Acanthognathus rudis

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Acanthognathus rudis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Acanthognathus
Species: A. rudis
Binomial name
Acanthognathus rudis
Brown & Kempf, 1969

Acanthognathus rudis casent0280685 p 1 high.jpg

Acanthognathus rudis casent0280685 d 1 high.jpg

Specimen Labels

At a Glance • Ergatoid queen  



Keys including this Species


Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality), Paraguay.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


Nests in rotten wood.


Ergatoid queens occur as well as winged queens (Silva & Brandao 2014)


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

  • rudis. Acanthognathus rudis Brown & Kempf, 1969: 100, figs. 1, 2, 4-10 (w.q.m.) BRAZIL. Wheeler, G.C. & Wheeler, J. 1969: 110 (l.). See also: Dietz & Brandão, 1993: 683; Bolton, 2000: 17.



Holotype. TL 4.2, HL 0.93, H\V 0.65 (CI 70), ML 0.68 (MI 73), WL 0.86, petiole L in dorsal view 0.55, postpetiole L 0.20 (W 0.20), gaster L 0.97, greatest diameter of compound eye 0.3, scape L (chord to basal collar) 0.76 mm.

This species is so well known (under the name ocellatus) that Figs. 1, 2, and 4, and the measurements and indices, plus mention of a few outstanding features, should suffice to characterize it. Note the rather V-like outline of the posterior excision of the head. Head slightly more depressed, less convex above, than in A. ocellatus. The outstanding trait is the fine, nearly opaque, densely rugulose­ punctulate sculpture of head and truncus. Among the rugules are crowded numerous small piligerous fossae, especially on the dorsum of the head, but these are clearly visible only in certain lights. Sides of truncus finely punctulate-rugulose, except for the lowest part of the mesothorax, which is smooth and shining. The hairs are abun­dant, particularly on head and promesonotum, but also present on nodes, short and inclined, slender but blunt, often feebly flattened or clavate toward their apices, those on the head directed anteriad.

Pilosity otherwise as described for the genus.

Humeral angles obtuse, not strongly projecting. Propodeal teeth diverging, very feebly curved as seen from above.

The mandibles lack preapical armament, and there is not even a distinct welt at the site of the trigger hair, though a formation extending internally to the base of the hair can be seen within the transparent cuticle of the inner mandibula margin.

Petiole with a low, rounded node, the lower anterior slope with a low median carina; node about 0.22 mm long and 0.r 8 mm wide; postpetiole subglobular. Petiole and postpetiole densely and finely reticulo-punctulate and opaque, except for the almost completely smooth, shining nodal summits. Color light reddish ferruginous ; nodes and gaster yellowish fer­ruginous; but the gaster with the middle third shading into a broad brownish-red transverse band ; appendages yellow to straw.

Paratype variation is slight on the whole. Workers from Boraceia, S. Paulo State, have the upper as well as lower mesopleura largely smooth and shining. Color varies from light to medium ferruginous.


Measurements of a queen from the type locality are given in Table I. Her distinguishing specific characters correspond in the usual way to those of the worker. Mesonotum with crowded, slightly vermiculate longitudinal rugulae, interspersed with small fossae. Pronotum and propodeum transversely rugulose. Mesopleura with the upper half rugulose or smooth; lower half mostly smooth and shining.


from the type nest series: TL 2.8, HL 0.52, HW without eyes 0.45, with eyes 0.54, L antenna 2.0, ML 0.05, WL 0.90, L forewing 2.55 mm.

Smooth and shining, with small punctures abundant on head, a few rugae around the antennal insertions. Mesonotum finely and indistinctly longitudinally striolate-punctulate, sericeous-opaque. Color brown to piceous, head darkest (specimens may not be fully colored). Legs and mouthparts yellowish-tan.


  • Bolton, B. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). J. Nat. Hist. 3 33: 1639-1689 (page 1652, see also)
  • Bolton, B. 2000. The ant tribe Dacetini. Mem. Am. Entomol. Inst. 65: 1-1028 (page 17, see also)
  • Brandão, C. R. F. 1991. Adendos ao catálogo abreviado das formigas da região Neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412 (page 322, catalogue)
  • Brown, W. L., Jr. 1988h. Data on Malpighian tubule numbers in ants (Hymenoptera: Formicidae). Pp. 17-27 in: Trager, J. C. (ed.) Advances in myrmecology. Leiden: E. J. Brill, xxvii + 551 pp. (page 23, anatomy)
  • Brown, W. L., Jr.; Kempf, W. W. 1969. A revision of the neotropical dacetine ant genus Acanthognathus (Hymenoptera: Formicidae). Psyche (Camb.) 76: 87-109 PDF (page 100, figs. 1, 2, 4-10 worker, queen, male described)
  • Dietz, B. H.; Brandão, C. R. F. 1993. Comportamento de caça e dieta de Acanthognathus rudis Brown & Kempf, com comentários sobre a evolução da predação em Dacetini (Hymenoptera, Formicidae, Myrmicinae). Rev. Bras. Entomol. 37: 683-692 (page 683, behavior)
  • Fernández, F.; Palacio, E. E.; MacKay, W. P.; MacKay, E. S. 1996. Introducción al estudio de las hormigas (Hymenoptera: Formicidae) de Colombia. Pp. 349-412 in: Andrade, M. G., Amat García, G., Fernández, F. (eds.) Insectos de Colombia. Estudios escogido (page 381, anatomy, behavior)
  • Gronenberg, W.; Brandão, C. R. F.; Dietz, B. H.; Just, S. 1998. Trap-jaws revisited: the mandibular mechanism of the ant Acanthognathus. Physiol. Entomol. 23: 227-240 (page 227, anatomy, behavior)
  • Kempf, W. W. 1972b. Catálogo abreviado das formigas da regia~o Neotropical. Stud. Entomol. 15: 3-344 (page 9, catalogue)
  • Silva, T.S.R., Brandao, C.R.F. 2014. Further ergatoid gyne records in the ant tribe Dacetini (Formicidae: Myrmicinae). Neotropical Entomology 43, 161–171 (DOI 10.1007/s13744-013-0192-7).
  • Wheeler, G. C.; Wheeler, J. 1969. The larva of Acanthognathus (Hymenoptera: Formicidae). Psyche (Camb.) 76: 110-113 (page 110, larva described)