Tranopelta

Ground dwelling ants (soil, litter and downed wood) that have mostly been collected in litter samples. Little is known about the biology of the two species in this genus. Tranopelta gilva appears to be much more common than the rarely collected Tranopelta subterranea hence more is know about the former.

Identification
Fernández (2003) - Tranopelta shows a moderate type of polymorphism with “minor” and “major” workers that may differ in some characteristics, mainly in the head. Major worker with palps 4.3 (Ettershank 1966).

The following combination of characters distinguishes Tranopelta from any other ant genera: Antennae with 11 segments and a 3-segmented club, mandibles with 4 to 5 teeth, propodeum lacks teeth or angles, petiole with ventrally bifurcated carinae, postpetiole with anterior ventral process, and moderate polymorphism.

Species identification:

Workers
 * Promesonotum and propodeum each strongly convex in side view, clearly split by a deep metanotal groove; scapes approaching or slightly surpassing the vertexal border; Ecudar, Brazil, Bolivia . . . . . Tranopelta subterranea
 * Promesonotum and propodeum continuous in side view (Fig. 2A0; scapes ending before the vertexal border; Costa Rica to Brazil . . . . . Tranopelta gilva

Queens
 * Scape of antennae surpassing the vertexal border; eyes < 0.50 mm in length . . . . . Tranopelta subterranea
 * Scape of antennae not surpassing in the vertexal border; eyes > 0.50 mm in length . . . . . Tranopelta gilva

Males
 * Eyes closer to posterior clypeal margin than to ocellus; mandibles crossing when closed (Fig. 3G) . . . . . Tranopelta subterranea
 * Eyes equidistant between ocelli and clypeal margin; mandibles never touching (Fig. 2G) . . . . . Tranopelta gilva

Species richness
Species richness by country based on regional taxon lists (countries with darker colours are more species-rich). View Data



Nomenclature

 *  TRANOPELTA [Myrmicinae: Solenopsidini]
 * Tranopelta Mayr, 1866a: 512. Type-species: Tranopelta gilva, by monotypy.

Fernández (2003):

Worker
[modified from Ettershank, 1966: 107): Worker. Length between 2 and nearly 6 mm. Slightly polymorphic, with simple continuous allometry leading to large-headed workers. Mandibles with four to five teeth. Canthellus of mandible just meeting the basal margin, trulleum distinct and closed. Labrum cleft, distal edge of lobes straight or rounded. Palpal formula 3.2: 4,3 in major workers of T. subterranea. Eyes poorly to moderately developed, with 3 to nearly 30 facets. Antennae 11-segmented with 3-segmented club. Head without antennal scrobes. Mesosoma with promesonotum and propodeum continuous in side view, only broken by clearly defined metanotal groove. Propodeum rounded, without spines, propodeal spiracles round, large, conspicuous. Bulla of metapleural gland bulging, with dorsal margin approaching propodeal spiracle. Propodeal spiracle ovoid to round, partly constricted in the larger workers. Petiole with differentiated peduncle and node. Petiolar spiracle situated midway between propodeal lobes and node. Petiole with dentiform ventral process, sometimes developed as a narrow spine. Posterior end of petiole with sides forming distinct carinae converging in middle of the posteroventral face. Postpetiole with distinct anterior ventral process: more or less broadly attached to gaster. Workers smooth to finely sculptured, sparsely to moderately hairy.

Queen
Larger than workers, around 12 mm in length. Antennal club scarcely differentiated. Palpal formula 4,3. Dorsal pilosity short and dense.

Male
Size: about 7 mm in length. Mandibles with 3 teeth, touching when closed. Petiole with neither subpetiolar process nor bifurcated carinae in ventral view.