Pristomyrmex bicolor

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Pristomyrmex bicolor
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. bicolor
Binomial name
Pristomyrmex bicolor
Emery, 1900

Pristomyrmex bicolor casent0281796 p 1 high.jpg

Pristomyrmex bicolor casent0281796 d 1 high.jpg

Specimen Labels

Synonyms

This species occurs in rainforest and has been collected on fallen trees and rotten logs.

Identification

Wang (2003) - Worker. Masticatory margin of mandible with four teeth and a long diastema after the preapical tooth; pronotal spines exceptionally long (usually 0.40-0.66), much longer than propodeal armaments (teeth or short spines); dorsum of head sculptured with coarse rugoreticulum. P. bicolor is a highly variable species.

Only slight differences separate the workers of P. bicolor and of Pristomyrmex costatus, as follows: P. bicolor - Pronotal spines well developed and exceptionally long, usually 0.40 to 0.66 (rarely 0.37-0.39), and usually longer than the distance between their bases. Dorsal surfaces of petiole node and postpetiole usually with one to three pairs of hairs. Area between the bases of the pronotal spines smooth or sculptured; if sculptured, pronotal spine length is over 0.40. Larger species (HW usually 1.20-1.46, rarely 1.04-1.19; HL usually 1.20-1.42, rarely 1.08-1.19)

P. costatus - Pronotal spines moderately long, usually 0.18 to 0.27 (rarely 0.32), and shorter than the distance between their bases. Dorsal surfaces of petiole node and postpetiole with five or more pairs of hairs. Entire dorsum of alitrunk with developed rugoreticulum. Smaller species (HW 0.90- 1.16, HL 0.91-1.16)

Characters separating P. bicolor from Pristomyrmex curvulus are provided under P. curvulus. Pristomyrmex bicolor is also very similar in appearance to Pristomyrmex trachylissus. The two species are all from the Oriental region. The separation of the two species is summarized under P. trachylissus

A member of the Quadridens species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

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


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 not been collected.

Worker

Nomenclature

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

  • bicolor. Pristomyrmex trachylissa var. bicolor Emery, 1900d: 678 (w.) INDONESIA (Sumatra). Wang, M. 2003: 427 (q.). Raised to species and senior synonym of taurus: Wang, M. 2003: 425.
  • taurus. Pristomyrmex taurus Stitz, 1925: 120, fig. 5 (w.) PHILIPPINES. Junior synonym of bicolor: Wang, M. 2003: 425.

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 4.58-6.14, HL 1.04-1.42, HW 1.08-1.46, CI 98-109, SL 1.14-1.58, SI 106-120, EL 0.20-0.26, PW 0.65-0.96, AL 1.18-1.64, PPW 0.33-0.40, PPL 0.38-0.48, PPI 77-93 (n = 83).

Mandibles usually with several longitudinal rugae, varying from superficial to rather coarse. Masticatory margin of mandible with four teeth arranged as: two adjacent strong apical teeth + a long diastema + two small basal teeth that are roughly the same size. Basal margin of mandible lacking a distinctly curved lobe or tooth. Clypeus with a strong median longitudinal carina. Anterior clypeal margin sometimes with seven denticles: a median denticle and three others on each side, but sometimes one or a few are weak or indistinct, or two to three of the lateral denticles are fused into a larger one. Ventral center of clypeus usually with a transverse ruga of varying length, sometimes with a very weak prominence at middle and sometimes without either of these characters. Palp formula 1,3. Frontal carinae strong, extending to the level of the posterior margins of eyes. Slightly concave scrobal areas pre sent. Frontal lobes absent; thus, the antennal articulations are entirely exposed. Antennal scapes, when lying on the dorsal head, usually surpassing the occipital margin by one-third to one-fourth of their length. Eyes usually containing 10 to 12 ommatidia in the longest row.. Pronotal spines well developed and exceptionally long, varying in length, usually 0.40 to 0.66, but in a few specimens they are 0.37 to 0.39. Propodeum usually with a pair of acute short spines, which are 0.12 to 0.20, much more slender and much shorter than the pronotal ones. Propodeal armaments occasionally reduced to a pair of teeth. Both pronotal and propodeal spines upward pointed. Metapleural lobes subtriangular. In profile, petiole node high, with a long anterior peduncle; its anterodorsal angle elevated above the posterodorsal. In dorsal view, crest of petiole node rounded. Postpetiole in profile convex dorsally, in dorsal view longer than broad and broadening from front to back. Dorsum of head with well-developed coarse rugoreticulum. Dorsal surface of alitrunk variably sculpture d: At one extreme, in a series from North Borneo (SE, Forest Camp, 9.8 km SW of Tenom), the dorsum of alitrunk is entirely rugoreticulate. In a few other series, the rugoreticulum is absent between the bases of two pronotal spines, and some weak rugae or a smooth (broad or narrow) area are present there. At the other extreme, the sculpture is completely absent, and the area is smooth and shining on the anterior half of the dorsum, but the rest of the dorsal alitrunk is coarsely rugulose. Sides of pronotum with a rugoreticulum or many large coarse foveolate punctures. Sides of the rest of alitrunk irregularly coarsely rugulose . Dorsal surfaces of petiole node and postpetiole smooth and shining, but a longitudinal ruga present on each side of petiole. Gaster unsculptured, smooth, and shining. Dorsal surfaces of head and alitrunk with numerous erect or suberect hairs. Petiole node with a few (usually two to three) pairs of hairs dorsally. Dorsum of postpetiole with at least a pair of hairs. First gastral tergite lacking erect or suberect hairs. A row of forward projecting hairs present near the anterior clypeal margin. Scapes and tibiae with some erect or suberect hairs. Color usually reddish-brown but sometimes black-brown.

Queen

Wang (2003) - TL 6.54, 6.56; HL 1.34, 1.44; HW 1.38, 1.50; CI 103, 104; SL 1.48, 1.51; SI 99, 109; EL 0.32, 0.34; PW 1.20, 1.24; AL 1.72, 1.82; PPW 0.41, 0.43; PPL 0.48, 0.48; PPI 85, 90 (n = 2).

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

Type Material

Wang (2003):

Syntype workers, Sumatra: Si-Rambe, xii.l890-iii.1891 (E. Modigliani) (Museo Civico di Storia Naturale, Genoa, NHMV, National Museum of Natural History) [examined].

Pristomyrmex taurus Holotype worker, Philippines: N. Palawan, Binaluan, xi.xii.1913 (G. Boettcher) (Berlin Museum für Naturkunde der Humboldt-Universität) [examined].

References