Leptogenys pilaka

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

Leptogenys pilaka casent0134025 p 1 high.jpg

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Specimen Labels

Worker specimens were found foraging on the forest floor, and the colony nests were located in the rotten logs.

Identification

A member of the alluaudi complex of the incisa species group. Rakotonirina and Fisher (2014) - Worker. Small, peg-like setae absent from near anteromedian margin of clypeus, above anteriorly fringing semi-translucent lamella; in full-face view, eye extending beyond lateral cephalic margin; head short (CI: 94–97); antennal scape relatively short; mandible narrow, inner margin not convex and slightly curved near bases; blades mostly smooth with faint longitudinal striation.

Leptogenys pilaka is very similar to Leptogenys incisa andLeptogenys alluaudi, but is separable from L. alluaudi by the location of its eyes, which split the lateral outline of the head. In L. alluaudi, the eyes do not break the lateral cephalic margin. The species can be separated from L. incisa by its broader head and by the narrower mandibular blades which are not strongly curved at the base and have a largely smooth and shiny 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

Habitat

Leptogenys pilaka occurs in northern Madagascar, in the transitional forest of the RS Ankarana at 80 m and in the lower montane rainforest of PN Montagne d’Ambre at 885 m.

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.

  • pilaka. Leptogenys pilaka Rakotonirina & Fisher, 2014: 95, figs. 46B, 47B, 106, 122 (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

(5 specimens). HW: 1.98–2.17, HL: 2.09–2.23, CI: 94–97, SL: 2.38–2.52, SI: 116–123, PW: 1.37–1.47, WL: 3.45–3.66, PNH: 1.14–1.22, PNL: 1.04–1.11, PNW: 0.97–1.09, DNI: 90–99, LNI: 106–112.

Head more or less elongate and broader anteriorly than posteriorly; lateral border weakly convex and diverging from back to front. Eye large, jutting from head surface and splitting lateral cephalic margin. Antennal scape relatively short. Lateral margin of clypeus convex and rounding to short, narrowly triangular anteromedian lobe; edge of clypeus fringed with narrow and obtusely angulate semi-translucent lamella. Mandible long and slender, weakly curved near base; inner margin concave; apical portions not strongly intersecting and not closing tightly against clypeus. Hypostomal teeth not visible when head in full-face view. In lateral view, mesosoma relatively high and short; with bluntly angulate junction between propodeal dorsum and declivity; propodeal lobe with blunt angle. In dorsal view, mesosoma with three visible segments, metanotal groove impressed. Constriction between third and fourth abdominal segments fairly visible. Mandibles are mostly smooth and shining, though sparse and short striation may be present. Dorsum of head finely longitudinally rugulose from front to level of anterior margin of eye, becoming densely and finely reticulate-rugose toward mid-length of head, rest of head dorsum with fine microreticulate rugulae superimposed with large and shallow elongate punctures. Anterior portion of pronotum finely microreticulate, superimposed with coarse punctures; rest of mesosomal dorsum and petiolar node microreticulate, overlaid by a mixture of fine and coarse transverse rugae and shallow, large elongate punctures. Declivitous surface transversely rugose. Third abdominal tergite with elongate small punctures. Standing hairs present, pubescence abundant on head dorsum but very sparse on rest of body dorsum. Coloration black, basal portion of appendages brown, apical portion and tip of gaster light brown.

Type Material

Holotype worker: Madagascar, Antsiranana, RS Ankarana, 22.9 km 224° SW Anivorano Nord, -12.9089, 49.1098, 80 m, tropical dry forest, ex rotten log, 10–16 Feb 2001 (Fisher, Griswold et al.) collection code: BLF02867, specimen code: CASENT0428200 (California Academy of Sciences). Paratypes: 4 workers with same data as holotype but with the following specimen codes: CASENT0428201, CASENT0428202, CASENT0428116, CASENT0247223 (CASC, The Natural History Museum, Parc Botanique et Zoologique de Tsimbazaza).

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.