Pristomyrmex quadridens

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Pristomyrmex quadridens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. quadridens
Binomial name
Pristomyrmex quadridens
Emery, 1897

Pristomyrmex quadridens casent0178444 profile 1.jpg

Pristomyrmex quadridens casent0178444 dorsal 1.jpg

Specimen labels

Synonyms

This species occurs in rainforest and has been collected in litter, in rotten branch, and under the bark of a log.

Identification

Wang (2003) - Worker. Pronotum and propodeum each with a pair of short spines; dorsal surfaces of alitrunk and head between the frontal carinae with scattered foveolate punctures; petiole node and postpetiole each with at least a pair of hairs; HW 0.82-1.02, HL 0.82-1.02.

This species occurs in New Guinea, some islands near New Guinea, and Pohnpei Island. One of its closely related species, P. brevispinosus, is distributed in Indonesia, Malaysia, Thailand, the Philippines, Taiwan, and Japan; in other words, Pristomyrmex brevispinosus occurs to the northwest of P. quadridens. The differences between the workers of the two species are as follows: The dorsal surfaces of the head and the alitrunk possess scattered foveolate punctures in P. quadridens but foveolate-reticulate sculpture or rugoreticulum in P. brevispinosus.

Characters separating P. quadridens from Pristomyrmex nitidissimus of New Guinea are presented under P. nitidissimus. The three Australian species, Pristomyrmex wheeleri, Pristomyrmex erythropygus, and Pristomyrmex quadridentatus, differ from P. quadridens in the workers in having three strong teeth on the anterior clypeal margin, three teeth on the masticatory margin of the mandible, longer pronotal armaments, palp formula of 2,2, and lacking foveolate punctures on the dorsal surfaces of the head and the alitrunk.

A member of the Quadridens species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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

Distribution based on specimens

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

Worker

Nomenclature

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

  • quadridens. Pristomyrmex quadridens Emery, 1897c: 584, pl. 15, fig. 25 (w.q.) NEW GUINEA. Wang, M. 2003: 461 (m.). Senior synonym of aruensis, orbiculatus: Wang, M. 2003: 459.
  • aruensis. Pristomyrmex quadridens var. aruensis Karavaiev, 1933c: 270 (w.) INDONESIA (Aru I.). See also: Karavaiev, 1935a: 99. Junior synonym of quadridens: Wang, M. 2003: 459.
  • orbiculatus. Pristomyrmex orbiculatus Donisthorpe, 1948b: 306 (w.q.m.) NEW GUINEA. Junior synonym of quadridens: Wang, M. 2003: 459.

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 3.34-4.10, HL 0.82-1.02, HW 0.82-1.02, C1 96-102, SL 0.86-1.00, SI 96-105, EL 0.14-0.20, PW 0.54-0.70, AL 0.82-1.04, PPW 0.24-0.28, PPL 0.26-0.30, PPI 86-100 (n = 30).

Mandibles usually smooth and shining but sometimes with a few fine longitudinal rugae. Dentition of the masticatory margin of mandible: the strongest apical tooth + the second strongest preapical + a long diastema + two small teeth that are roughly the same size; sometimes two small basal teeth are fused, forming a broad tooth with two points. Basal margin of mandible lacking a distinct toothlike prominence. Clypeus depressed and smooth, with a median longitudinal carina, but sometimes this median carina weak or absent. Anterior clypeal margin usually with a median denticle and two to three others on each side. Ventral surface of clypeus with a toothlike prominence at the center. Palp formula 1,3. Frontal carinae distinct, extending to the level of the posterior margins of eyes. Antennal scrobes shallow and short. Frontal lobes weak; thus, the antennal articulations are almost entirely exposed. Antennal scapes, when lying on the dorsal head, slightly surpassing the occipital margin of head. Eyes usually containing seven to eight ommatidia in the longest row. Occipital margin feebly concave. Pronotum armed with a pair of acute short spines. Propodeum with a pair of triangular teeth or short spines that are about equal in length to the pronotal armaments. Metapleural lobes rounded or with a subtriangular apex. Petiole node in profile nodiform; its anterodorsal angle high, and the dorsum sloping downward posteriorly. Postpetiole in profile rounded dorsally, in dorsal view broadening from front to back and usually longer than broad but sometimes about as long as broad. Dorsum of head between the frontal carinae with scattered foveolate punctures; intensity and number of punctures very variable: The punctures are sometimes dense and large but sometimes few, small, and shallow. Dorsum of alitrunk with scattered foveolate punctures, varying from a few to many. Petiole, postpetiole, and gaster unsculptured, smooth, and shining. Dorsal surfaces of head and alitrunk with numerous erect or suberect hairs. Two pairs of hairs usually present on the dorsum of petiole node and a pair usually on the dorsum of postpetiole. First gastral tergite without erect or suberect hairs. A few pairs of forward-projecting hairs present near the anterior clypeal margin. Scapes and tibiae with abundant erect to suberect short hairs. Color varying from light yellow-brown to dark-brown; in some specimens, a darker circular patch present on the dorsum of head just above the frontal area; sometimes gaster darker than head and alitrunk.

Queen

Wang (2003) - TL 3.82-4.72, HL 0.90-1.10, HW 0.94-1.11, CI 98-10,5, SL 0.88-1.02, SI 90-99, EL 0.23-0.28, PW 0.74-0.88, AL 1.06-1.26, PPW 0.26-0.32, PPL 0.29-0.34, PPI 88-97 (n = 7).

General shape with normal caste differences from the conspecific worker; pronotum unarmed. Other characters similar to worker.

Male

Wang (2003) - Two male specimens, together with 12 workers and two queens, constitute a series collected in Indonesia (Seram, above Haruru, near Masohi, 50-150 m) by W L. Brown; each of the two males was originally mounted with a worker on the same pin: TL 3.30, 3.52; HL 0.60, 0.62; HW 0.60, 0.62; CI 100, 100; SL 0.23, 0.24; SI 38, 39; HWE 0.80, 0.82; EL 0.32, 0.33; PW 0.79, 0.82; AL 1.20, 1.20; PPW 0.22, 0.22; PPL 0.25, 0.27; PPI 81, 88 (n = 2).

Head, including the eyes, distinctly broader than long. Clypeus somewhat transverse, convex, and unsculptured. Palp formula 1,3. Frontal carinae absent. Maximum diameter of the median ocellus 0.11 to 0.12. On the mesoscutum, notauli pronounced, forming a Y shape; parapsidal furrows very weak. Scuto-scutellar sulcus with 10 narrow longitudinal ridges. Propodeum tuberculate, lacking teeth or spines. Metapleural lobes somewhat rounded. Petiole node in profile low and rounded dorsally, with a fairly long anterior peduncle. Postpetiole low, in dorsal view distinctly longer than broad. Dorsum of head smooth and shining. Alitrunk smooth and shining, except for those marked sutures. Petiole, postpetiole, and gaster smooth and shining. All dorsal surfaces with abundant long hairs. Scapes and tibiae with numerous erect or suberect short hairs. Color blackish-brown; hairs reddish-brown; wings somewhat infuscated.

Wang (2003):

Lectotype worker, New Guinea: Friedrich-Wilhelmshafen et Berlinhafen (L. Biro) (Museo Civico di Storia Naturale, Genoa), here designated, [examined].

Pristomyrmex quadridens aruensis. Holotype worker, Indonesia: Aru Is ., Wammar (W. Karawajew) (UENC) [examined].

Pristomyrmex orbiculatus. Syntype workers, queens and males, New Guinea: Maffin Bay, 20.vi.1944 (E. S. Ross) [syntype workers (The Natural History Museum, Los Angeles County Museum of Natural History, National Museum of Natural History) examined].

References

  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 459, Senior synonym of quadridens var. aruensis and orbiculatus)
  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 461, fig. 160-161, 274 queen, male described)