Leptogenys arcirostris

Worker specimens of L. arcirostris look for prey on the surface of the forest floor and in leaf litter, and their colonies are mostly found in rotten logs and under rocks.

Identification
A member of the arcirostris complex of the truncatirostris species group. Rakotonirina and Fisher (2014) - Worker. Clypeus with median carina, width when measured from anterior level of torulus to anteromedian margin of clypeus less than or equal to maximum diameter of scape; in full-face view head longer than broad, antennal scape relatively short; few short suberect hairs and abundant pubescence present on dorsum of head, mesosoma and gaster.

Leptogenys arcirostris is closely related to Leptogenys borivava and Leptogenys alatapia but in L. borivava, the body size is smaller (HW: 0.97–1.01, WL: 1.77–1.87), and the dorsum of the head, mesosoma, petiole, and gaster is with reduced pubescence and covered with long standing erect and suberect hairs. The head is much broader (CI: 105–109) in L. alatapia.

Distribution
Recent surveys of ants across Madagascar have found this species only in the southern part of the island. It ranges from the montane rainforests of Atsirakambiaty near Itremo and Anja Reserve to the gallery forests of the PN Isalo and Mitea Forest, through the spiny forests/thickets of the PN Tsimanampetsotsa and the dry forest habitats of Vohidava near Amboasary. However, the type locality of L. arcirostris is Moramanga, in central-eastern Madagascar. Leptogenys arcirostris can survive in a wide range of habitats and may have had a larger geographic range, extending to Moramanga, in the recent past. Anthropogenic disturbance and deforestation may have caused local extinction in the northern part of its range.

Distribution based on Regional Taxon Lists
Malagasy Region: Madagascar.

Nomenclature

 *  arcirostris. Leptogenys (Machaerogenys) arcirostris Santschi, 1926a: 25 (w.) MADAGASCAR. See also: Bolton, 1975a: 295.

Worker
Rakotonirina and Fisher (2014) - (10 specimens). HW: 1.18–1.38, HL: 1.27–1.43, CI: 93–97, SL: 1.32–1.46, SI: 103–112, PW: 0.72–0.95, WL: 2.08–2.32, PNH: 0.68–0.74, PNL: 0.53–0.62, PNW: 0.60–0.68, DNI: 107–115, LNI: 119–133.

Head broader in front than behind, the sides more or less straight, diverging anteriorly and rounding in a convex line with a straight posterior margin. Eye large, not breaking the lateral cephalic border. Antennal scape relatively short (SI: 103–112). In full-face view, clypeus with broad and evenly rounded anterior margin, fringed by wide, white-yellowish membrane; median lobe short, width when measured from anterior level of torulus to anteromedian margin of clypeus less than or equal to maximum diameter of scape; medial longitudinal carina present. With head in full-face view and mandible fully closed, blades superimposed on one another, with internal surface of first blade tightly closed against clypeus along their length and that of the second blade against external face of the first. In dorsal view, metanotal groove transversely striate; in lateral view, propodeal lobe bluntly angular. With petiole in profile, anterior face of node vertically straight, posterior face convex, both forming rounded angles with dorsal margin. Mandible longitudinally striate, interspersed with piligerous punctures. Dorsum of head, pronotum and petiolar node densely and finely reticulate-punctate, punctures becoming smaller near posterior margin of head. Rest of dorsum of mesosoma finely reticulate-rugose. Mesopleuron and lower part of propodeum reticulate-rugulose, with scattered large punctures. Propodeal declivity transversely rugulose. Third abdominal tergite densely and finely reticulate-rugose to finely reticulate-punctate. Standing short hairs few; pubescence quite abundant on dorsum of head and rest of body. Color black to dark brown; base of appendages brown, their apices and tip of gaster lighter in color.

Type Material
Rakotonirina and Fisher (2014) - Holotype worker, Madagascar, Moramanga (Descarpentries) AntWeb specimen code: CASENT0101132 [examined].

References based on Global Ant Biodiversity Informatics

 * Bolton B. 1975. A revision of the ant genus Leptogenys Roger (Hymenoptera: Formicidae) in the Ethiopian region with a review of the Malagasy species. Bulletin of the British Museum (Natural History). Entomology 31: 235-305.
 * Fisher B. L. 1997. Biogeography and ecology of the ant fauna of Madagascar (Hymenoptera: Formicidae). Journal of Natural History 31: 269-302.
 * Fisher B. L. 2003. Formicidae, ants. Pp. 811-819 in: Goodman, S. M.; Benstead, J. P. (eds.) 2003. The natural history of Madagascar. Chicago: University of Chicago Press, xxi + 1709 pp.
 * Rakotonirina J. C., and B. L. Fisher. 2014. Revision of the Malagasy ponerine ants of the genus Leptogenys Roger (Hymenoptera: Formicidae). Zootaxa 3836 (1): 001163.