Pristomyrmex flatus

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

Pristomyrmex flatus casent0901722 p 1 high.jpg

Pristomyrmex flatus casent0901722 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Pristomyrmex flatus.


Wang (2003) - Worker. Pronotum and propodeum each with a pair of short spines; dorsal surfaces of head and alitrunk smooth and unsculptured; petiole node with at least two pairs of hairs; anterior face of petiole node indistinguishable from the upper surface of its anterior peduncle; HW 0.98-l.04 and HL 0.94-l.02.

Like Pristomyrmex collinus, P. flatus is also known only from the Philippines. Pristomyrmex flatus is similar to P. collinus, Pristomyrmex quadridens, Pristomyrmex africanus, Pristomyrmex trogor, Pristomyrmex quadridentatus, Pristomyrmex wheeleri, and Pristomyrmex erythropygus. The workers of P. flatus can be immediately recognized; because in P. flatus, the anterior face of the petiole node is not distinct from the upper surface of its anterior peduncle, which is different in the previously mentioned species.

A more detailed discussion of the separation of P. flatus from P. collinus is provided under P. collinus. Pristomyrmex flatus and P. collinus differ from P. quadridens in the workers as follows: P. flatus and P. collinus - Dorsum of alitrunk unsculptured, smooth, and shining. Dorsum of head smooth and shining, except for a few punctures bordering the frontal carinae. P. quadridens - Dorsum of alitrunk with scattered foveolate punctures; sometimes some short rugae present. Dorsum of head with a few to many foveolate punctures, except for those bordering the frontal carinae.

Pristomyrmex flatus and P. collinus differ from two African species, P. africanus and P. trogor, in the workers as follows: P. flatus and P. collinus - Ventral center of clypeus with a short ruga or small toothlike prominence. At least one to two pairs of hairs present on the petiole node and postpetiole. Metapleurallobes triangular. P. africanus and P. trogor - Ventral surface of clypeus with two teeth. Petiole and postpe tiole lacking erect or suberect hairs. Metapleural lobes rounded. The other differences include that the anterior face of the petiole node is distinct from the upper surface of the peduncle in the workers of P. africanus and P. trogor but almost indistinct in P. flatus; the dorsum of the alitrunk in dorsal view is convex in the workers of P. collinus but distinctly shallowly concave in P. africanus and P. trogor; the dorsum of the head is sculptured with scattered foveolate punctures in the workers of P. africanus but is generally smooth and shining in P. flatus and P. collinus; the frontal carinae extend to the level of the posterior margins of eyes in the workers of P. flatus and P. collinus but not so in P. trogor.

A member of the Quadridens species group

Keys including this Species


Distribution based on Regional Taxon Lists

Indo-Australian Region: Philippines (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


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).


Queens have not been collected. The described males are only tentatively associated with this species.



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

  • flatus. Pristomyrmex flatus Wang, M. 2003: 443, figs. 138-139 (w.m.) PHILIPPINES.

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



Holotype TL 3.94, HL 1.02, HW l.04, CI 102, SL l.10, SI 106, EL 0.24, PW 0.66, AL l.03.

TL 3.79-4.14, HL 0.94-1.02, HWV 0.98-1.04, CI 102-106, SL 1.02-1.12, SI 104-108, EL 0.22-0.24, PW 0.64-0.67, AL l.02-1.08, PPW 0.28-0.30, PPL 0.28-0.30, PPI 93-100 (n = 4).

Mandibles generally smooth and shining, with a few basal short rugae. Dentition of the masticatory margin of mandible: the strongest apical tooth + the second strongest preapical + a long diastema + two small denticles that are about equal in size. Basal margin of mandible lacking a toothlike prominence. Clypeus d e pressed and smooth, but the frontal area with a median carina that extends a little to the clypeus. Anterior clypeal margin usually with a median denticle and three other small denticles on each side, but sometimes one of the lateral denticles very weak and indistinct. Ventral center of clypeus with a weak, toothlike prominence. Palp formula 1,3. Frontal carinae approximately reaching to the level of the posterior margins of eyes. Antennal scrobes absent. Frontal lobes very weak so that the antennal articulations are almost completely exposed. Antennal scapes rather long, when lying on the dorsal head, surpassing the occipital margin by one -fifth to one-fourth of their length. Eyes containing eight to nine ommatidia in the longest row. Propodeum with a pair of slender acute spines that are directed upward and slightly longer than the pronotal ones. Metapleural lobes subtriangular. Pronotum and mesonotum in dorsal view slightly concave between the pronotal spines and between the two lateral margins of mesonotum, respectively. Petiole node massive; its anterior face in profile indistinguishable from the upper surface of petiole peduncle. Dorsum of petiole node in dorsal view about rounded. Postpetiole in profile convex dorsally, in dorsal view slightly longer than broad or about as long as broad, broadening from front to back. Dorsum of head usually smooth and shining, but some small and shallow hair pits present. Dorsum of alitrunk unsculptured, smooth and shining. Sides and dorsum of petiole and postpetiole smooth and shining. Gaster unsculptured. Dorsal surfaces of head with numerous erect or suberect hairs. Dorsum of alitrunk with sparse erect to suberect hairs. Two pairs of hairs present on the dorsum of petiole node, and two to three pairs on the dorsum of postpetiole. First gastral tergite lacking erect or suberect hairs. A few pairs of forward-projecting hairs pre sent near the anterior clypeal margin. Scapes and tibiae with numerous erect to suberect short hairs. Color reddish-brown but sometimes yellow-brown.


The following five male specimens, with same data as holotype and paratypes, may represent the male of this species. I tentatively place these males under P. flatus, which needs further confirmation.

TL 3.62-3.94, HL 0.64-0.68, HW 0.56-0.59, CI 8.5-91, SL 0.22-0.25, SI 39-43, HWE 0.98-1.04, EL 0.48-0.51, PW 0.74-0.80, AL 1.16-1.24, PPW 0.24- 0.24, PPL 0.24-0.24, PPI 100-100 (n = 5).

Head, including the eyes, much broader than long; while excluding the eyes, distinctly longer than broad. Eyes very large and prominent; their length is about three-fourths of the head length. Clypeus convex, somewhat semicircular, its anterior margin straight and posterior one semicircular. Palp formula 1,3. Frontal carinae absent or short, slightly beyond the anterior margins of antennal insertions. Frontal area usually with a median longitudinal carina. Ocelli developed; maximum diameter of median ocellus 0.16 to 0.18. On the mesoscutum, notauli distinct, forming a Y shape, but usually without distinct ridges in them; parapsidal furrows absent. Scutoscutellar sulcus usually with 9 to 10 narrow ridges. Propodeum lacking armaments. Metapleural lobes subtriangular. Middle and hind tibiae without any spurs. Petiole node in profile low, with a subtriangular apex and a rather long anterior peduncle; anterior face of the node, together with the dorsal surface of its anterior peduncle, forming a long declivity, which reaches the top of the node. Postpetiole in profile low, rounded dorsally, in dorsal view about as broad as long. Dorsum of head smooth and shining, except for a few short rugae present on the posterior margin of clypeus. Alitrunk generally smooth and shining, except for those marked sutures. Petiole, postpetiole, and gaster unsculptured, smooth, and shining. All dorsal surfaces with abundant long hairs. Scapes and tibiae with numerous erect or suberect short hairs. Color reddish-brown; hairs reddish-brown; antennae sometimes yellow-brown; wings somewhat infuscated.

Type Material

Holotype Worker. Museum of Comparative Zoology. Philippines: Luzon I., Bauqui; xi.1923. (R.C.Mcq.). Paratypes. MCZC, The Natural History Museum.Three workers with same data as holotype.


  • Wang, M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542 (page 443, figs. 138-139 worker, male described)