Leptogenys coerulescens

Collection data indicate that this species forages on the forest floor and on low vegetation as well as through the leaf litter. Leptogenys coerulescens nests mainly under the ground and in rotten logs, but occasionally in rotten tree stumps, under rootmat ground layers or under rocks.

Identification
One of the largest species (HW: 1.52–1.74, PW: 1.23–1.46) in the attenuata group, L. coerulescens can be recognized by its size, the location of the eye and the presence of punctures with fine striation on the mandible. Two extremes characterize the variation within this species. One extreme is represented by specimens sampled from the dry forest habitats. The dorsal outline of the propodeum in profile is slightly convex and the petiole in dorsal view is shorter and anteriorly more slender. This variant is most similar to the type specimens.The second extreme, collected from rainforest areas, is characterized by a straight propodeal dorsum, and a more elongate and anteriorly robust petiolar node. Across the range of this species, both the shape of the propodeum and the form of the petiolar node show continuous variation and transitional states. Phenotypic variants within this species occur along ecological gradients across the forest habitats of Daraina in the northeast of Madagascar and in the disjunct forests of Ambilanivy, Anabohazo, Manongarivo and Ankarana in the northwest of the island. These results illustrate the importance of recognizing habitats that harbor distinct allopatric populations and maximizing the protection of contiguous environmental gradients to maintain the viability of morphologically diverse populations.

Key to Malagasy Leptogenys

Distribution
Northern Madagascar.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Habitat
Although the distribution of L. coerulescens is limited to northern Madagascar, this species occupies a wide range of habitats including lowland and montane rainforests as well as littoral and dry forest habitats adjacent to these mesic forests.

Nomenclature

 *  coerulescens. Leptogenys coerulescens Emery, 1895f: 339 (w.) MADAGASCAR. See also: Bolton, 1975a: 296.

Worker
Rakotonirina and Fisher (2014) - (25 specimens). HW: 1.52–1.74, HL: 1.92–2.15, CI: 76–84, SL: 2.33–2.71, SI: 145–163, PW: 1.23–1.46, WL: 3.22–3.73, PNH: 1.09–1.25, PNL: 0.92–1.13, PNW: 0.86–1.06, DNI: 84–105, LNI: 100–121.

Head more or less elongate, width greatest at about mid-length immediately posterior to eye; sides distinctly convex; posterior margin straight. In full-face view, eye not breaking outline of side of head; size larger, maximum diameter roughly one-fourth the length of side of head. Antennal scape long, distal half surpassing posterior margin of head. Third antennal segment less than twice the length of second. With mesosoma in profile propodeal dorsum slightly convex; propodeal lobe absent or with blunt angle; opening of propodeal spiracle circular. In dorsal view, petiolar node more or less elongate but slightly broader posteriorly than anteriorly. With petiole in profile, node about as high as long. Mandible finely punctate, with fine and short longitudinal striation or dense elongate punctures. Declivitous surface most often smooth, rarely transversely rugulose or with striation. Remainder of body dorsum smooth and shining. Dorsum of head, mesosoma, petiolar node and gaster covered with whitish-yellow, standing short hairs and pubescence. Color black with bluish reflection or opalescence, apical portion of appendages reddish brown or ferruginous red.

Queen
Rakotonirina and Fisher (2014) - (3 specimens): HW: 1.52–1.64, HL: 1.90–1.97, CI: 80–84, SL: 2.14–2.41, SI: 141–147, PW: 1.21–1.31, WL: 3.08–3.18, PNH: 1.05–1.17, PNL: 0.75–0.82, PNW: 1.01–1.06, DNI: 124–146, LNI: 134–153. As in worker but with broader head and shorter antennal scape. No trace of ocelli. Mesosoma slightly rounded and much shorter, without wing sclerites. Hairs and pubescence more slender and abundant.

Type Material
Rakotonirina and Fisher (2014) - Lectotype worker, present designation, Madagascar, Diego-Suarez (Alluaud, 1893), AntWeb CASENT0102027 top worker specimen of two workers on a pin (MSNG). Paralectotype workers, with same data but specimen coded as CASENT0102026 and CASENT0102025 (MSNG) [examined].