Pristomyrmex inermis

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

Pristomyrmex inermis casent0901727 p 1 high.jpg

Pristomyrmex inermis casent0901727 d 1 high.jpg

Specimen Labels

This species occurs in rainforest and has been collected in litter samples and on logs.

Identification

Wang (2003) – Worker. Propodeum lacking a pair of teeth or spines and this makes this species easily recognized. This is unique within Pristomyrmex. In addition, in the levigatus group, P. inermis has a characteristic shape of the petiole node in the workers and queens: wedge like in profile view with an apex. This character has originated independently at least twice in the genus because it is also seen in Pristomyrmex fossulatus and Pristomyrmex punctatus of the punctatus group.

A member of the Levigatus species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Indonesia, New Guinea.

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Pristomyrmex inermis 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.

  • inermis. Pristomyrmex inermis Wang, M. 2003: 496, figs. 209-212 (w.q.) NEW GUINEA.

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 2.86, HL 0.72, HW 0.70, CI 97, SL 0.64, SI 91, EL 0.14, PW 0.50, AL 0.72.

TL 2.65-3.36, HL 0.70-0.84, HW 0.69-0.84, CI 96-103, SL 0.62-0.76, SI 83-92, EL 0.12-0.16, PW 0.46-0.58, AL 0.63-0.80, PPW 0.23-0.27, PPL 0.17-0.21, PPI 128- 142 (n = 18).

Mandibles smooth and shining but sometimes with a few superficial small punctures. Masticatory margin of mandible with four teeth arranged as the strongest apical + the second strongest preapical + the smallest third + a basal tooth; a distinct diastema lacking. A broad-based triangular short tooth present about midway on the basal margin of mandible. Frontal area concave. Clypeus flat, smooth, and shining, its anterior margin with three denticles: a weak median tooth and one on each side, but sometimes the median tooth indistinct or lacking so that only two teeth are present there. Ventral surface of clypeus lacking any distinct rugae or teeth. Palp formula 1,3. Frontal carinae just extending to the level of the posterior margins of the eye s. Antennal scrobes absent. Frontal lobes very weak. Eyes moderately sized. Occipital margin feebly convex in full face view. Dorsum of alitrunk in profile arched. Pronotum unarmed. Propodeum lacking a pair of teeth or spines but usually with a pair of blunt small tubercles. Metapleural lobes small, usually bluntly rounded , but sometimes toothlike . Petiole node in profile wedge shaped, usually with a blunt triangular apex; sometimes the apex somewhat bluntly rounded. Subpetiole with a narrow rim. Postpetiole in profile slightly higher than the petiole node, with a convex dorsum. In dorsal view, petiole node and postpetiole broader than long. Cephalic dorsum between the frontal carinae highly polished but usually with a few foveolate punctures bordering frontal carinae. A few foveolate punctures present on the genae and many on the ventral surface of the head. Dorsum of alitrunk, petiole, and postpetiole smooth and shining. Gaster unsculptured. Dorsal surfaces of head, alitrunk, petiole, and postpetiole with sparse erect to suberect hairs. A few hairs present on the first gastral tergite. A few pairs of forward-projecting hairs present near the anterior clypeal margin. Scapes and tibiae with some suberect hairs. Color varying from light yellow-brown to blackish-brown, gaster usually darker than alitrunk; sometimes alitrunk lighter than head and gaster so that the specimens show a bicolored form.

Queen

TL 3.23-3.52, HL 0.80-0.81, HW 0.76-0.85, CI 95-106, SL 0.66-0.74, SI 87-92, EL 0.18-0.20, PW 0.64-0.72, AL 0.86-0.94, PPW 0.26-0.30, PPL 0.18-0.24, PPI 125-144 (n = 3).

General shape except for normal caste differences, other characters similar to worker.

Type Material

Holotype Worker. Los Angeles County Museum of Natural History. Indonesia: Irian Jaya, PT. Freeport Concession, Siewa Camp., 03.04°S 136.38°E, 200 ft, lowland secondary rainforest, #98-71 (stray foragers in leaf litter), 12.iv.1998 (R. R. Snelling). Paratypes. 17 workers and three queens (Australian National Insect Collection, LACM, Museum of Comparative Zoology, The Natural History Museum). Papua New Guinea, New Guinea.

References

  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 496, figs. 209-212 worker, queen described)