Pristomyrmex minusculus

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Pristomyrmex minusculus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. minusculus
Binomial name
Pristomyrmex minusculus
Wang, M., 2003

Pristomyrmex minusculus casent0178458 profile 1.jpg

Pristomyrmex minusculus casent0178458 dorsal 1.jpg

Specimen labels

This species occurs in rainforest and has been collected in litter samples, and in a rotting tree.

Identification

Wang (2003) - Worker. Masticatory margin of mandible lacking a diastema and possessing four teeth, of which the third tooth, counting from the apex, smallest; pronotum with a pair of teeth.

This species has a wide distribution in the Oriental region. It is also dispersed to North Queensland, Australia. Pristomyrmex minusculus must be derived from a P. levigatus-like ancestor. It is indistinguishable, in the queen, from Pristomyrmex levigatus at present. The workers of P. minusculus have almost same appearance as those of P. levigatus, except for a derived character-the pronotum with a pair of small teeth. In the levigatus group, this critical character is possessed only by the workers of P. minusculus, thus making them easily recognizable.

A member of the levigatus species group.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Australasian Region: Australia.
Indo-Australian Region: Indonesia, Micronesia (Federated States of), New Guinea, Palau, Tonga (type locality).

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Pristomyrmex minusculus for further details

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.

  • minusculus. Pristomyrmex minusculus Wang, M. 2003: 507, figs. 229-232 (w.q.) PALAU IS (Peleliu I.).

Type Material

Holotype Worker. Museum of Comparative Zoology. Palau Is: Peleliu I., east coast, 26.i.1948 (H. S. Dybas). Paratypes, 16 workers and one queen (MCZC, Australian National Insect Collection, The Natural History Museum, NACA). Nine workers and one queen with same data as holotype; one worker, Wallis Is.: NukuTapu I., 28.iii.1965 to l.iv.1965 (G. Hunt). Two workers, Indonesia: Seram, above Haruru, near Masohi, 50 to 1.50 m, 18.iii.1981 (W. L. Brown); one worker, Indonesia: Irian Jaya, 12 km S of Sorong, forest fragment, l.v.1981 (W. L. Brown); two workers, Tonga Is.: Falehau, Niuatoputapu, moss + lichen, from coconut tree trunks, l.ix.1971 (W. and G. Rogers); two workers, YapGroup, vii-viii.50. (R. J. Goss).

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

Description

Worker

Holotype. TL 3.02, HL 0.76, HW 0.80, CI 105, SL 0.66, SI 83, EL 0.14, PW 0.52, AL 0.78. Workers. TL 2.52-3.02, HL 0.66-0.78, HW 0.66-0.80, CI 99-106, SL 0.54-0.66, SI 77-84, EL 0.10-0.14, PW 0.45-0.52, AL 0.59-0.74, PPW 0.20-0.24, PPL 0.14-0.19, PPI 126-143 (n = 16).

Mandibles usually smooth and shining but sometimes with a few small shallow punctures. A broad-based short tooth present about midway on the basal margin of the mandible. Clypeus unsculptured. Anterior clypeal margin with a median tooth and two lateral teeth, but the median tooth often smaller than the others, sometimes the median tooth indistinct. Ventral surface of clypeus with a weak transverse ruga. Palp formula 1,3. Frontal carinae extending to the level of the posterior margins of the eyes. Scrobal areas shallow, short, present lateral to the frontal carinae in full-face view. Frontal lobes weakly expanded. Eyes moderately sized. Occipital margin feebly concave. Alitrunk in dorsal view more or less flat. Pronotum with a pair of acute small teeth; in some small specimens, this pair of teeth are very weak but visible, and in dorsal view they become a pair of sharp points on the two sides of the pronotum. Propodeum armed with a pair of spines, varying in length and shape, straight to slightly upcurved along their length. Metapleural lobes subtriangular, but rarely with a rounded apex. Petiole node in profile high with the anterodorsal angle higher than the posterodorsal, its anterior surface usually subparallel to the posterior one, its anterior peduncle about as long as the node. Subpetiole with a narrow rim. Postpetiole in profile high, rounded dorsally. Petiole node and postpetiole in dorsal view broader than long. Dorsum of head between the frontal carinae smooth and shining but sometimes with a few foveolate punctures bordering the frontal carinae, present on the genae and around the eyes. Dorsum of alitrunk smooth and shining. Petiole and postpetiole each with a lateral longitudinal ruga on each side that separates the tergite from the sternite. Gaster unsculptured. Dorsal surfaces of head and alitrunk with sparse erect to suberect hairs. Dorsal surfaces of petiole node and postpetiole each usually with two pairs of hairs and first gastral tergite with a few 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 yellow-brown to reddish-brown; appendages lighter.

Queen

TL 3.08, HL 0.72, HW 0.74, CI 103, SL 0.60, SI 81, EL 0.17, PW 0.60, AL 0.82, PPW 0.24, PPL 0.18, PPI 133 (n = 1).

Generally similar to worker, except for normal caste differences. In addition, pronotal armaments absent; propodeum with a pair of teeth or short spines that are shorter than those in the con specific worker.

References

  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 507, figs. 229-232 worker, queen described)