Pristomyrmex thoracicus

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Pristomyrmex thoracicus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. thoracicus
Binomial name
Pristomyrmex thoracicus
Taylor, 1965

MCZ-ENT00031153 Pristomyrmex thoracicus hal.jpg

MCZ-ENT00031153 Pristomyrmex thoracicus had.jpg

Type Specimen Label

This species occurs in rainforest nesting in rotting logs and in soil under logs (Taylor, 1965, 1968).

Identification

Wang (2003) - Worker. Pronotum with a pair of triangular short spines (ca. 0.06-0.08); propodeal spines long (ca. 0.19-0.24); dorsum of head, except for the antennal scrobes, with foveolate-reticulate sculpture; postpetiole unsculptured; PPI 109-121; SL 0.86-0.98 and SI 97-103.

Pristomyrmex thoracicus is so far known only from North Queensland, Australia. It is a Sibling species of Pristomyrmex foveolatus, also from North Queensland. Their differences are given under P. foveolatus.

A member of the quadridens species group.

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

Males have yet to be collected.

Nomenclature

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

  • thoracicus. Pristomyrmex thoracicus Taylor, 1965b: 41, figs. 3-6 (w.q.) AUSTRALIA. See also: Wang, M. 2003: 473.

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 3.22-3.72, HL 0.86-0.96, HW 0.86-0.96, CI 97-101, SL 0.86-0.98, SI 97-103, EL 0.10-0.13, PW 0.54-0.60, AL 0.84-0.96, PPW 0.23-0.26, PPL 0.20-0.22, PPI 109-121 (n = 24).

Mandibles with a few longitudinal rugae. Masticatory margin of mandible with three teeth arranged as an apical + a preapical + a long diastema + a truncated basal tooth. Basal margin of mandible lacking a distinct curved lobe or tooth. Clypeus with a strong median longitudinal carina. Anterior clypeal margin with a median denticle and usually two others on each side, but sometimes two lateral denticles are fused into a larger tooth. Ventral center of clypeus with a low, broad, toothlike prominence. Palp formula 2,3. Frontal carinae well developed, beyond the level of the posterior margins of the eyes. Scrobal areas shallow, present lateral to the frontal carinae in full-face view. Frontal lobes almost completely absent so that the antennal articulations are entirely exposed. Antennal scapes usually slightly surpassing the occipital margin of head when lying in the antennal scrobes. Eyes with five to six ommatidia in the longest row. Pronotum with a pair of triangular short spines, ca. 0.06 to 0.08. Propodeal spines long, ca. 0.19 to 0.24, usually slightly upcurved at their apices. Metapleural lobe small-triangular with a rather acute apex. Petiole node in profile higher than long, with a long anterior peduncle, its anterodorsal angle forming an apex and its dorsum sloping downward posteriorly. In dorsal view, crest of petiole node strongly convex. Postpetiole in profile rounded dorsally, in dorsal view broader than long and broadening from front to back. Dorsum of head between the frontal carinae, as well as the two sides of the dorsal head, with foveolate-reticulate sculpture. Antennal scrobes rather smooth, with only a few weak rugae. Dorsum of antennal scape with a longitudinal carina. Dorsum of alitrunk with a rugoreticulum. Petiole and postpetiole smooth and shining. Gaster unsculptured. Dorsal surfaces of head and alitrunk with numerous erect or suberect hairs. Dorsal surfaces of petiole node and postpetiole each with a pair of hairs. First gastral tergite lacking erect or suberect hairs. 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.

Queen

Wang (2003) - TL 3.84-4.10, HL 0.94-0.96, HW 0.94-0.96, CI 100-100, SL 0.94-0.96, SI 9B-I00, EL 0.16-0.18, PW 0.70- 0.72, AL 1.06-1.14, PPW 0.25-0.27, PPL 0.22-0.22, PPI 114-123 (m = 5).

General shape with normal caste differences from the conspecific worker; pronotum unarmed; crest of petiole node in dorsal view feebly convex; other characters similar to worker.

References

  • Taylor, R. W. 1965b. The Australian ants of the genus Pristomyrmex, with a case of apparent character displacement. Psyche (Camb.) 72: 35-54 (page 41, figs. 3-6 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 473, figs. 177-180 worker, queen described)