Pristomyrmex quadridentatus

This species occurs in rainforest. It forages nocturnally in the open on logs, tree trunks, and low foliage. Nests are located in rotting logs and under the bark sheaths of Bangalow palms (Taylor, 1965, 1968).

Identification
A member of the quadridens species group.

Wang (2003) - Worker. Pronotal spines ca. 0.15 to 0.24, much longer and more robust than propodeal armaments (ca. 0.06-0.09); dorsal surfaces of head and alitrunk smooth and shining, but a transverse ridge present at the approximate position of metanotal groove; petiole node and postpetiole each with at least one pair of erect or suberect hairs; ventral surface of dypeus usually with a long transverse ridge.

Pristomyrmex quadridentatus occurs in Australia. It is closely related to Pristomyrmex wheeleri, also from Australia. The workers of the two species share the following critical characters: (1) the masticatory margin of mandible with three teeth arranged as an apical + a preapical + a long diastema + a truncated basal tooth; (2) palp formula 2,2; (3) the anterior clypeal margin with three strong teeth; (4) the clypeus with a median longitudinal carina; (5) the pronotum with a pair of fairly long spines; (6) the dorsum of alitrunk smooth and shining but with a transverse carina present at the approximate position of metanotal groove; and (7) first gastral tergite lacking erect or suberect hairs. Pristomyrmex quadridentatus differs from P. wheeleri in the workers and queens, as follows: P. quadridentatus - Propodeum with a pair of teeth or short spines, ca. 0.06 to 0.09, much shorter than pronotal spines (worker). Propodeum tuberculate (queen). Ventral face of clypeus with a long transverse ridge or two toothlike prominences (worker and queen ). Head relatively narrow (worker: CI 93-101, HW 0.SO-1.0S; queen: CI 93-100, HW 0.90-1.12). Pronotum unarmed or with a pair of minute teeth (queen). P. wheeleri - Propodeum with a pair of fairly long spines, ca. 0.18 to 0.28, about equal in length to or longer than pronotal spines (worker); propodeum with a pair of spines (queen). Ventral center of clypeus usually with a short transverse carina; sometimes, this carina weak or indistinct (worker and queen). Head relatively broad (worker: CI 103-116, HW 0.97- 1.34; queen: CI 107-115, HW 1.18-1.42). Pronotum armed with a pair of acute short spines (queen).

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Biology
Wang (2003) - Taylor observes that there are two color forms of P. quadridentatus. One is a uniform reddish-brown and occupies the southern portion of its geographic range. The other is bicolored (head, gaster, and appendages reddish-brown but alitrunk, petiole, and postpetiole dark-brown) and occurs in more northern localities. Taylor found no evidence of sympatry of the two forms; thus, he postulated that the bicolored form might be result of character displacement where P. quadridentatus co-occurs with P. wheeleri (Taylor, 1965, 1968). However, six specimens, collected by P. Ward in 1976, have the same records of locality (New South Wales: Whian Whian, SF, 2S.39S/153.20E, rainforest, 200 m). The six specimens consists of two workers of each color form of P. quadridentatus and two workers of P. wheeleri. This collection implies that two forms of P. quadridentatus partly overlap in their distribution (in other words, character displacement is not the cause of the bicolored form in areas of sympatry with P. wheeleri). Of course, these data need to be further confirmed because they come from the labels on only a few specimens.

Taylor (1965) also proposed that the two color forms “might prove ultimately to be good biological species”, although there are no other detectable morphological differences between them. This question will be clarified by further collecting: If the two forms are never found to coexist in the same colony, they represent two good species; otherwise, they belong to the same species. (Note: To date, these two forms have not been collected in the same colony.

The larva of P. quadridentatus was described by Wheeler and Wheeler (1973).

Nomenclature

 *  quadridentatus. Odontomyrmex quadridentatus André, 1905: 208 (w.) AUSTRALIA. Taylor, 1965b: 47 (q.); Wheeler, G.C. & Wheeler, J. 1973a: 34 (l.); Wang, M. 2003: 465 (m.). Combination in Pristomyrmex: Forel, 1915b: 53. Senior synonym of queenslandensis: Taylor, 1965b: 43.
 * queenslandensis. Pristomyrmex (Odontomyrmex) quadridentatus var. queenslandensis Forel, 1915b: 53 (w.) AUSTRALIA. Junior synonym of quadridentatus: Taylor, 1965b: 43.

Worker
Wang (2003) - TL 3.34-4.42, HL 0.86-1.12, HW 0.80-1.08, CI 93-101, SL 0.86-1.16, SI 97-113, EL 0.16-0.20, PW 0.52-0.67, AL 0.83-1.10, PPW 0.22-0.26, PPL 0.22-0.28, PPI 93-109 (n = 52).

Mandibles usually smooth and shining but sometimes with a few longitudinal rugae, varying from superficial to distinct. Masticatory margin of mandible with three teeth arranged as the strongest apical + the second strongest pre apical + a long diastema + a truncated basal tooth. Basal margin of mandible almost straight, lacking a toothlike prominence. Clypeus with a strong median longitudinal carina. Anterior clypeal margin with three teeth: a median tooth and one on each side. Ventral surface of clypeus usually with a long transverse ridge but sometimes showing only two toothlike prominences. Palp formula 2,2. Frontal carinae usually extend but sometimes they are not so. Weak scrobal impressions present lateral to the frontal carinae. Frontal lobes weak; thus, the antennal articulations are almost entirely exposed. Antennal scapes, lying on the dorsal head, slightly surpassing the occipital margin of head. Between the second and seventh funicular segments of antennae, the second is longest. Eyes usually containing seven to eight ommatidia in the longest row. Occipital calina distinct. Pronotal spines, ca. 0.15 to 0.24, much longer and more robust than propodeal armaments, which are a pair of teeth or short spines (ca. 0.06-0.09). Metapleural lobes usually elongate-triangular, usually longer than propodeal armaments. Petiole node in profile, with the anterodorsal angle higher than the posterodorsal; in dorsal view, crest of the node convex. Anterior and dorsal faces of the postpetiole in profile forming a single curved surface. Postpetiole in dorsal view broadening from front to back. Dorsum of head smooth and shining, except for a short carina present below the antennal scrobe, subparallel to frontal carina. Dorsum of alitrunk smooth and shining, with a distinct transverse carina on the anterior margin of the pronotum and a transverse ridge present at the approximate position of metanotal groove. Petiole and postpetiole smooth and shining. Gaster unsculptured. Dorsal surfaces of head and alitrunk with numerous erect or suberect hairs. Petiole node and postpetiole each with bilaterally distributed hairs. First gastral tergite lacking erect or suberect hairs. A few pairs of forward-projecting hairs present near the anterior clypeal margin. Scapes and tibiae with some erect to suberect short hairs. Body self-colored (golden-brown) or bicolored (i.e., head, gaster, and appendages golden-brown to reddish-brown but alitrunk and pedicel segments blackish-brown).

Queen
Wang (2003) - TL 3.56-5.02, HL 0.93-l.16, HW 0.90-l.12, CI 93-100, SL 0.93-l.12, SI 96-103, PW 0.68-0.82, AL l.02-l.30, PPW 0.29-0.32, PPL 0.28-0.36, PPI 89-111 (n = 7).

General shape with normal caste differences from the conspecific worker; pronotum with a pair of tubercles or minute teeth or sometimes unarmed; propodeum with a pair of tubercles or minute teeth; other characters similar to worker.

Male
Wang (2003) - Four male specimens are examined; two of them, collected in New South Wales (New England N at. Park, Platypus Creek, STRF) by Nicholls, were originally mounted with two and three self-colored workers, respectively; one male, collected in SE Queensland (Rathdowney, Lever's Plateau, Philp's Farm) by J. B. Williams, and one in Queensland (National Pk.), by F. A. Perkins, were originally mounted with a bicolored worker, respectively.

TL 3.63-4.14, HL 0.60-0.68, HW 0.62-0.72, CI 103-106, SL 0.22-0.26, SI 34-37, HWE 0.84-0.93, EL 0.32-0.34, PW 0.82-0.86, AL 1.22-1.36, PPW 0.24-0.28, PPL 0.26-0.30, PPI 92-100 (n = 4).

Head, including the eyes, distinctly broader than long. Clypeus convex, lacking a median longitudinal carina, but with several short rugae present on the posterior clypeal margin. Anterior clypeal margin straight. Palp formula 2,2; the second segments of maxillary and labial palps rather long. Frontal carinae absent. Maximum diameter of the median ocellus 0.08 to 0.10. On the mesoscutum, notauli absent or weakly impressed or fairly distinct; parapsidal furrows absent or superficially impressed. Scuto-scutellar sulcus with 15 to 16 low, short ridges. Propodeum lacking armaments. Metapleural lobes subtriangular. Middle and hind tibiae without any spurs. Petiole node in profile low and rounded dorsally, with a long anterior peduncle. Postpetiole low, in dorsal view usually longer than rarely as long as broad. Posterior face of postpetiole almost entirely attached to the first gastral segment. Dorsum of head smooth and shining, but frontal area usually with a median longitudinal carina. Alitrunk smooth and shining, except for those marked sutures. Petiole, postpetiole, and gaster smooth and shining. All dorsal surfaces with abundant long hairs. Scapes and tibiae with numerous erect or suberect short hairs. Color reddish-brown to blackish-brown; wings infuscated.

References based on Global Ant Biodiversity Informatics

 * Taylor R. W. 1968. A supplement to the revision of Australian Pristomyrmex species (Hymenoptera: Formicidae). Journal of the Australian Entomological Society 7: 63-66.
 * Taylor R. W., and D. R. Brown. 1985. Formicoidea. Zoological Catalogue of Australia 2: 1-149.
 * Wang M. 2003. A Monographic Revision of the Ant Genus Pristomyrmex (Hymenoptera:Formicidae). Bull. Mus. Comp. Zool. 157(6): 383-542.
 * Wang M. 2003. A monographic revision of the ant genus Pristomyrmex (Hymenoptera:Formicidae). Bulletin of the Museum of Comparative Zoology 157(6):383-542