Dinoponera australis

A soil nesting species with small colonies that average 14 workers.

Identification
Lenhart et al. (2013) - Dinoponera australis is the most aberrant of the Dinoponera species because of its relatively small size, sparse non-flagellate pubescence, as well as the male characters (see below) which distinguish this species.

Worker. This species is most easily recognized by the antero-inferior corner of pronotum having a distinct tooth-like process, the pilosity being short and relatively sparse and the integument being finely micro-sculptured and dull. In addition the scape length is shorter than the head width and the total body length is under 30 mm. Dinoponera lucida could be confused with D. australis in that it also has a tooth-like process on the pronotum and can have a TBL under 30 mm, but differs in having the smooth and shiny integument, long flagellate hairs on lobe and forward slanting dorsal edge of petiole.

Male. Dinoponera australis males are recognized by their rounded head, with compound eyes, reduced ocelli and the posterior margin around the ocelli not protruding as in other species. This species is also characterized by the short, broad pygidial spine, volsella with tear-drop shaped basal lobe covered in minute teeth and aedeagus with a latero-apical fold, notches and teeth along ventral edge as shown in Fig.

Keys

 * Key to Dinoponera workers / Clave para la identificación de las obreras de Dinoponera / Chave para identificação de operários de Dinoponera
 * Key to Dinoponera males / Clave para la identificación de los machos conocidos de Dinoponera / Chave para identificação de machos de Dinoponera

Distribution
Dinoponera australis has the widest known range of the Dinoponera. This species is found in the department of Santa Cruz in Bolivia, southern Brazil in the states of Mato Grosso, Goias, Minas Gerais, São Paulo, Mato Grosso do Sul, Paraná, Santa Catarina and Rio Grande do Sul, eastern Paraguay in the departments of Itapúa, Alto Paraná and Guairá, as well as the province of Misiones in Argentina (Lenhart, Dash & Mackay, 2013).

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Bolivia, Brazil, Paraguay, Uruguay.

Nomenclature

 *  australis. Dinoponera grandis subsp. australis Emery, 1901a: 48 (w.) PARAGUAY. Santschi, 1921g: 85 (m.). Raised to species: Borgmeier, 1937b: 227. Senior synonym of brevis: Kempf, 1971: 382. Current subspecies: nominal plus bucki, nigricolor.
 * brevis. Dinoponera australis var. brevis Borgmeier, 1937b: 227 (w.) PARAGUAY. [First available use of Dinoponera grandis subsp. australis var. brevis Santschi, 1929a: 416; unavailable name.] Junior synonym of australis: Kempf, 1971: 382.

Worker
Lenhart et al. (2013) - (mm) (n=21) TBL: 23.42–29.31 (26.21); MDL: 3.59 – 4.31 (3.88); HL: 4.51–5.64 (4.99); HW: 4.31–5.74 (4.89); SL: 4.31–5.02 (4.73); WL: 6.25–7.69 (7.12); PL: 1.79–2.26 (2.03); PH: 2.56–3.28 (2.90); PW: 1.59–1.95 (1.75); GL: 7.28–9.64 (8.20); HFL: 5.54–6.66 (6.16).

A description of the external morphology of the worker is given by Kempf (1971): “Antennal scape length equal to, or shorter than head width. Pubescence on front of head short and inconspicuous. Gular face of head subopaque, finely reticulate-punctate throughout; the fine, arcuate striae variably developed from completely covering the undersurface of head to only vestigially shown antero-laterally or nearly absent. Sides of head reticulate-punctate, subopaque. Antero-inferior corner of pronotum dentate. Pronotal disc superficially reticulate and quite shining; paired swellings either feeble or distinct. Length of hind tibia equal to or less than head length. Petiole, in dorsal view, subquadrate, width over length proportion always more than 0.80, notably shorter and broader than in the other species; its shape…resembling that of mutica, with the upper anterior and posterior corners equally rounded; finely reticulate, somewhat shining; vertical sulcus on posterior surface either absent of more rarely vestigial to feebly developed. Terga I and II of gaster either reticulate-punctate or more superficially reticulate (in the southern range of the territory) and accordingly either subopaque or somewhat shining: fine appressed pubescence lacking completely on disc of the terga, present on the sides. Stridulatory file on acrotergite of tergum II of gaster well developed, broad and triangular, extending back to the acrotergite for about one half to two thirds of its length.”

Male
Lenhart et al. (2013) - A description of the external morphology of the male is given in Kempf (1971): “Head…with smaller eyes, the maximum interocular width being greater than their diameter; with smaller ocelli not protruding above the posterior border of head when seen in full-face view; antennal scape very short, less than twice as long as broad; funiculi without standing hairs; petiole distinctly shorter although variable in outline…; pygidium with a very short spine, not projecting beyond the long cerci; hypopygidium apically broadly truncate, the truncation either straight, or convex, or concave.”

Genitalia. Basal ring with thick dorso-anterior loop structures, reduced; parameres short, broad, rounded, small lobe on dorsal edge, emarginated ventro-basal edge; cuspis volsellaris with few bumps or teeth, digitus volsellaris with numerous small circular bumps at distal lateral face, tuft of setae on ventro-distal side of broad cusp, large tear-shaped lobe on basal ventral corner, covered in minute teeth; penis valve of aedeagus with lateral arm of apodeme at anterior border, no ventral concavity under ridge at base of apodeme, dorsal edge rounded, sloping posteriorly, ventro-anterior triangular projection followed by circular notch, ventral projecting tooth, smaller hemispherical notch with sclerotized border, thin, finely serrated distal edge, noticeable lateral apical fold with slight serration ending ventrally in serrated ridge, rounded un-serrated lobe at distal apex of valve.

Type Material
Lenhart et al. (2013) -Worker. BRAZIL: S. Paulo: Avanhandava [5 syntypes workers examined, ]; additional syntypes from PARAGUAY: Rio Apa, (leg.) Balzan, (leg.); ARGENTINA: Missiones, 1881, Berg (leg.), Giabibiri, Misiones, marzo 1884 G. Bove (leg.)