosoma is broadly and strongly depressed between the pronotum and the propodeum, when viewed in profile. The petiole is relatively thick, when viewed in profile, and with the dorsal face sloping downwardly anteriorly.

Three of the species (S. breviscapa, S. fernandezi, and S. longinoda) have a relatively short mesosoma, with the length of the mesonotum being about 2/3 of the length of the dorsal face of the propodeum. The petiolar node (seen from above) is longer than broad, and noticeably narrowed anteriorly.

Simopelta longinoda from Costa Rica can be separated from the others by the relatively smooth and glossy dorsal face of the petiole. The node of the petiole of the southern Colombian Simopelta fernandezi, and Panamanian S. breviscapa is roughly sculptured. The short antennal scapes, which barely extend past the posterior lateral corners of the head, separate S. breviscapa from S. fernandezi (caution, S. longinoda also has short antennal scapes). The antennal scapes of S. fernandezi extend at least the first funicular segment past the posterior lateral corner.

The other species have a longer mesosoma, with the mesonotum being about the same length as the dorsal face of the propodeum. Two of these species are mostly smooth and shining. Of these, S. manni from northern Ecuador has coarse, dense punctures on at least the posterior part of the head; S. laevigata (Colombia) has only a few scattered, fine punctures in the same position. All of the other species are roughly sculptured, including the head.

Simopelta jeckylli (Ecuador and Brasil) has tiny, insignificant eyes, which are much smaller in diameter than punctures on the head; the other species all have larger, noticeable eyes (but still small). Simopelta oculata from Costa Rica has relatively large eyes (diameter 0.1 mm), and a coarsely and densely punctated head, S. paeminosa (Costa Rica and Panamá) has either a granulated head or the head is covered with poorly defined, longitudinal striae, and the dorsum of the postpetiole (first gastral tergum) is covered with coarse punctures. The remainder of the species have transverse striae on at least the posterior part of the dorsum of the head.

One of the remaining species in this complex, the Costa Rican S. pentadentata, has five mandibular teeth. Three of the species (S. laticeps, S. andersoni and S. quadridentata) have four mandibular teeth. Of these three, only S. laticeps (SW Colombia and N Perú) has a medial spine on the clypeus. Of the remaining two Costa Rican species, S. andersoni has a relatively large eye (diameter 0.1 mm), S. quadridentata has a smaller eye.

Of the four remaining species (S. transversa, S. longirostris, S. vieirai, and S. williamsi), only one, the Colombian S. transversa, has long, suberect or erect hairs on the posterior tibia, some of which are as long as the greatest diameter of the tibia. The other three species have much shorter hairs, which are nearly appressed to the surface. The medial clypeal process of the southern Colombian and Ecuadorian S. longirostris is greatly elongated, and extends well past the remainder of the clypeus as a narrow lobe; the medial border of the clypeus in the other two species is broadly rounded. The sides and top of the petiole (seen from above) of S. vieirai from Colombia and Ecuador is barely sculptured, and mostly smooth and glossy, the same surfaces of S. williamsi are roughly sculptured with striae.