Acanthognathus brevicornis

Very little is known about the biology of these ants. Col­lections have shown, however, that the colonies are small and that they are found in the soil or in rotting wood. No infor­mation is available on feeding habits, but the species of Acan­thognathus are probably predaceous like some of their close relatives.

Identification
The length and shape of the antennal scape, and the nature of the sculpturing of the head and thorax readily distinguish the worker of brevicornis from those of the other species.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Colombia, Ecuador, Guyana, Panama, Peru.

Biology
The ants (type material) were collected sometime during the period from June to October 1943, and bear the label, Zetek No. 5105, Nothing is known concerning their biology.

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

Nomenclature

 * . Acanthognathus brevicornis Smith, M.R. 1944c: 151 (w.q.) PANAMA (Barro Colorado I.).
 * Type-material: holotype worker, 3 paratype queens.
 * Type-locality: holotype Panama: Canal Zone, Barro Colorado I., vi-x.1943, Zetek No. 5105, USNM 56862 (J. Zetek); paratypes with same data.
 * Type-depositories: USNM (holotype); MCZC, USNM (paratypes).
 * Silva, T.S.R. & Brandão, 2014: 163 (ergatoid q.).
 * Status as species: Kempf, 1964e: 67; Brown & Kempf, 1969: 94 (redescription); Kempf, 1972a: 9; Bolton, 1995b: 53; Bolton, 1999: 1652; Bolton, 2000: 16; Sosa-Calvo, et al. 2006: 820; Galvis & Fernández, 2009: 246; Sosa-Calvo, et al. 2010: 39 (in key); Silva, T.S.R. & Brandão, 2014: 163; Bezděčková, et al. 2015: 114; Fernández & Serna, 2019: 831.
 * Distribution: Brazil, Colombia, Guyana, Panama, Peru.

Type Material
Described from a holotype worker and an allotype female. Two paratype females do not differ appreciably from the allotype. All of these are deposited in the United States National Museum under U.S.N.M. No. 56862.

Worker
Length (including mandibles)   3  mm.

Head subcordate, the posterior border strongly and angularly emarginate. Antenna 11-segmented;  scape  short   (approximately  three-fourths   the   length of the head measured from the anterior border of the clypeus to the posterior corner), not attaining the posterior border at any point, slender, curved and enlarged toward the apex but narrowing again before its junction with the funiculus; first, ninth,  and  tenth  funicular  segments  long,  the  second  through the eighth short and somewhat, indistinct. Eye placed approximately  at  the middle of the side of the head, oval, well developed, with about 7 to 8 facets in its greatest diameter. Clypeus longer than broad, subtruncate anteriorly, with the posterior border extending between the frontal carinae to the  approximate limits of the latter. Frontal carinae short, each forming  a  prominent  lobe which conceals the insertion of the antenna. Mandibles 0.86 mm. long (slightly shorter than the head), elongate, slender, subparallel, porrect, each with 3 curved, hook-like apical teeth, the median of which is the longest. Inner border of mandible with a slight enlargement near the middle, and a number  of  very minute denticulae between the  enlargement and the apex. Ventral surface of each mandible near the base with a slender, curved spine which is apically bidentate and is  directed  somewhat  mesoposteriorly. Humerus of  prothorax with a prominent, tubercle-like spine. Promesonotal suture more or less indistinct. Mesoepinotal impression pronounced. Epinotum higher than long and bearing a pair of well-developed,  acutely  tipped spines. Petiole strongly pedunculate. Petiole and postpetiole rather nodiform, and without spongiform processes  such as occur in  Strumigenys.

Head with a shining appearance due to the nature of the sculpturing which consists of rather sparse, subcircular depressions, each bearing a central elevation from which arises a short, curved, bluntly tipped or claviform hair. In the posterior part of the head the punctures are either absent or else separated by a space more than their greatest diameter. All the interspaces are smooth and shining. Thorax so weakly sculptured that it is also shining. Body dark reddish brown with slightly lighter appendages.

Queen
Dealated. Length (including mandibles)  3.85  mm.

Besides the usual caste differences the female differs from the worker in its larger size, more convex and larger eyes (with 12-13 facets in their greatest di­ameter) and coarser sculpturing on the head. The punctures on the head are not dense enough to give the head a subopaque appearance.

References based on Global Ant Biodiversity Informatics

 * Amat-G G., M. G. Andrade-C. and F. Fernández. (eds.) 1999. Insectos de Colombia. Volumen II. Bogotá: Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 433 pp. 131975
 * Baroni Urbani C., and M. L. De Andrade. 1994. First description of fossil Dacetini ants with a critical analysis of the current classification of the tribe (Amber Collection Stuttgart: Hymenoptera, Formicidae. VI: Dacetini). Stuttgarter Beiträge zur Naturkunde. Serie B (Geologie und Paläontologie) 198: 1-65.
 * Bezdeckova K., P. Bedecka, and I. Machar. 2015. A checklist of the ants (Hymenoptera: Formicidae) of Peru. Zootaxa 4020 (1): 101–133.
 * Brown W. L., and W. W. Kempf. 1969. A revision of the Neotropical dacetine ant genus Acanthognathus (Hymenoptera: Formicidae). Psyche 76: 87-109.
 * Donoso David. Personal communication. Ants of Barro Colorado Island.
 * Feitosa R. dos S. M. and A. S. Ribeiro. 2005. Mirmecofauna (Hymenoptera, Formicidae) de serapilheira de uma área de Floresta Atlântica no Parque Estadual daCantareira  São Paulo, Brasil. Biotemas 18: 51-71.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
 * Groc S., J. H. C. Delabie, F. Fernandez, M. Leponce, J. Orivel, R. Silvestre, Heraldo L. Vasconcelos, and A. Dejean. 2013. Leaf-litter ant communities (Hymenoptera: Formicidae) in a pristine Guianese rainforest: stable functional structure versus high species turnover. Myrmecological News 19: 43-51.
 * Instituto Nacional de Pesquisas de Amazonia (GBIF)
 * Lapolla, J.S., T. Suman, J. Soso-Calvo and T.R. Schultz. 2006. Leaf litter ant diversity in Guyana. Biodiversity and Conservation 16:491510
 * Museo de Entomología de la Universidad del Valle (GBIF)
 * Silva R. R., R. S. Machado Feitosa, and F. Eberhardt. 2007. Reduced ant diversity along a habitat regeneration gradient in the southern Brazilian Atlantic Forest. Forest Ecology and Management 240: 61-69.
 * Silva R.R., and C. R. F. Brandao. 2014. Ecosystem-Wide Morphological Structure of Leaf-Litter Ant Communities along a Tropical Latitudinal Gradient. PLoSONE 9(3): e93049. doi:10.1371/journal.pone.0093049
 * Silva T. S. R., and C. R. F. Brandao. 2014. Further Ergatoid Gyne Records in the Ant Tribe Dacetini (Formicidae: Myrmicinae). Neotrop. Entomol DOI 10.1007/s13744-013-0192-7
 * Sosa-Calvo J., T. R. Schultz, and J. S. LaPolla. 2010. A review of the dacetine ants of Guyana (Formicidae: Myrmicinae). Journal of Hymenoptera Research 19: 12-43.