Pristomyrmex Mayr

Bolton, B., 1981, A revision of six minor genera of Myrmicinae (Hymenoptera: Formicidae) in the Ethiopian zoogeographical region., Bulletin of the British Museum (Natural History) Entomology 43, pp. 245-307 : 282-283

PRISTOMYRMEX Mayr (Figs 33 - 37)

Pristomyrmex Mayr , 1866: 903. Type-species: Pristomyrmex pungens Mayr , op. cit.: 904; by monotypy.

Odontomyrmex Andre , 1905: 207. Type-species: Odontomyrmex quadridentatus Andre , op. cit.: 208; by monotypy. [Synonymy by Mann, 1919: 341.]

Hylidris Weber , 1941: 190. Type-species: Hylidris myersi Weber , loc. cit. (= Pristomyrmex africanus Karavaiev ); by original designation. [Synonymy by Brown, 1953: 9.]

Dodous Donisthorpe , 1946: 145. Type-species: Dodous trispinosus Donisthorpe , loc. cit.; by original designation. [Synonymy by Brown, 1971: 3.]

Diagnosis of worker. Distal portion of each mandible in anterior view suddenly broadened, much broader than proximal portion. Apical (masticatory) margin usually with 4 teeth arranged as apical + preapical- + short diastema 4 - 2 basais, of which the first basal is usually the smallest tooth. An offset basal denticle may also be present as may a tooth about midway on the basal margin. In some species there is a tendency for the two basal teeth to fuse, resulting in a broad basal tooth with two points. With wear these appear as a single broad blunt tooth. Less commonly the mandible with 3 teeth only (apical 4 - preapical + long diastema + single basal), or with 5 teeth. Palp formula usually 1, 3 or 2, 3 (1, 3 in africanus and orbiceps ; 2, 3 in trogor ; 5 extralimital species also dissected) but higher in pungens-group with 4, 3 in cribrarius and 5, 3 in pungens itself. Lateral portions of clypeus in front of antennal insertions reduced to a thin plate or ridge, often translucent and usually projecting. Median portion of clypeus shield-like, broad between the antennal insertions and frequently with a median carina, its anterior margin prominent and with a projecting apron which is usually equipped with teeth or denticles but sometimes is merely crenulate. Median portion of clypeus projecting over the mandibles when the latter are closed. Frontal lobes reduced or absent so that the articulations of the antennae are mostly or wholly exposed and the roughly circular depressed areas containing the antennal sockets are clearly visible. Frontal carinae variously developed, ranging from absent to conspicuous, sometimes bounded below by a genal carina running longitudinally outside the depressed area of the antennal insertions. Antennae with 11 segments, with a strong 3 - jointed apical club. Eyes present in all known species, situated approximately at the midlength of the sides of the head, very variable in size. Alitrunk fusiform, without sutures dorsally. Pronotum often armed with spines, teeth or tubercles of varying size but frequently only with minute prominences or unarmed. Propodeum with a pair of spines or teeth. Propodeal spiracle circular. Metapleural lobes present and usually conspicuous. Orifice of metapleural glands situated some distance up the pleuron, not in the posterior lower corner. Below the gland orifice is a smooth and usually concave area running down towards the coxa, the concave area is bounded by a ridge on each side and appears to be a specialized surface from which the products of the glands may evaporate easily. Petiole nodiform, with a long anterior peduncle. Gaster commonly without hairs or only very sparsely hairy. Sting long and very slender, the apical portion often very thin and hair-like.

Discounting synonyms and infraspecific forms the genus Pristomyrmex contains about 38 named species to date. Of these names five valid species belong to the Ethiopian region (see below), six to Australia (Taylor, 1965; 1968), and two to the Malagasy region (Brown, 1971). The remaining 26 names apply to the Oriental / Indo-Australian forms for which no synthesizing taxonomic study has ever been undertaken. Without doubt a proportion of these names represent synonyms and equally without doubt a fair number of new species from these regions await description, so 26 may in fact be a good indication of the actual number of species in the Oriental and Indo-Australian regions, with a preponderance of forms in the latter.

The genus most closely related to Pristomyrmex is the monotypic Perissomyrmex Smith (1947: 281), which differs mainly in having the antennae with only 9 segments, as opposed to 11 in Pristomyrmex . Perissomyrmex was based on a couple of specimens intercepted in quarantine in the U. S. A., ostensibly on a ship from Guatemala. But, although Kempf (1972: 182) includes Perissomyrmex in his Neotropic catalogue and that area has been tacitly accepted as the place of origin, there is no hard evidence that Guatemala is in fact the original home of the genus. It so resembles Pristomyrmex that an Old World origin must be suspected, and the recent discovery by Cesare Baroni Urbani of a second Perissomyrmex species in Bhutan (as yet undescribed) adds weight to the argument that South America is not the place of origin but that the specimens of the type-species were brought to the U. S. A., via Guatemala, from somewhere in the Oriental region, or possibly the Indo-Australian region, by human commerce.

Most Pristomyrmex species nest in rotten wood, either in fallen twigs in the litter layer or in larger pieces of timber. Some nest in rotten parts of standing trees but most appear to prefer the ground, foraging in the leaf litter and top soil. Of the five African species three, fossulatus , cribrarius and trogor , seem fairly limited in distribution, with the first known from South Africa, the second from South Africa and Mozambique, and the latter only from Zaire. P. orbiceps is widely distributed throughout the wet forest zones of west and central Africa whilst the last species, africanus , has an extremely wide range and seems able to inhabit woodlands and forests virtually throughout sub-Saharan Africa.