Pristomyrmex browni

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

Pristomyrmex browni casent0102287 profile 1.jpg

Pristomyrmex browni casent0102287 dorsal 1.jpg

Specimen labels

This species occurs in native forest.

Identification

Wang (2003) - Worker. Dorsal surfaces of head and alitrunk with dense regular striations; propodeal spines in dorsal view joined together at base and subparallel along their length; HW 0.82-0.90 and HL 0.88-1.01. Closely related to the Mauritian Pristomyrmex bispinosus and Pristomyrmex trispinosus. Characters separating P. browni from P. bispinosus and P. trispinosus are provided under P. bispinosus and P. trispinosus, respectively. The following additional characters should also be mentioned: In the workers of P. browni, the sculpture of the dorsal head consists mostly of longitudinal rugae, except for a few rugae around the antennal fossae; the two sides of the mesonotum each has a small tubercle. In P. trispinosus, many striations present on the dorsal head spread out from the center to the two sides; the mesonotum possesses a pair of strong digit-like prominences. In the type worker specimens of P. browni, the first gastral tergite possesses only recumbent hairs, and the occipital margin of the head in full-face view is deeply concave, which are different in P. bispinosus and P. trispinosus.

A member of the Trispinosus species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Malagasy Region: Mauritius (type locality), Réunion.

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.

  • browni. Pristomyrmex browni Wang, M. 2003: 485, figs. 197-198 (w.m.) MAURITIUS.

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 3.50, HL 0.92, HW 0.84, CI 91 , SL 0.88, SI l05, PW 0.46, AL 0.90. Paratypes, 11 workers and one male. TL 3.42-3.78, HL 0.92-1.00, HW 0.82-0.90, CI 87- 94, SL 0.86-0.97, SI 98- 111, EL 0.14-0.19, PW 0.44-0.50, AL 0.84-0.96, PPW 0.26-0.28, PPL 0.22-0.24, PPI 117- 127 (n = 11).

Mandibles smooth and shining. Masticatory margin of mandible with four teeth arranged as the strongest apical + the second strongest preapical + a relatively long (first) diastema + a small de nticle + a relatively short (second) diastema + a small basal denticle; sometimes the second diastema indistinct. Basal margin of mandible almost straight, lacking a toothlike prominence. Anterior margin of the median portion of clypeus with at least five toothlike prominence s, but sometimes two lateral denticles are fused into a broad lobe. Two ends of the anterior clypeal margin each with a strong subtriangular tooth. Ventral surface of clypeus lacking toothlike prominences. Clypeus usually with a few weak longitudinal rugae . Palp formula 1,2. Frontal carinae absent. Antennal scrobes absent. Frontal lobes nearly completely absent so that the antennal articulations are almost entirely exposed. Antennal scapes, when lying on the dorsal head, slightly surpassing the occipital margin by about one-eighth to one-seventh of their length. Eyes moderately sized. Occipital margin medially deeply emarginate. Alitrunk in profile with a convex promesonotum and a deeply concave propodeal dorsum. Pronotum with a pair of acute short spines. Mesonotum lacking spines or teeth but usually with three blunt small tubercles that are present on the posterior end and on the two sides, respectively. Propodeal spines in profile well developed, long, bent at about a right angle near the base. In dorsal view, propodeal spines somewhat laterally compressed; they are joined together at the base but subparallel along their length. Metapleural lobes small, triangular. Petiole node in profile nodiform with a long anterior peduncle; its anterodorsal angle is higher than the posterodorsal. Postpetiole in profile with a single curved anterior and dorsal surface, in dorsal view slightly broader than long and also broader than the petiole node. Dorsum of head entirely covered with regular coarse striations that consist of longitudinal rugae and a few rugae around the antennal fossae . Sides and dorsum of alitrunk sculptured with coarse circular striations evenly, but the center of mesonotum with a few coarse longitudinal rugae. Sides of petiole and postpetiole usually with a few superficial rugae. Gaster smooth and shining. Dorsal surfaces of head, alitrunk, petiole, and postpetiole with some erect or suberect hairs. First gastral tergite with numerous recumbent hairs. A row of forward-projecting hairs present near the anterior clypeal margin. Scapes and tibiae with numerous suberect short hairs. Color reddish-brown.

Male

TL 3.04, HL 0.58, HW 0.48, CI 83, SL 0.20, SI 42, HWE 0.76, EL 0.38, PW 0.73, AL 1.08, PPW 0.24, PPL 0.20, PPI 120 (n = 1).

Head, including the eyes, broader than long. Clypeus convex without a median longitudinal carina. Anterior clypeal margin transverse. Frontal carinae absent. Scapes only slightly longer than the first funicular segments but distinctly shorter than the rest of the funicular segments. On the mesoscutum, notauli distinct, showing a V shape; parapsidal furrows very superficial. Scutoscutellar sulcus with six narrow ridges. Propodeum weakly tuberculate, lacking teeth or spines. Metapleural lobes triangular. Middle and hind tibiae without any spurs. Petiole node in profile with a fairly long anterior peduncle; anterior face of the node, together with the dorsal surface of the peduncle, forming a declivity. Postpetiole in profile low and rounded dorsally and in dorsal view broader than long. Dorsum of head smooth and shining, but frontal area with a median longitudinal carina. Pronotum and mesoscutum rather smooth and shining, except for those marked sutures, but mesoscutellum with some longitudinal and reticulate rugae. Petiole smooth and shining but with a longitudinal carina present on each side of the dorsal surface. Postpetiole and gaster smooth and shining. All dorsal surfaces with abundant erect or suberect hairs. Scapes and tibiae with numerous erect or suberect short hairs. Color reddish-brown; wings slightly smoky.

Type Material

Holotype Worker. Museum of Comparative Zoology. Mauritius: Le Pouce Mt., 700 to 800 m, native forest, 1.iv.1969 (W. L. Brown). Worker Paratypes. (MCZC, Australian National Insect Collection, The Natural History Museum). Mauritius: Le Pouce Mt., 700 to 800 m, native forest, 4.iii.1977 (W. L. Brown). One paratype male, collected in Mauritius by W. L. Brown, was originally mounted together with a worker on the same pin.

References

  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 485, figs. 197-198)