Leptogenys namana

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Leptogenys namana
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Leptogenys
Species group: incisa
Species complex: imerinensis
Species: L. namana
Binomial name
Leptogenys namana
Rakotonirina & Fisher, 2014

Leptogenys namana casent0067496 p 1 high.jpg

Leptogenys namana casent0067496 d 1 high.jpg

Specimen Labels

Leptogenys namana is widespread in the humid forest habitats of eastern Madagascar, but are rarely found, particularly in the north of the island. Worker specimens were found foraging on lower vegetation, even though the colony nests were collected from rotten logs.

Identification

A member of the imerinensis complex of the incisa species group. Rakotonirina and Fisher (2014) - Worker. Anterior margin of median lobe of clypeus with two small, peg-like setae; medial clypeal carina sharp; antennal scape relatively short (SI: 115–118), less than apical third extending beyond posterior cephalic margin; in dorsal view, mesosoma consists of three visible segments, with no distinct segment between metanotal groove and propodeum; propodeal posterior margin with toothlike lobe; head dorsum densely and finely reticulate-rugose; propodeal dorsum coarsely rugose; declivity surface not distinctly delimited, side of propodeum roughly rounding to the declivity. Smaller species.

Leptogenys namana is morphologically quite variable, especially in the width of the translucent lamella, the extent of sculpture on the head, mesosoma and petiolar node, the presence of toothlike propodeal lobe, and the shape of the petiolar node. A worker specimen from the RS Marotandrano has a finely reticulate-punctate head dorsum, microreticulate propodeal dorsum superimposed with sparse punctures, and the absence of a toothlike lobe on propodeal posterior margin. Some specimens from southern Madagascar have a propodeal declivity not well delimited by posterolateral margin, with the sides of the propodeum rounding to the almost slightly convex declivitous surface.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

The Leptogenys genus page has more details about the general biology of ants in this genus. The following synopsis provided by Rakotonirina and Fisher (2014) offers an overview of the Malagasy Leptogenys: Recent surveys of arthropods in the Malagasy region uncovered a wealth of new species and showed that Leptogenys is one of the dominant ponerine ants widely distributed across all types of forest habitats. Workers are usually found foraging on the forest floor or in the leaf litter and only rarely on vegetation. They nest terrestrially under the soil, rocks, logs, or rootmat ground layers and in rotten logs, branches, in rotting bamboo, and rotten tree stumps. Most of the Malagasy species are endemic to Madagascar. In all Malagasy species, winged queens are absent, which limits their ability to disperse across the complex topography and various ecological barriers in the region. In the absence of alate queens, reproduction of Leptogenys in the region may be by fission, which enhances population viscosity and may result in important morphological variation across a species' geographic range. Though queens do not fly, males of Leptogenys are alate and are one of the most frequently collected ant genera in Malaise traps throughout Madagascar. Leptogenys exhibits a wide range of phenotypic diversity segregated both among spatially isolated habitats and along continuous environmental gradients.

Castes

Worker

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • namana. Leptogenys namana Rakotonirina & Fisher, 2014: 91, figs. 49B, 52B, 54A, 104, 120 (w.) MADAGASCAR.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

(9 specimens). HW: 1.10–1.25, HL: 1.31–1.51, CI: 78–83, SL: 1.31–1.50, SI: 118–128, PW: 0.92–1.06, WL: 2.25–2.64, PNH: 0.75–0.84, PNL: 0.71–0.83, PNW: 0.71–0.78, DNI: 91–105, LNI: 95–107.

Head in full-face view subrectangular, lateral border slightly convex and weakly diverging anteriorly. Eye large, weakly convex; in full-face view, location feebly breaking outline of lateral border of head. Antennal scape moderately short, apical fourth section approximately surpassing posterior margin of head. Clypeus with convex lateral lobes, whose margin converge anteriorly into a triangular median lobe; anteromedian lobe bordered with two peg-like setae; narrow translucent lamella broadly convex along lateral border of clypeus and angulate at anteromedian margin; median longitudinal carina of clypeus sharp. Mandible elongate and slender, fairly curved at base and inner margin slightly concave; preapical denticle present near sharp apical tooth; basal groove vestigial to faintly effaced. Hypostomal teeth visible in full-face view of head. Metanotal groove impressed; mesosoma in dorsal view consists of three segments, with no additional suture visible between metanotal groove and propodeum. In profile, mesosoma generally long and low; posterolateral margin of propodeum with toothlike lobe; declivitous surface not clearly defined, lateral surface and dorsum of propodeum joining declivity in a rounded angle. Petiolar node in profile generally as high as broad, dorsal margin convex and anterior and posterior faces weakly inclined anteriorly. In dorsal view, petiolar node longer than broad and slightly narrower in front than behind. Constriction distinctly visible between third and fourth abdominal segments. Mandible generally sparsely punctate, with a smooth and shining surface on basal portion and fine striation near apex. Sculptures of head dorsum, mesosoma and petiolar node densely and finely reticulate-punctate to densely and finely reticulate-rugose. Third abdominal tergite finely microreticulate, with scattered shallow punctures; the fourth almost smooth and shining. Erect, slender, yellowish hairs present on dorsum of body, pubescence abundant on head and appendages and reduced or lacking on rest of body dorsum. Integument black, tarsa, apex of antenna, mandible and gaster brown or light brown.

Type Material

Holotype worker: Madagascar, Fianarantsoa, PN Ranomafana, Vatoharanana River, 4.1 km 231° SW Ranomafana, -21.29, 47.4333, 1100 m, montane rainforest, beating low vegetation, 27–31 Mar 2003 (Fisher, Griswold et al.), collection code: BLF08401, specimen code: CASENT0488652 (California Academy of Sciences).

References

  • Rakotonirina, J.C. & Fisher, B.L. 2014. Revision of the Malagasy ponerine ants of the genus Leptogenys Roger (Hymenoptera: Formicidae). Zootaxa 3836, 1-163.