Megalomyrmex reina Longino

Longino, John T., 2010, A taxonomic review of the ant genus Megalomyrmex Forel (Hymenoptera: Formicidae) in Central America, Zootaxa 2720, pp. 35-58 : 53-54

Megalomyrmex reina Longino , new species

( Fig. 11 A–D)

Type material. Holotype queen. COSTA RICA, Alajuela: Rio Peñas Blancas, 10°19'N 84°43'W, 800 m, 2 Mar 2004 (J. Longino#5278-s) [ MCZ, unique specimen identifier JTLC 000005356]. Paratype queen: same as holotype except 4 Mar 2008 (J. Longino#6182.2) [ CAS, JTLC 000007217].

Geographic range. Costa Rica.

Diagnosis. Mandible with large apical tooth and 5–6 smaller basal teeth; dorsal surface of mandible striate; ventral margin of petiole with large translucent longitudinal flange, ventral margin of flange erose, with irregular jagged posteriorly-directed teeth; ventral margin of postpetiole with large, acute anteroventral tooth.

Description. Queen. Measurements (holotype): HW 0.833, HL 0.872, SL 0.926, EL 0.276, ML 1.519, CI 96, SI 106.

Measurements (paratype): HW 0.853, HL 0.874, SL 0.928, EL 0.294, ML 1.579, CI 98, SI 106.

Palp formula 3,2; mandible with large apical tooth and 5–6 smaller basal teeth that gradually decrease in size (holotype has 5 basal teeth on one mandible, 6 on the other); dorsal surface of mandible faintly striate; anterior clypeal margin smoothly rounded; occipital carina thin, not visible in full-face view, anterior ends extending about 1/3 to 1/2 length of ventral surface of head; face, clypeus, and ventral surface of head smooth and shiny, with a few small rugulae on clypeus beneath frontal lobes and laterally, irregular rugulae on malar space between eye and mandibular insertion, and a few concentric rugae around antennal fossa, piligerous puncta very small, resulting in overall smooth and highly polished appearance; mesosoma smooth and shiny throughout, with longitudinal carinae on metapleuron and a few longitudinal carinae over metapleural gland; notauli fused and barely visible on anterior mesonotum; parapsidal lines distinct, extending about half length of mesonotum; dorsal and posterior faces of propodeum more or less flat, meeting at a low boss; foraminal carina incomplete, curving from metapleural lobes onto posterior face of propodeum but nearly effaced medially; petiole and postpetiole smooth and shining; petiole with short posterior peduncle; ventral margin of petiole with large translucent longitudinal flange, ventral margin of flange erose, with irregular jagged posteriorly-directed teeth (detail of margin varies between holotype and paratype); ventral margin of postpetiole with large, acute anteroventral tooth; gaster smooth and shining; all dorsal body surfaces and appendages with abundant moderately coarse setae; color dark red brown.

Biology. Both queens were collected in the same locality, in mature montane wet forest. The holotype queen was in a Winkler sample of sifted leaf litter. The paratype queen was collected as a forager on the ground. The foraging queen had rapid wasp-like behavior, with rapidly vibrating antennae.

Etymology. The name of this species refers to the fact that it is known only from queens. It is a noun in apposition and invariant.

Comments. The lack of associated workers, in spite of abundant collecting (including many Winkler samples) at the type locality, raises the possibility that this species is a workerless social parasite. Alternatively, workers may be subterranean associates of attines and thus not acccessible to standard collection techniques.

The mandibular dentition of reina is highly distinctive and unlike any other Megalomyrmex species. In other species the dentition varies from a condition of few teeth that gradually decrease in size basally to one in which the two apical teeth are much larger than a series of diminished basal denticles. In contrast, reina has a single large apical tooth, which is long and sharp, followed by a relatively uniform series of smaller teeth. The size difference between the apical and subapical tooth is much greater than in other species. Many socially parasitic ant species have falcate mandibles associated with their ability to attack and subdue hosts. Perhaps the long apical tooth of reina is such an adaptation, strengthening the conjecture that it may be a social parasite.

Figures

FIGURE 11. Megalomyrmex reina. A. Holotype queen, face view. B. Same, lateral view. C. Mandible. D. Petiole and postpetiole, lateral view. Scale bar on face view = 0.5 mm, on lateral view = 1.0 mm.