Pristomyrmex erythropygus

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Pristomyrmex erythropygus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. erythropygus
Binomial name
Pristomyrmex erythropygus
Taylor, 1968

This species occurs in rainforest and has been collected in rotten logs and in litter berlesates.

Identification

A member of the quadridens species group.

Wang (2003) - Worker. Masticatory margin of mandible with three teeth; anterior clypeal margin with three strong teeth; propodeal armaments, ca. 0.13 to 0.20, usually slightly longer than pronotal spines; dorsum of head smooth, but dorsal alitrunk with several longitudinal rugae present at the juncture between the pronotum and the mesonotum; first gastral tergite usually with erect or suberect hairs.

Pristomyrmex erythropygus is a sibling species of Pristomyrmex wheeleri and also related to Pristomyrmex quadridentatus. The three species are all from Australia. Pristomyrmex erythropygus differs from P. wheeleri and P. quadridentatus because the former possesses numerous erect or suberect hairs on the first gastral tergite and several short longitudinal rugae at the juncture between the pronotum and the mesonotum in the workers that are absent in the latter two species. In addition, the propodeal spines are usually slightly longer than the pronotal ones in the workers of P. erythropygus but much shorter than the pronotal spines in P. quadridentatus.

Keys including this Species

Distribution

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

The biology of most Pristomyrmex species is poorly known. From Wang (2003): Most species of Pristomyrmex dwell in the rainforest, foraging as predators or scavengers. An Asian species, Pristomyrmex punctatus, however, occurs in open and disturbed habitats (e.g., bare hills, agricultural areas, and beaches). These ants prefer to nest in soil, litter, or rotten wood; in rotten parts of living trees; in dead standing trees; or around plant roots.

Pristomyrmex is of great interest because it exhibits several unusual biological and evolutionary phenomena. The absence of morphologically normal queens and reproduction primarily by unmated workers in P. punctatus {=P. pungens) is a highly unusual life history in the Formicidae. Ergatoid queens, a special wingless female caste morphologically intermediate between the queen and the worker, are present in at least four species: Pristomyrmex punctatus, Pristomyrmex africanus, Pristomyrmex wheeleri, and Pristomyrmex mandibularis; two of them (P. africanus and P. wheeleri) possess both queen and ergatoid queen castes.

Simulating death, slowness of movement, and nocturnal foraging has been recorded in Pristomyrmex (Donisthorpe, 1946; Taylor, 1965; Weber, 1941). Colony size varies greatly among species, ranging from about a dozen to several thousand workers (Donisthorpe, 1946; Itow et al, 1984; Mann, 1919; Taylor, 1965, 1968).

Castes

Nomenclature

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

  • erythropygus. Pristomyrmex erythropygus Taylor, 1968c: 65 (w.q.) AUSTRALIA. [Misspelled as erythropus in Bolton, 1995b: 365.] See also: Wang, M. 2003: 441.

Type Material

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

Description

Worker

Wang (2003) - TL 3.48-3.90, HL 0.90-1.08, HW 0.94-1.18, CI 104-110, SL 0.92-1.00, SI 88-97, EL 0.16-0.20, PW 0.56-0.66, AL 0.84-0.98, PPW 0.24-0.30, PPL 0.19-0.23, PPI 114-130 (n = 8).

Mandibles generally smooth and shining but sometimes with a few basal longitudinal rugae. Dentition of the masticatory margin of mandible: an apical tooth + a preapical + a long diastema + a somewhat truncated basal tooth. Basal margin of mandible lacking a distinctly curved lobe or tooth. Clypeus with a median longitudinal carina. Anterior clypeal margin with three teeth: a median denticle and one on each side. Ventral surface of clypeus with a short transverse carina or with a low, broad prominence. Palp formula 2,2. Frontal carinae short, not extending to the level of the posterior margins of eyes. Antennal scrobes absent. Frontal lobes absent; thus, the antennal articulations are entirely exposed. Antennal scapes, laid on the dorsal head, slightly surpassing the occipital margin of head. Eyes containing eight to nine ommatidia in the longest row. Pronotum armed with a pair of moderately long spines, varying in length from 0.08 to 0.13. Propodeal spines usually slightly longer than pronotal ones, valying in length from 0.13 to 0.20. Metapleural lobes triangular and much shorter than propodeal spines. Petiole node in profile with the anterodorsal angle higher than the posterodorsal. Anterior and dorsal faces of the postpetiole in profile forming a single curved surface; in dorsal view, postpetiole distinctly broader than long. Dorsum of head smooth and shining, except for a few short rugae present below the frontal carinae around the antennal fossae and on the genae. Dorsum of alitrunk possessing (1) several short rugae present approximately at the juncture between the pronotum and the mesonotum (but weak in a smaller specimen), (2) a few transverse rugae present near the anterior pronotal margin, and (3) a transverse ridge present at the approximate position of metanotal groove. Petiole, postpetiole, and gaster smooth and shining. Dorsal surfaces of head and alitrunk with numerous erect or suberect hairs. Dorsal surfaces of petiole node and postpetiole, respectively, with a pair of bilaterally distributed long hairs; sometimes the crests of petiole node and postpetiole with additional one to two pairs of short hairs. First gastral tergite with numerous, evenly distributed, erect or suberect hairs. (Note: In three specimens placed under P. erythropygus, several longitudinal rugae are present at the juncture between the pronotum and the mesonotum, but erect or suberect hairs are absent from the first gastral tergite. Are these hairs artificially erased? Further collecting is needed to clarify this question.) A few pairs of forward-projecting hairs present near the anterior clypeal margin. Scapes and tibiae with some erect to suberect short hairs. Color reddish-brown to blackish-brown.

Queen

Wang (2003) - TL 4.40, HL 1.14, HW 1.27, CI 111, SL 1.02, SI 80, EL 0.22, PW 0.86, AL 1.20, PPW 0.34, PPL 0.24, PPI 142 (n = 1).

General shape with normal caste differences from the conspecific worker; pronotum unarmed; pro-mesonotum lacking longitudinal rugae; propodeal spines distinctly shorter than those in con specific worker; other characters similar to those in the conspecific worker.

References

  • Bolton, B. 1995b. A new general catalogue of the ants of the world. Cambridge, Mass.: Harvard University Press, 504 pp. (page 365, [Misspelled as erythropus in Bolton, 1995: 365.])
  • Taylor, R. W. 1968d. A supplement to the revision of Australian Pristomyrmex species (Hymenoptera: Formicidae). J. Aust. Entomol. Soc. 7: 63-66 (page 65, worker, queen described)
  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 441, see also)