Pristomyrmex brevispinosus

Colony size is small in Pristomyrmex brevispinosus, with less than 20 workers per nest. Ergatoid females are present (Onoyama, 1976; Terayama, 1999). The nests are found in rotting wood or under stones in forested habitats. A closely related species occurs in Taiwan and southern China, but it has normal alate queens and no ergatoids. Within Japan this species is known only from Iriomote Island in the Nansei Islands.

Identification
Wang (2003) - Masticatory margin of mandible with at most four teeth; pronotal armaments toothlike, about long as propodeal armaments that are a pair of tri-angular teeth or short spines; dorsum of head, at least behind the level of eyes, with foveolate-reticulate sculpture or rugoreticulum. It is obvious that P. brevispinosus has evolved from a Pristomyrmex quadridens-like ancestor. Pristomyrmex brevispinosus possesses densely assembled foveolate punctures (i.e., foveolate-reticulate sculpture) or rugoreticulum on the cephalic dorsum in the workers and queens, on the dorsal alitrunk in the workers, and on the sides of the pronotum in the workers and queens. But P. quadridens has only scattered foveolate punctures in these areas.

Some intermediate forms are present between P. brevispinosus and P. quadridens, but they may be easily assigned to either of the two species as follows: Those populations possessing a few coarse longitudinal carinae or some coarse rugae on the dorsum of the alitrunk or possessing foveolate-reticulate sculpture only behind the eyes should be assigned to P. brevispinosus, but those possessing only foveolate punctures and lacking coarse longitudinal carinae or rugae on the dorsal alitrunk should be assigned to P. quadridens.

The male of P. brevispinosus is indistinguishable at present from that of Pristomyrmex quadridens; this strengthens the conclusion that these two species are closely related. Another close relative of P. brevispinosus is Pristomyrmex sulcatus; their differentiation is discussed under P. sulcatus. Characters separating P. brevispinosus from the two Australian species, Pristomyrmex foveolatus and Pristomyrmex thoracicus, are provided under P. foveolatus.

A member of the Quadridens species group

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Krakatau Islands, Malaysia, New Guinea, Philippines, Singapore. Oriental Region: India, Taiwan, Thailand. Palaearctic Region: China, Japan.

Nomenclature

 *  brevispinosus. Pristomyrmex brevispinosus Emery, 1887b: 451 (w.m.) INDONESIA (Sumatra). Senior synonym of formosae, yaeyamensis: Wang, M. 2003: 428. See also: Lin & Wu, 1998: 95.
 * formosae. Pristomyrmex formosae Lin & Wu, 1998: 95, figs. 33-36 (w.) TAIWAN. Senior synonym of yaeyamensis (because Yamane & Terayama, 1999: 20 state that yaeyamensis was based on "formosae Forel, an invalid name", as also was formosae Lin & Wu. Hence formosae Lin & Wu is automatically synonymous with yaeyamensis and both are junior synonyms of brevispinosus: Wang, M. 2003: 428.) See also: Xu & Zhang, 2002: 69.
 * yaeyamensis. Pristomyrmex yaeyamensis Yamane & Terayama, 1999: 18, figs. 1-3 (w.q.) JAPAN. Junior synonym of formosae Lin & Wu (see note under the latter name); of brevispinosus: Wang, M. 2003: 428.

Worker
Wang (2003) - TL 3.00-4.26, HL 0.73-1.04, HW 0.68-1.04, CI 93-102, SL 0.64-1.06, SI 94-108, EL 0.14-0.19, PW 0.48-0.68, AL 0.76-1.10, PPW 0.21-0.27, PPL 0.18-0.30, PPI 86-113 (n = 100).

Mandibles generally rather smooth but sometimes with a few longitudinal rugae. Dentition of the masticatory margin of mandible arranged as: the strongest apical + the second strongest preapical + a long diastema + two small teeth of similar size (or a broad tooth with two points). Basal margin of mandible almost straight, lacking a distinctly curved lobe or tooth. Clypeus with a median longitudinal carina that is sometimes interrupted. Anterior clypeal margin with a median denticle and two to three others on each side. Ventral center of clypeus usually with an acute tooth, but sometimes this tooth somewhat low and broad. Palp formula 1,3. Frontal carinae strong, extending to the level of the posterior margins of eyes. Antennal scrobes indistinct, but in some specimens shallow scrobal areas present lateral to the frontal carinae. Frontal lobes very weak; thus, the antennal articulations are almost entirely exposed. Antennal scapes, when lying on the dorsal head, slightly surpassing the occipital margin of head. Eye usually containing seven to eight ommatidia in the longest row. Pronotum armed with a pair of toothlike armaments that vary in length, approximately from 0.06 to 0.10. Propodeum with a pair of triangular teeth or short spines varying from 0.04 to 0.12. Metapleural lobe subtriangular or with a somewhat rounded apex. Shape of petiole varying: In some populations, the anterior face of the petiole node in profile is almost inseparable from the upper surface of the peduncle, but in other populations, the anterior face of the petiole node is distinct from the upper surface of the peduncle. Anterodorsal angle of petiole node higher than the posterodorsal. Postpetiole in profile convex dorsally, in dorsal view broadening from front to back. Density and intensity of cephalic sculpture variable: The dorsum of head is covered fully with coarse forveolate-reticulate sculpture in type series, but with rugoreticulum in the some other series and sometimes with foveolate-reticulate sculpture only behind the eyes. Dorsum of the alitrunk showing similar sculptural variation but usually possessing a few longitudinal coarse carinae. Petiole, postpetiole, and gaster smooth and shining. Dorsal surfaces of head and alitrunk with numerous erect or suberect hairs. Two pairs of hairs usually present bilaterally on the dorsum of petiole node. Usually, a pair, but sometimes two to three pairs, of hairs on the dorsum of postpetiole. 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. Color reddish-brown to blackish-brown.

Queen
Wang (2003) - TL 3.42-4.81, HL 0.82-1.09, HW 0.79-1.10, CI 93-106, SL 0.76-1.06, SI 93-101, EL 0.20-0.27, PW 0.66-0.89, AL 0.94-1.30, PPW 0.24-0.32, PPL 0.24-0.33, PPI 90-111 (n = 16).

General shape as with normal caste differences from the conspecific worker, pronotum unarmed; other characters similar to worker.

Ergatoid. This caste was reported (Onoyama, 1976; see also Yamane and Terayama, 1999).

Male
Wang (2003) - Two male specimens, together with 31 workers and six queens, constitute a series, collected in Indonesia (SE Celebes, 1-2 km E of Wolasi, 42 km S. Kendari, ca. 350 m), by W. L. Brown, and each of the two males was originally mounted, respectively, with a worker on the same pin: TL 3.10, 3.36; HL 0.60, 0.62; HW 0.61, 0.62; CI 102, 105; SL 0.21, 0.22; SI 35, 39; HWE 0.77, 0.80; EL 0.31, 0.32; P\V 0.78, 0.84; AL 1.06, 1.16; PPW 0.21, 0.21; PPL 0.22, 0.22; PPI 95, 9.5 (n = 2).

Head, including the eyes, distinctly broader than long. Clypeus convex, without a median longitudinal carina. Palp formula 1,3. Frontal carinae weak and short, just reaching the level of the posterior margins of antennal insertions. Maximum diameter of the median ocellus 0.10 to 0.11. On the mesonotum, notauli pronounced, forming a Y shape; parapsidal furrows indistinct. Scuto-scutellar sulcus with 12 to 13 narrow longitudinal ridges. Middle and hind tibiae without any spurs. Propodeum slightly tuberculate, lacking teeth or spines. Metapleural lobe with a somewhat rounded apex. Petiole node in profile low and rounded dorsally, with a fairly long anterior peduncle. Postpetiole in profile low and rounded dorsally and in dorsal view slightly longer than broad. Dorsum of head smooth and shining. Alitrunk smooth and shining, except for those marked sutures. Petiole, postpetiole, and gaster smooth and shining. All dorsal surfaces with abundant erect or suberect hairs. Scapes and tibiae with numerous erect or suberect hairs. Body reddish-brown; funicular segments of antennae light-yellow and wings slightly infuscated. In general, the male of P. brevispinosus is extremely similar to the males of both Pristomyrmex quadridens and Pristomyrmex sulcatus.

Type Material
Wang (2003):

Syntype workers and male, Sumatra: Mt. Singalang, Luglio, 1878 (O. Beccari) [syntype workers (, NMMV, ) examined].

Pristomyrmex yaeyamensis Holotype worker, Japan: Okinawa Pref., Yaeyama Is., Iriomote-jima, 7.viii.l98.5 (K. Kinomura).

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