Pristomyrmex trachylissus

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Pristomyrmex trachylissus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. trachylissus
Binomial name
Pristomyrmex trachylissus
(Smith, F., 1858)

Pristomyrmex trachylissus casent0901717 p 1 high.jpg

Pristomyrmex trachylissus casent0901717 d 1 high.jpg

Specimen Labels

This species occurs in rainforest and has been collected on a rotten log.

Identification

Wang (2003) - Worker. Large size (HL > 1.36, HW > 1.45); masticatory margin of mandible with five teeth; pronotum with a pair of exceptionally long spines that are about as long as the distance between their bases.

Pristomyrmex trachylissus must have evolved from the ancestor of Pristomyrmex bicolor: It is extremely similar in appearance of the workers and queens to P. bicolor: The two species may occur sympatrically in Sarawak and in Sabah. Their workers and queens can be separated by the following characters: P. trachylissus - Masticatory margin of mandible with five teeth; diastema indistinct or very short. Basal margin of mandible with a central, broadly curved lobe. Anterior clypeal margin with a median tooth and a broad, short prominence on each side SI < 100 (only in worker). P. bicolor - Masticatory margin of mandible with four teeth; a long diastema present between the preapical and the third tooth. Basal margin of mandible lacking a distinctly curved lobe Antelior clypeal margin usually with seven denticles, but in some specimens, two or three lateral denticles fused into a broadly convex lobe. SI > 105 (only in worker).

A member of the Quadridens species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo (type locality), Indonesia, Malaysia.
Oriental Region: Thailand.

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.

  • trachylissus. Myrmica trachylissa Smith, F. 1858b: 126 (q.) BORNEO. Mayr, 1886c: 359 (w.). Combination in Pristomyrmex: Mayr, 1886c: 359. Wang, M. 2003: 474 (w.). See also: Emery, 1887b: 450.

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 5.58-6.48, HL l.36-l.46, HW 1.45-l.62, C1 107-114, SL l.40-l.50, S1 90-98, EL 0.22-0.24, PW 0.92-l.02, AL l.50-l.64, PPW 0.35-0.39, PPL 0.44-0.48, PP1 76-83 (n = 6).

Mandibles generally smooth and shining, except for a few superficial rugae. Masticatory margin of mandible with five teeth arranged as the strongest apical + the second strongest preapical + a small third tooth + a short diastema (or this diastema indistinct) + two small basal teeth. Basal margin of mandible with a central, broadly curved lobe. Clypeus with a strong median longitudinal carina. Anterior clypeal margin with a median denticle and a broad prominence on each side. Ventral surface of clypeus generally smooth and shining but sometimes with a weak, short, transverse ruga at the center. Frontal carinae strong, extending to the level of the posterior margins of the eyes. Antennal scrobes shallow, present lateral to the frontal carinae. Frontal lobes weak; thus, the antennal articulations are almost entirely exposed. Antennal scapes, laid on the dorsal head, slightly surpassing the occipital margin of head. Eyes with 10 to 11 ommatidia in the longest row. Pronotum armed with a pair of robust, exceptionally long spines, ca. 0.40 to 0.50, about as long as the distance between their bases. Propodeum with a pair of short spines, ca. 0.12 to 0.18, shorter than or at most about as long as the distance between the bases of two propodeal spines. Metapleural lobes each with a somewhat blunt-rounded apex. Petiole node in profile high, with a long anterior peduncle; its anterodorsal angle is on a higher level than the posterodorsal. Postpetiole in profile rounded dorsally, in dorsal view longer than broad and broadening from front to back. Dorsum of head entirely sculptured with well-developed coarse rugoreticulum. Similar sculpture present on the dorsum of alitrunk and on the two sides of pronotum, except for the space between the bases of two pronotal spines, which is rather smooth. Petiole smooth and shining but with a lateral longitudinal carina on each side. Postpetiole and gaster unsculptured, smooth, and shining. Dorsal surfaces of head and alitrunk with numerous erect or suberect hairs. A few pairs of hairs pre sent on the dorsum of petiole node and at least a pair on the postpetiole. First gastral tergite lackng erect or suberect hairs. A few pairs of forward-projecting hairs present near the anterior clypeal margin. Scapes and tibiae with some erect or suberect hairs. Color reddish-brown, but the masticatory margins and the basal margins of mandibles and the funiculi of antennae black-brown.

Queen

Wang (2003) - TL 7.55, HL l.84, HW 2.14, CI 116, SL- (antennal scapes missing), SI-, PW 1.52, AL 2.10 (n = 1).

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

Type Material

Wang (2003) - Holotype queen, Borneo (A. H. Wallace) (The Natural History Museum) [examined].

References

  • Emery, C. 1887g. Catalogo delle formiche esistenti nelle collezioni del Museo Civico di Genova. Parte terza. Formiche della regione Indo-Malese e dell'Australia (continuazione e fine). [part]. Ann. Mus. Civ. Stor. Nat. 25[=(2)(5): 449-464 (page 450, see also)
  • Mayr, G. 1886c. Notizen über die Formiciden-Sammlung des British Museum in London. Verh. K-K. Zool.-Bot. Ges. Wien 36: 353-368 (page 359, Combination in Pristomyrmex)
  • Smith, F. 1858a. Catalogue of hymenopterous insects in the collection of the British Museum. Part VI. Formicidae. London: British Museum, 216 pp. (page 126, queen described)
  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 474, figs. 181-184 worker, queen described)