Leptomyrmex relictus

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Biology
Biology. Although males of L. relictus have been collected as far back as 1956 – remaining unidentified for over half a century – workers were only recently discovered in 2013 from nest samples of Cornitermes silvestrii Emerson and in 2012 from epigaeic and arboreal pitfall traps in typical cerrado (Brazilian savannah) habitat. It is unknown whether workers are nocturnal or diurnal, but hypothetical nocturnal habits and/or their Camponotus-like habitus may account for the low encounter rate of this species. It is interesting to note that at least three of the specimens were captured in arboreal pitfall traps, suggesting that workers may forage both on the soil and in the vegetation strata. The collection of workers (Fig. 1A, E) and brood (Figure S1) inside termitaria suggests that L. relictus may live in association with Cornitermes silvestrii. One termite nest measuring 1.30 m wide and about 40–50 cm tall inhabited by L. relictus was found in northeast Goiás state under a tree, and was also occupied by another ant species, Camponotus blandus (Smith, F.), which is known to be a facultative termite inquiline (Gallego-Ropero & Feitosa, 2014). The other termite nest with L. relictus specimens was found in southeast Tocantins state, along a trail edge. Unfortunately, no data are available on how the Leptomyrmex occupy the termitaria or if they were sharing galleries with the termites. A potential association with C. silvestrii is compelling as the termitaria of C. silvestrii are large, environmentally-stable clay mounds and may house several other ant and termite species. In addition to describing and comparing the sociometric and sociogenic patterns (Tschinkel, 1991, 2011) of L. relictus with the Australian species, future studies should test the association of the species with C. silvestrii.

Nomenclature

 *  relictus. Leptomyrmex relictus Boudinot, Probst et al. 2016: 663, figs. 1-5, S1, S2 (w.m.) BRAZIL.

Description
Diagnosis. With diagnostic characters of genus from Shattuck (1992), notably with medial hypostomal notch (synapomorphy of genus) and lacking pterostigmal appendage in male (synapomorphy of macro-Leptomyrmex). Distinguished from all Leptomyrmex by the following characters: (i) short, thick, erect setae present on the head capsule, mesosoma (legs included) and metasoma (Figs 1A, 3A, B); (ii) clypeal setae comparatively more numerous (Figs 1E, 3B); (iii) anterior clypeal margin strongly convex (Figs 1E, 3B); (iv) lateral hypostoma weakly flanged; (v) worker with convexity subtending subapical mandibular tooth (Fig. 1E); (vi) worker petiole lateromedially narrow; (vii) worker gaster strongly lateromedially compressed; (viii) male scape elongate (SI 1.26–1.40 versus 0.19–1.05 in other Leptomyrmex); (ix) male wing with five closed cells (costal, basal, subbasal, submarginal 1, marginal 1) (Fig. 5E); (x) male petiole dorsal margin concave (Fig. 3A); (xi) male petiolar spiracles situated on tubercles (Fig. 3A); (xii) several features of male genitalia (Fig. 3C–K; see Appendix S2 for description). Characters 1–5, 9–11 and those of 12 are unique in the genus.