Proceratium australe

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Proceratium australe
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. australe
Binomial name
Proceratium australe
De Andrade, 2003

Proceratium australe casent0172121 profile 1.jpg

Proceratium australe casent0172121 dorsal 1.jpg

Specimen labels

Nothing is known about the biology of Proceratium australe.

Identification

A Proceratium species belonging to the silaceum clade and resembling Proceratium siamense, but differing from it, in the worker, by the narrower petiole and by the hairs of type 2 shorter.

Keys including this Species

Distribution

Australia: Queensland, New South Wales.

Distribution based on Regional Taxon Lists

Australasian Region: Australia (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Very little is known about the biology of Proceratium ants. They nest in soil, rotten wood, under deep-set stones and, in a few cases, tree branches. For many species the nest consists of small rounded chambers hollowed out of soft rotten wood or in the soil. Toward the cooler limits of the range, particularly in North America, nests and foraging workers are found under deep set rocks instead of in rotten wood. The nest site is usually in forest shade, in old moist gardens, or similar habitats that are constantly moist. Some species of known to be egg predators of arthropods, especially of spiders.

Most Proceratium are relatively rare but this is not the full explanation for why they are not commonly collected. Colonies of most species are small. Based on anectdotal natural history information from a few species, it was once thought that most Proceratium would likely be found to have mature colonies that contain somewhere between 10 - 50 workers. Yet nests with more than 50, and in some cases up to 200, workers have been been reported. Besides small colonies, these ants also do not appear to forage in places where they are readily encountered.

Males and females are though to be produced in small numbers but we generally do not have enough data for colonies of any species to know what might be typical. Reproductive flights have been observered toward the end of the summer in some northern temperate areas. In these regions the nuptial flight occurs during the last half of August. Both sexes climb some distance from the nest entrance before taking flight. Workers too issue from the nest during the nuptial flight, as is often the case with otherwise cryptobiotic ants.

Castes

Queen

Nomenclature

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

  • australe. Proceratium australe De Andrade, in Baroni Urbani & De Andrade, 2003b: 345, fig. 137 (w.q.) AUSTRALIA.

Type Material

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

Baroni Urbani and de Andrade (2003) - Proceratium australe is a very variable species. The specimens from Lake Eacham are the most similar to the type series. What we regard as intraspecific variation affects sculptural and structural details listed in the following.

A worker from Tallebudgera Creek has poorly angulate propodeal sides and more superficial sculpture on the mesosoma. A worker from Mt. Kembla and the one from Bruxner Park have more marked postpetiolar sculpture, the erect hairs slightly longer and darker colour. In addition, a worker from Bruxner Park has narrower petiolar node.

A worker from Malanda (Ross & Cavagnaro leg.) has more superficial postpetiolar sculpture, subangulate propodeal sides and narrower petiolar node. A worker from Malanda collected by Brown also has more or less shining sculpture and propodeal sides with the most obtuse trace of angulation according to Brown (1958a).

Workers from Lamington and Roy National Parks are slightly larger (TL ≥ 3.26 mm instead of 2.57-3.09 mm).

Gynes from Barry and from Cooloola have small eyes (EL 0.14-0.15 mm instead of 0.19-0.21 mm). A gyne from Landsborough is larger than the other gynes examined (TL 3.75 mm instead of 3.14-3.61 mm). A gyne from Landsborough has higher CI (98.6 as opposed to 93.8-95.8). A gyne from Cooper Creek has very superficial postpetiolar sculpture.

Based on the material available for the present study we prefer to adopt the conservative position of considering all these specimens as belonging to a single, variable species.

Description

Worker

Head slightly longer than broad and with the sides gently diverging posteriorly. Vertex in full face view almost straight. Clypeus reduced and as long as the antennal sockets. Anterior border of the clypeus truncate. Frontal carinae not very far from each other, slightly covering the antennal insertions. Lateral expansions of the frontal carinae not very narrow, little raised, strongly diverging on the two anterior fourths, converging on the third fourth, subparallel and carinate only on the last fourth. Frontal area gently concave on the three anterior fourths and with a central longitudinal carina starting from the last fourth and prolonging posteriorly. Head anterolaterally with a thick, short, longitudinal carina. Genal carinae marked, each carina corresponding to the external border of a deep sulcus. Eyes visible as a dark dot below the integument, small and on the middle of the head sides. First funicular joint about as long as broad. Funicular joints 2-10 broader than long. Last funicular joint as long as the sum of joints 6-10. Scapes short of the vertexal margin and gently thickening apically. Masticatory margin of the mandibles with 7-8 denticles before the pointed apical tooth. Palp formula 2,2.

Mesosoma gently convex and about as long as the maximum head length (mandibles included) in profile. Pronotal and propodeal sutures absent. Basal face of the propodeum declivous posteriorly. Declivous face of the propodeum flat. Area between the basal and declivous faces of the propodeum weakly concave, dorsally carinate and laterally angulate. Sides of the declivous face of the propodeurn carinate. Propodeal spiracle round and above mid height in lateral view.

Petiole subrectangular and not very narrow; its anterior border straight and anterolaterally carinate. Ventral process of the petiole spine-like and directed backwards. Postpetiolar sternite anteromedially with a marked subtriangular projection, gently convex posteriorly in side view. Constriction between postpetiole and gaster impressed. Gastral tergite I about 1/3 longer than the postpetiole and convex on the curvature. Posterior border of the gastral tergite I thick and irregular. Remaining gastral tergites and sternites curved ventrally.

Legs not very short. All tibiae with a pectinate spur. Spurs of fore legs without basal spine. Fore basitarsi longer than the mid ones. Hind basitarsi about 1/4 shorter than hind tibiae. Second tarsoinere of hind legs about as long as the pretarsus. Pretarsal claws simple. Arolia absent.

Sculpture. Anterior half of the head and head sides with dense piligerous foveae mixed with irregular rugosities. Posterior half of the head dorsum, mesosoma, petiole and postpetiole densely punctate and with very sparse, short, irregular, rugosities, the punctures more superficial on the anterior half of the mesosoma. In addition the propodeal dorsum, petiole and postpetiole with sparse granulation. Caster smooth and with minutely piligerous punctures denser and larger on the sides. Legs punctate.

Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body, suberect and sparse on the funicular joints; (2) longer than type (1), erect on the whole body, slightly shorter on the scapes, absent on the funiculi (3) shorter than hair type (1), dense and decumbent on the funicular joints only. In addition the funicular joints bear whitish, thick, appressed, sparse hairs.

Colour. Light ferrugineous with lighter antennae and legs.

Measurements in mm and Indices: TL 2.56-3.44; HL 0.60-0.77; HW 0.54-0.73; EL 0.03-0.04; SL 0.39-0.51; WL 0.69-0.97; PeL 0.18-0.23; PeW 0.27-0.34; HFeL 0.41-0.58; HTiL 0.34-0.46; HBaL 0.26-0.36; LS4 0.28-0.36; LT4 0.55-0.72; CI 90.0-95.8; SI 63.9-68.7; IGR 0.48-0.52.

Queen

Differing from the worker in the following details: eyes large, slightly less than 1/3 of the head length, colnposed by many facets and with ocular pilosity. Ocelli well developed.

Mesosoma robust and convex in side view. Parapsidal furrows marked. Scutellum with the sides gently converging posteriorly and with the posterior border subtruncate. Dorsum of the scutellum with a thick longitudinal carina. Metanotum with a small tooth. Basal face of the propodeum medially concave. Area between the basal and declivous faces of the propodeum carinate and subangulate on each side.

Paratype Specimen Labels

Measurements in mm and Indices: TL 3.14-3.75; HL 0.65-0.74; HW 0.61-0.73; EL 0.14-0.21; SL 0.43-0.51; WL 0.94-1.10; PeL 0.22-0.23; PeW 0.33-0.37; HFeL 0.52-0.61; HTiL 0.42-0.49; HBaL 0.33-0.39; LS4 0.34-0.44; LT4 0.68-0.90; CI 93.8-98.6; SI 65.7-68.9; IGR 0.47-0.50.

Type Material

Holotype worker from Australia labeled: "Queensland, 17.10S, 145.39E, Boar Pocket, rainforest, 720m, R. W. Taylor, 9-12.X.1986, ANIC ANTS VIAL 44.122"; seven paratype workers and one paratype gyne, same data as the holotype; holotype worker, 5 paratype workers and 1 paratype gyne, in Australian National Insect Collection, 2 paratype workers in Museu de Zoologia da Universidade de Sao Paulo.

Etymology

"Australe" is a neologism indicating the provenance from Australia.

References

  • Baroni Urbani, C., de Andrade, M.L. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie, 36, 1–492. (page 345, fig. 137 worker, queen described)