Pristomyrmex largus

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

Pristomyrmex largus casent0178409 p 1 high.jpg

Pristomyrmex largus casent0178409 d 1 high.jpg

Specimen Labels

All paratypes of this species have been collected in high elevation rainforest, under the rain-soaked leaf litter, and inside a rotten ivory nut on the forest floor (R. Clouse).

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; HW and HL ≥ 0.90; petiole node in profile with the anterodorsal angle higher than the posterodorsal.

Pristomyrmex largus is the second largest species in the levigatus group after Pristomyrmex lucidus. Pristomyrmex largus must have evolved from the ancestor of Pristomyrmex levigatus. Pristomyrmex largus can be separated from P. levigatus by the following characters in the workers: P. largus - Larger species with HW 2 ≥ 0.90, and HL 2 ≥ 0.90. Propodeal spine s relatively long, longer than the distance between their bases. Ventral surface of head smooth, with only a few small hair pits. P. levigatus - Smaller species with HW < 0.80, and HL < 0.80. Propodeal armaments relatively short, shorter than or about as long as the distance between their bases. Ventral surface of head with numerous foveolate punctures.

A member of the Levigatus species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Micronesia (Federated States of) (type locality).

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.

  • largus. Pristomyrmex largus Wang, M. 2003: 497, figs. 213-214 (w.q.) MICRONESIA (Ponape I.).

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 3.38, HL 0.90, HW 0.96, Cl 107, SL 0.78, SI 81, EL 0.14, PW 0.61, AL 0.92, PPW 0.24, PPL 0.20, PPI 120.

TL 3.40, HL 0.90, HW 0.90, CI 100, SL 0.81, SI 90, EL 0.14, PW 0.60, AL 0.90, PPW 0.25, PPL 0.20, PPI 125 (n = 1).

Mandibles smooth and shining. A broad-based triangular short tooth present about midway on the basal margin of the mandible. Clypeus flat, unsculptured, smooth, and shining; its anterior margin with three denticles: a weak median tooth and one prominent lateral tooth on each side, sometimes the median tooth indistinct. Ventral surface of clypeus unsculptured and smooth. Palp formula 1,3. Frontal carinae just extending to the level of the posterior margins of eyes. Antennal scrobes absent. Frontal lobes weakly expanded. Eyes moderately sized. Occipital margin straight or feebly concave in full-face view. Pronotum unarmed. Propodeum with a pair of long spines that are about 1.5 times the distance between their bases. Metapleural lobes subtriangular. Dorsum of alitrunk in dorsal view rather flat. Petiole node in profile high, with the anterodorsal angle higher than the posterodorsal, its anterior face sometimes subparallel to the posterior one; anterior peduncle of the node about as long as the node, and subpetiole with a narrow semitranslucent rim. In dorsal view, petiole node trans-oval. Postpetiole in profile higher than long, rounded dorsally, in dorsal view broader than long and somewhat trans-rectangular. Both dorsal and ventral surfaces of head smooth and shining but with few small, shallow punctures present on the genae. Dorsum of alitrunk smooth and shining. Petiole and postpetiole smooth and shining, except for a lateral longitudinal carina on each side that separates the tergite from the sternite. Gaster unsculptured. Dorsal surfaces of head and alitrunk with some erect to suberect short hairs. Petiole node and postpetiole each with two pairs of hairs. A few hairs present near the base of the first gastral tergite. A few pairs of forward-projecting hairs present near the anterior clypeal margin. Scapes and tibiae with abundant erect to suberect short hairs. Color yellow-brown to reddish-brown.

Queen

TL 3.94, HL 0.94, HW 0.95, CI 101, SL 0.80, SI 84, EL 0.22, PW 0.74, AL 1.01, PPW 0.30, PPL 0.2.3, PPI 130 (n = 1).

Generally similar to worker, except for normal caste differences; in addition, propodeum with a pair of short spines, shorter than those in the conspecific worker, first gaster tergite with numerous hairs.

Type Material

Holotype Worker. Australian National Insect Collection. Ponape I., Mt. Tolenkiup; vi-ix.50 (P. A. Adams). Paratypes. 34 workers and one queen (Museum of Comparative Zoology, R. Clouse's personal collection). One worker, Micronesia: Pohnpei I., Hilltop campsite near Mt. Nanalaud, 400 m, on an old ivory nut, 3.v.1995 (Ron Clouse); 33 workers and one queen, Pohnpei I., Nahnalaud cave, around camp (#155-158, under dead leaves, on ground; #161, under rotting leaves; #167, under dead leaves; #178-180, leaves, under rotten), 24.iii.2000 (Ron Clouse).

References

  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 497, figs. 213-214 worker, queen described)