Acanthostichus brevicornis

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Acanthostichus brevicornis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dorylinae
Genus: Acanthostichus
Species: A. brevicornis
Binomial name
Acanthostichus brevicornis
Emery, 1894

Acanthostichus brevicornis casent0173500 profile 1.jpg

Acanthostichus brevicornis casent0173500 dorsal 1.jpg

Specimen Label

Synonyms

This is the most commonly encountered species of Acanthostichus. It has been found under cow manure together with termites (Bruch, 1924) and is known to be a termite predator (Bruch, 1925). Mann (1916) found a small colony under a deeply imbedded stone.

Identification

A member of the brevicornis species complex. Mackay (1996) - The workers of this species can be distinguished from others in that the femur is very broad, the petiole is subquadrate, usually with a strongly concave anterior face. It can be differentiated from Acanthostichus femoralis and Acanthostichus sanchezorum in that the propodeal spiracle is positioned at the midline, not above midline as in the other two species. It is similar to Acanthostichus kirbyi (and other related species, see discussion of A. kirbyi), from which it can be distinguished as the dorsum of the petiole is often punctate, with elongate depressions, the anterior face is not strongly thickened, the lateral clypeal teeth are poorly developed and the femur is not incrassate in A. kirbyi. The male can usually be distinguished from other species as it has an elongate petiole, is small and is without bluish reflections (see key).

A Paraguay collection differs from the “typical” A. brevicornis in being strongly dimorphic, increasing the range of worker size. Additionally the anterior face of the petiole is nearly straight as seen from above.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina, Brazil, French Guiana (type locality), Guyana, Paraguay, Suriname.

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Biology

Mackay (2004) - A Paraguay collection was found nesting in the soil in grazed second growth vegetation. This species is not uncommon in that collection locality. Alex Wild (personal communication) saw it several times under logs and near the surface of the soil where he was digging. It was always found in disturbed habitats, e.g., grazed areas, lawns, nesting in red clay soil.

Castes

Worker

Nomenclature

Mackay 1996. Figures 11-33.
Mackay 1996. Figures 34-49.

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

  • brevicornis. Acanthostichus brevicornis Emery, 1894c: 142 (w.) FRENCH GUIANA. Mackay, 2004: 98 (q.). Senior synonym of ramosmexiae: Kusnezov, 1962a: 130; Mackay, 1996: 144.
  • ramosmexiae. Acanthostichus ramosmexiae Bruch, 1924b: 260, fig. (w.) ARGENTINA. Bruch, 1925a: 110 (m.l.). Junior synonym of brevicornis: Kusnezov, 1962a: 130; Mackay, 1996: 144.

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

Description

Worker

Mackay (1996) - HL 0.74-0.96, HW 0.66-0.76, SL 0.31-0.38, WL 1.19-1.24, PW 0.35-0.40, PL 0.36-0.43, SI 39-42, CI 79-90, PI 100-106.

Mandible with only apical tooth developed; anterior medial border of clypeus concave, lateral clypeal teeth poorly developed; frontal carinae poorly developed, closely placed; head elongate, occipital border concave; petiole quadrate, anterior border strongly concave (Fig. 19), subpetiolar process a broadly rounded lobe (Fig. 20); femur flattened and incrassate (Fig. 43). Surface of body smooth and glossy (including scapes, dorsum of meso soma and dorsum of petiole).

Mackay (2004) - Additional measurements (n = 3): HL 0.71-1.07, HW 0.56-0.82, SL 0.30-0.40, SW 0.11-0.18, EL 0.04-0.06, WL 0.92-1.46, PL 0.29-0.47, PW 0.29-0.46, SI 37-42, CI 76-90, PI 100-106, SL/SW 2.20-2.73.

Queen

Mackay (2004) - HL 1.02, HW 1.01, SL 0.43, SW 0.19, EL 0.18, WL 1.67, PL 0.62, PW 0.83, Sl 42, CI 99, PI 50, SL/SW 2.25.

Subdichthadiiform, mandible without teeth (Fig. 6); anterior border of clypeus concave (Fig. 5); frontal carinae closely spaced, posterior border of head concave, sides of head rounded; malar groove poorly developed, extending from base of mandible slightly more than 0.1 mm, remainder of groove marked by very slight indentation; scape thickened; eye large, but failing to reach side of head by about ½ minimum diameter; ocelli absent; mesosoma basically rectangular as seen from side (Fig. 9), and as seen from above; promesonotal suture poorly developed, metanotal suture marked on dorsum of mesosoma; propodeal spiracle placed above midline (Fig. 9), propodeum rounded between faces; subpetiolar process absent (Fig. 9), petiole wider than long as seen from above, slightly wider posteriorly (Fig. 8); posterior femur slightly widened (Fig. 7), much less so than that of worker; pygidium without spines.

Erect hairs sparse; few hairs along anterior border of clypeus, and on mandible, along frontal carina, dorsum of head, posterior margin of head, dorsum of mesosoma, and legs; hairs on posterior face of propodeum fine, brushlike, with similar hairs on side and posterior margin of petiole; ventral surface of petiole with thick, closely spaced hairs; gaster with similar hairs on dorsal and ventral surfaces.

All surfaces smooth and glossy.

Yellow, mandibles and clypeus slightly darker.

Type Material

Mackay (1996) - FRENCH GUIANA: Cayenne (Museo Civico di Storia Naturale, Genoa) [examined]. Calen [?] Jelski; Typus; Acanthostichus parallelus [? Word marked out] brevicornis Em; Typhlomyrmex serratula [label obviously incorrect]

References