Allomerus septemarticulatus

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Allomerus septemarticulatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Allomerus
Species: A. septemarticulatus
Binomial name
Allomerus septemarticulatus
Mayr, 1878

Allomerus septemarticulatus casent0902177 p 1 high.jpg

Allomerus septemarticulatus casent0902177 d 1 high.jpg

Specimen Labels

Wheeler reported (1942) on specimens from "Amazonas, in leaf sacs of Duroia saccifera Spruce; Sao Joaquim, Rio Negro, Amazonas, in leaf sacs of Duroia saccifera Spruce.


Fernández (2007) - Types from this species were not examined. Wheeler (1942:203) stated that the A. septemarticulatus female is “smaller and paler” than that of Allomerus octoarticulatus. The studied female matches in this aspect, that is why this material is probably conspecific with that studied by Mayr in the original description.

If the interpretation above is correct, A. septemarticulatus is not only characterized by the possession of 7 antennal segments (one specimen has 6 segments), but by the mesosomal profile, with its short propodeum and a weak angulation between posterior and basal faces. The sides of the propodeum (basal face) are defined laterally. The medial clypeal hair is evident and clearly protrudes between the others, which are very short. A specimen (Fazenda Porto Alegre, Manaus, Brazil) has 6 segmented antennae, but in its general morphology corresponds to the concept of A. septemarticulatus.

The queen is very different from typical queens that belong to the genus in being smaller, yellow colored and having large black eyes.

Keys including this Species


Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb




The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • septemarticulatus. Allomerus septemarticulatus Mayr, 1878: 874 (w.) BRAZIL (Amazonas; “Nord-Brasilien in der Umgegend des Amazonenstromes”).
    • Forel, 1904e: 680 (q.).
    • Subspecies of octoarticulatus: Forel, 1904e: 680; Emery, 1922e: 189; Borgmeier, 1927c: 99.
    • Subspecies of decemarticulatus: Wheeler, W.M. 1942: 203; Kempf, 1972a: 19; Brandão, 1991: 324; Bolton, 1995b: 61.
    • Status as species: Dalla Torre, 1893: 78; Forel, 1895b: 125; Ettershank, 1966: 113; Fernández, 2007a: 171 (redescription).

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



Fernández 2007. Figure 5. Allomerus septemarticulatus. A, worker in lateral view; B, queen in lateral view, wings omitted.

Fernández (2007) - (n=4). HW 0.41-0.46 HL 0.46-0.48 SL 0.25-0.28 WL 0.49-0.53 GL 0.48-0.53 TL 1.83-1.93 CI 95-97 SI 57-59.

Anterior clypeal margin without distinct anteclypeus. Antennae 7 segmented (few workers with left antenna or both 6 segmented). Scapes fail to reach posterior lateral margin by about ¼ length, apical thickening less pronounced than in A. decemarticulatus. In side view, promesonotum convex. Metanotal suture reduced to single impressed line. Propodeal dorsal face very short, declivity and basal faces [same as dorsal face] with very feebly angulation. Propodeal spiracle small. Petiole with peduncle thickened posteriad, forming angle with node. Petiolar anteroventral spine small, well defined. Body smooth and shining, especially head. Sides of propodeum with short irregular carinulae. Long hairs (more or less 0.13 mm in length): two on the dorsum of head, near to posterior margin and down curved; two rows of several erect hairs on frons; about 8 on promesonotum, none on propodeum, several on petiole, postpetiole and gaster. Abundant short hairs (less than 0.07 mm), nearly appressed, on all body dorsum, few on propodeum. Row of very short anterior clypeal hairs, medial longest and conspicuous. All body light brown, hairs whitish.


Fernández (2007) - HW 0.88 HL 0.75 SL 0.50 WL 1.48 GL 1.45 TL 4.58 CI 117 SI 57.

In specimen observed, both antennae with 9 segments. Smaller and paler than typical Allomerus queens. Eyes very large, filling most of head in lateral view. Most of anterior part of head, especially between eyes and frontal carinae with fi ne longitudinal rugulae, as well as posterior part of mesoscutum and all of scutellum. Sides of propodeum, below propodeal spiracle, with longitudinal rugulae. Eyes and ocelli black, contrasting sharply with the yellowish, pale body. Hairs golden.