Leptogenys rabebe

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

Leptogenys rabebe casent0034619 p 1 high.jpg

Leptogenys rabebe casent0034619 d 1 high.jpg

Specimen Labels

It nests in rotten logs and forages mainly in leaf litter.

Identification

Rakotonirina and Fisher (2014) - Worker. Mandible not closing tightly against clypeus at rest; eye small with maximum diameter less than greatest width of antennal scape; antennal scape short, extending beyond posterior cephalic margin by one-fifth of its apical portion.

Leptogenys rabebe can be confused with species in the toeraniva group but is easily differentiated by the discontinuous lamellate membrane on the lateral and anteromedian lobes of the clypeus, leaving a gap between the sides of the anteromedian lobe of the clypeus and mandibles when the latter are fully closed. Its prora is located near the anteroventral angle of third abdominal sternite. In the toeraniva group, the mandibles are capable of closing tightly against the clypeus and there is usually a large indentation between the prora and the rounded anteroventral angle of third abdominal sternite. Leptogenys rabebe closely resembles the species in the incisa group but these latter species have larger eyes whose maximum diameter is markedly greater than the maximum width of antennal scape and the mandible is more arched from the base to the apex.

Keys including this Species

Distribution

This species is restricted to the northeast of Madagascar and has been collected from the transitional humid forest of Marotandrano near Mandritsara, the lowland rainforest of Ambatovaky, and the Montagne d’Akirindro of Makira.

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.

  • rabebe. Leptogenys rabebe Rakotonirina & Fisher, 2014: 159, figs. 40A, 129, 178 (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

(3 specimens). HW: 0.95–1.00, HL: 1.22–1.24, CI: 77–82, SL: 1.03–1.10, SI: 102–115, PW: 0.79–0.80, WL: 1.79–1.82, PNH: 0.72–0.73, PNL: 0.48–0.54, PNW: 0.64–0.69, DNI: 119–143, LNI: 134–152.

Head longer than broad, widest at level of eyes, with slightly convex lateral border. Eye small, maximum diameter about half of greatest width of scape. Antennal scape relatively short, only about one-fifth of its length surpassing posterior cephalic margin. Anterior clypeal margin with narrow triangular median lobe, bordered with thin, semi-translucent lamella; lateral portion narrow and bordered by broad lamellate membrane; three peg-like setae projecting anteriorly from anterior margin of median lobe. Mandibles elongate and linear, not closing tightly against margin of clypeus when their apices cross one another; basal groove distinctly impressed. With mesosoma in dorsal view, metanotal groove impressed and transversely striate. In lateral view, petiolar node slightly higher than broad, with straight anterior and posterior faces and fairly convex dorsal margin. Subpetiolar process consisting of toothlike extension anteriorly followed by rounded lobe posteriorly, with indentation between them. In lateral view, helcium located approximately at mid-height of anterior margin of third abdominal segment; prora large and lobe-like; anteroventral angle of third abdominal sternite usually rounded. Prora and anteroventral angle of third abdominal sternite not separated by wide indentation. Constriction between third and fourth abdominal segments absent or very weakly visible. Sculpture of head dorsum rugulose-punctate or reticulate punctate anteriorly, becoming punctate posteriorly. In dorsal view, pronotum and petiolar node mostly smooth and shining, with scattered superficial punctures; mesonotum, propodeum, and third and fourth abdominal tergites shallowly punctate. Mesopleuron and metapleuron densely and finely rugose. Color dark brown to reddish-orange with brown or lighter appendages.

Type Material

Holotype worker: Madagascar, Toamasina, RS Ambatovaky, Sandrangato river, -16.8175, 49.295, 360 m, rainforest, ex rotten log, 25 Feb 2010 (B.L. Fisher et al.) collection code: BLF24761, specimen code: CASENT0163120 (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.