Leptogenys avaratra

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

Leptogenys avaratra casent0041949 p 1 high.jpg

Leptogenys avaratra casent0041949 d 1 high.jpg

Specimen Labels

This species is only known from the dry forest habitats of Montagne des Francais in the north and the transitional humid forests of Antshabe near Daraina in the northeast of Madagascar. This rare species nests in rotten logs and forages through leaf litter.

Identification

A member of the toeraniva species group. Rakotonirina and Fisher (2014) - Worker. Mandible capable of closing tightly against clypeus; maximum diameter of eye less than greatest width of scape. In full-face view head subquadrate (CI: 78–82); in profile, helcium located very low near the anteroventral angle of third abdominal segment; prora voluminous and anteroventral section of third abdominal sternite rounded; indentation weakly visible between prora and anteroventral angle.

Worker specimens of L. avaratra are very similar to other species within the toeraniva species group, but can be separated by the square form of the petiolar node in dorsal view, and the location of the prora near the anteroventral angle of the third abdominal segment. In the other species in this group, the petiolar node is approximately as high as long in profile, and the prora is separated from the rounded anteroventral angle of third abdominal sternite by an indentation. This species has been found from two different sites. Specimens from the two sites differ in the extent and depth of the sculpture.

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.

  • avaratra. Leptogenys avaratra Rakotonirina & Fisher, 2014: 131, figs. 3A, 3B, 150, 155 (w.q.) MADAGASCAR.

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

Description

Worker

(4 specimens). HW: 0.91–0.99, HL: 1.17–1.21, CI: 78–82, SL: 1.22–1.29, SI: 130–133, PW: 0.77–0.82, WL: 1.76–1.90, PNH: 0.65–0.70, PNL: 0.63–0.68, PNW: 0.58–0.66, DNI: 90–99, LNI: 102–107.

Head subquadrate, lateral margins nearly straight and joining posterior margin in convex line. Maximum eye diameter about half the greatest width of scape. Clypeus with convex lateral lobes which converge abruptly into narrow anteromedian lobe; lobe covered with semi-translucent lamella. Mandible short and narrow, inner margin convex at about apical third of length; blades capable of closing tightly against clypeus. Scape long, roughly one-third of its length extending beyond posterior cephalic margin. In dorsal view, metanotal groove visible but not cross-ribbed. With petiole in dorsal view, node roughly as long as broad; in profile node as broad as high, with vertically straight anterior and posterior faces, both of which round into broadly convex dorsal face. Helcium located at lower level near anteroventral angle of third abdominal segment. Prora relatively voluminous and anteroventral portion of third abdominal sternite rounded; prora and anteroventral section not separated by strong indentation. Constriction between third and fourth abdominal segments indistinct. Dorsum of head with sparse, shallow punctures. Dorsal surface of mesosoma, petiolar node, and abdominal tergites III and IV sparsely punctulate to punctate; elongate punctures sometimes present, with fairly effaced, fine rugulae. In profile, mesopleuron and lower lateral surface of propodeum and petiolar node reticulate-rugose; propodeal declivity transversely rugulose. Integument reddish brown, appendages and tip of gaster ferruginous-red.

Queen

HW: 0.90, HL: 1.12, CI: 80, SL: 1.10, SI: 121, PW: 0.72, WL: 1.64, PNH: 0.55, PNL: 0.55, PNW: 0.60, DNI: 109, LNI: 100.

Ergatoid queen looks very similar to worker due to its lack of ocelli, but differs by the short and broadly convex dorsal outline of the mesosoma, the anteroposteriorly flattened petiolar node and a much larger gaster.

Type Material

Holotype worker: Madagascar, Antsiranana, Montagne des Français, 7.2 km 142° SE Antsiranana (= Diego Suarez), -12.3228, 49.3382, 180 m, tropical dry forest, ex rotten log, 22–28 Feb 2001 (Fisher, Griswold et al.) collection code: BLF03177, specimen code: CASENT0416208 (California Academy of Sciences). Paratypes: 1 ergatoid queen and 4 workers, with same data as holotype but with the following specimen codes: CASENT0416209 (ergatoid queen), CASENT0416210, CASENT0247238, CASENT0247239, CASENT0247240 (CASC, The Natural History Museum, Musee d'Histoire Naturelle Genève, 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.