Pristomyrmex cribrarius

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Pristomyrmex cribrarius
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Pristomyrmex
Species: P. cribrarius
Binomial name
Pristomyrmex cribrarius
Arnold, 1926

MCZ-ENT00516173 Pristomyrmex cribrarius hal3-2.jpg

Pristomyrmex cribrarius had3-2.jpg

Specimen Label

Specimens have been collected by W. L. and D. E. Brown in South Africa on sand, in coast vine forest; by J. C. Faure, in South Africa (Zululand, St Lucia Lake), "by sifting the detritus and damp decaying leaves found under bushes (Arnold, 1948)"; and the holotype by G. Arnold on a tree trunk (Arnold, 1926).

Identification

Bolton (1981) - Easily separable from all the other African Pristomyrmex by its dense pilosity, coarse sculpture, high palp formula and oddly shaped postpetiole. Wang (2003) - Dorsal surfaces of head and alitrunk with foveolate-reticulate sculpture and postpetiole with a few coarse longitudinal rugae on each side.

The only member of the Cribrarius species group

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Kenya, Mozambique (type locality), South Africa, United Republic of Tanzania.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

This species was found in a leaf litter sample from very sandy soil.

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.

  • cribrarius. Pristomyrmex cribrarius Arnold, 1926: 281, fig. 81 (q.) MOZAMBIQUE. Arnold, 1948: 222 (w.). Combination in Hylidris: Weber, 1952: 17; in Pristomyrmex: Bolton, 1981b: 285. See also: Wang, M. 2003: 419.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Bolton (1981) - TL 3.2-3.4, HL 0.84-0.90, HW 0.86-0.92, CI 101-102, SL 0.66-0.72, SI 77-79, PW 0.56-0.60, AL 0.82-0.86 (3 measured).

Basal portions of mandibles rugulose but this fading out distally so that the area near the apical margin is mostly or entirely smooth. Apical (masticatory) margin of mandible with three teeth; apical and preapical tooth acute and roughly the same size, behind them is a long diastema followed by the broad and truncated basal tooth. The broad basal tooth may be the result of fusion of two denticles and specimens with a broad-based tooth but a bidenticulate crown must be expected. Clypeus with a strong sharp median longitudinal carina; anterior clypeal margin with a small truncated lobe medially where the carina meets the margin, this lobe flanked on each side by a few smaller denticles which are variable in number and shape. Palp formula 4, 3. Frontal carinae present and strongly divergent, reaching back to, or just beyond, the level of the posterior margins of the eyes. Below the frontal carinae to eye level is a short, weakly impressed scrobal area, bounded below by a weak genal carina which runs above the eye. Eyes large, maximum diameter 0'18-0'20, about 0•21-0•22 x HW and with 9-10 ommatidia in the longest row. With head in full-face view the occipital margin transverse to evenly very feebly concave, not indented medially. Pronotum armed with a pair of short but broad-based acute triangular teeth. Propodeum with a pair of long spines which are slightly sinuate along their length. Metapleural lobes small, bluntly triangular in shape. Dorsum of head between frontal carinae and back to occipital margin densely covered with broad, shallow foveolate punctures which are much broader than the distances separating them. In places the foveolae are roughly aligned so that the cuticle separating them appears as rugular sculpture. Similar sculpture is present below, behind and in front of the eyes, but the scrobal area lacks such sculpture and the clypeus is unsculptured except for the strong median carina. Entirety of dorsal alitrunk with strongly developed but blunt rugae which are predominantly longitudinal. Sides of alitrunk rugulose. Sides and dorsum of petiole node with a few coarse longitudinal rugae. Sides of postpetiole with a few strong rugae, the tergite in profile bounded by a raised ridge or rim. In dorsal view the rim appearing as in Fig. 35, the space between the converging lines being smooth and shiny. Gaster unsculptured. Dorsal surfaces of head, alitrunk, petiole and post petiole with abundant short erect to suberect hairs. Scapes and tibiae with similar freely projecting hairs and numerous hairs projecting from the sides of the head in full-face view. First gastral tergite without hairs. Colour brown, the gaster darker than the head and alitrunk but the appendages lighter.

Queen

Wang (2003) - TL 3.84, HL 0.98, HW 1.04, CI 106, SL 0.80, SI 77, EL 0.26, PW 0.82, AL 1.0.5, PPW 0.36, PPL 0.23, PPI 157 (n = 1).

Bolton (1981) - 3.8 mm. Head and petiole dark reddish brown, thorax dark yellowish brown, abdomen black, legs and antennae dark brownish ochreous. Shining, the abdomen very smooth and glabrous. A short, thin, sparse and yellowish pilosity on the head, thorax, petiole, antennae and legs, oblique on the legs, erect elsewhere. Pubescence wanting except on the flagellum. Cheeks, upper surface of the head, promesonotum and scutellum covered all over with wide, round and moderately deep pit-like punctures, which are much wider than the spaces between them. On the thorax some of the pits coalesce, forming longitudinal grooves. Both nodes of the petiole with wide and deep longitudinal sulci at the sides; the dorsum of the 1st node has 3 wide and longitudinal grooves, and the dorsum of the 2nd node has a wide shield-shaped and smooth area in the middle. Head, excluding the mandibles, a little wider than long, barely narrower behind than in front, the sides fairly convex, the posterior margin straight. The clypeus has a median carina somewhat widened and flattened in front, and the anterior margin bears on each side three small teeth. Mandibles smooth with 3 blunt teeth, the basal tooth largest, and separated by a wide space from the other two. Frontal carinae widely divergent, continued backwards as the upper margin of the scrobe. The latter ends at about the level of the posterior margin of the eye and is distinctly defined only in its upper half; its surface is fairly smooth except in front, where it is vertically striate. The scapes are a little longer than the scrobes; 2nd-6th joints of the flagellum wider than long, the 7th as long as wide. Eyes large and convex, placed at about the middle of the sides. Ocelli small and wide apart, smaller than most of the punctures on the head. Mesonotum nearly twice as wide as long, its anterior margin very convex; scutellum transversely oval, vertically truncate posteriorly. Epinotal spines horizontal, feebly divergent, acute and long, quite as long as the interval between them. First node of petiole about as long as wide above, vertically truncate, in front and at the sides, subquadrate or only a little narrower in front than behind. Second node one-third wider than the 1st, one-third wider than long, the shield-shaped area convex from front to back and merging gradually into the smooth anterior face. Abdomen globose, barely longer than wide. All the femora strongly swollen. Dealated. One specimen, on a tree trunk, Amatongas Forest, P.E.A..

Type Material

Bolton (1981) - Holotype female, Mozambique: Amatongas Forest (G. Arnold) (NM, Bulawayo) [examined]. (South African Museum)

References

  • Bolton, B. 1981b. A revision of six minor genera of Myrmicinae (Hymenoptera: Formicidae) in the Ethiopian zoogeographical region. Bull. Br. Mus. (Nat. Hist.) Entomol. 43: 245-307 (page 285, Combination in Pristomyrmex)