Pristomyrmex sulcatus

This is a rather wide ranging species, being found from India east to Vietnam. In India specimens have been collected by Winkler’s extractor from an undisturbed dense secondary forest. The thickness of leaf litter was about 4 inches. The floor of the forest receives limited sun light. The maximum temperature of the area is 28°C, minimum -1°C and rainfall 325cm per annum (Bharti & Singh, 2014).

Identification
Wang (2003) - Ventral surface of clypeus with a strongly prominent tooth at the center; pronotum with a pair of moderately long spines (0.14-0.20), usually longer than propodeal armaments (0.07-0.13); dorsum of head with foveolate-reticulate sculpture or rugoreticulum; petiole node lacking foveolate punctures; first gastral tergite lacking erect or suberect hairs.

The separation of P. sulcatus from Pristomyrmex costatus is provided under P. costatus. The worker of P. sulcatus differs from that of Pristomyrmex hirsutus by its petiole node with the anterodorsal angle higher than the posterodorsal and its first gastral tergite lacking erect or suberect hairs. The worker of P. sulcatus differs from that of Pristomyrmex modestus by its petiole node higher than long and lacking distinct foveolate punctures. The worker of P. sulcatus differs from that of Pristomyrmex occultus by its masticatory margin of the mandible possessing at most four teeth and its propodeal armaments not longer than the pronotal spines. The queen of P. sulcatus differs from that of Pristomyrmex bicolor by possessing a strongly prominent tooth on the ventral center of the clypeus.

Key to Pristomyrmex workers

Distribution based on Regional Taxon Lists
Indo-Australian Region: Malaysia. Oriental Region: India, Myanmar, Nepal, Thailand, Vietnam. Palaearctic Region: China.

Nomenclature

 *  sulcatus. Pristomyrmex brevispinosus subsp. sulcatus Emery, 1895k: 464 (w.q.) MYANMAR. Wang, M. 2003: 471 (m.). Raised to species: Wang, M. 2003: 469.

Wang (2003) - The taxonomic status of “sulcatus” is somewhat complicated. The syntype workers of Pristomyrmex brevispinosus sulcatus differ from those of Pristomyrmex brevispinosus by possessing a pair of fairly long pronotal spines (0.15-0.16), as compared with a pair of teeth (0.06) in the latter. However, after examining all available material, I find that the length of the pronotal armaments is continuously variable (from 0.06, as in the syntypes of P. brevispinosus, to 0.20, as in the specimens from Khao Yai Nat. Park, Thailand). The syntype workers of “sulcatus”, in fact, are intermediates between the two extreme ends (i.e., in one extreme, the pronotal teeth are slightly shorter than or about as long as the propodeal teeth; in the other extreme, the pronotal spines are two to three times as long as the propodeal armaments. I keep “sulcatus” as a valid name (i.e., raise it to the rank of species instead of assigning it as a junior synonym of P. brevispinosus) because more ecological work must be done before the status of “sulcatus” becomes clarified. With this tentative proposal, P. sulcatus comprises those populations with pronotal spines (ca. 0.14-0.20), distributed in Pahang (1,300-1,720 m), Malaya, and in northwest and central Thailand, Burma, Nepal, and southwest China. Pristomyrmex brevispinosus comprises populations with toothlike pronotal armaments (ca. 0.06-0.10), occurring in Pahang (1,250 m), Malaya, and Trang Province of South Thailand (07.55°N) and in the Philippines, Taiwan, and Japan. In other words, P. sulcatus may be a northerly replacement of P. brevispinosus along the Malay peninsula.

Worker
Wang (2003) - TL 3.98-4.74, HL 0.98-1.16, HW 0.96-1.10, CI 93-105, SL 1.02-1.15, SI 101-111, EL 0.14-0.19, PW 0.64-0.75, AL 0.98-1.18, PPW 0.26-0.30, PPL 0.26-0.32, PPI 90-100 (n = 30).

Mandibles usually with some longitudinal rugae, varying from superficial to distinct. Masticatory margin of mandible with four teeth arranged as the strongest apical + the second strongest preapical + a long diastema + two small basal teeth of similar size that are fused together. Basal margin of mandible almost straight, lacking a distinctly convex lobe or tooth. Clypeus with a median longitudinal carina. Anterior clypeal margin with a median denticle and two to three others on each side; but sometimes two lateral denticles are fused into a larger tooth. Ventral center of clypeus with a strongly prominent tooth. Palp formula 1,3. Frontal carinae strong, extending to the level of the posterior margins of eyes, forming the dorsal margins of the shallow antennal scrobes. 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. Eyes usually containing six to seven ommatidia in the longest row. Profile shape of alitrunk and pedicel segments. Pronotum with a pair of spines, vmying in length from 0.14 (in the type series) to 0.20. Propodeum with a pair of teeth or short spines varying from 0.07 to 0.13. Metapleural lobes subtriangular or somewhat rounded. Petiole node in profile high, with a fairly long anterior peduncle; its anterodorsal angle is on a higher level than the posterodorsal. Postpetiole in profile rounded dorsally, in dorsal view broadening from front to back, about as long as or slightly longer than broad. Dorsum of head, except for the scrobal areas where rugae are somewhat weak, with course rugoreticulum or dense alveolate punctures. Similar but slightly sparse sculpture present on the dorsum of alitrunk and often on the two sides of pronotum. Petiole, postpetiole, and gaster smooth and shining. Dorsal surfaces of head and alitrunk with numerous erect or suberect hairs. Usually, two pairs of hairs present on the dorsum of petiole node and one to two pairs 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 hairs. Color reddish-brown.

Queen
Wang (2003) - SL1.01-1.12, SI 98-101, EL 0.22-0.26, PW 0.77-0.90, AL 1.16-1.30, PPW 0.28-0.32, PPL 0.29-0.32, PPI 97-100 (n = 4)

General shape with normal caste differences from the conspecific worker; pronotum usually unarmed but rarely with a pair of minute spines. Other characters similar to worker. The queens of P. sulcatus are almost indistinguishable from those of P. brevispinosus at present.

Male
Wang (2003) - One male specimen (MCZC), collected in Thailand (Nakhon Ratchasima Prov., Khao Yai Nat. Park, 750 m, hill forest) by I. Burikam and W. L. Brown, was originally mounted with a worker on the same pin; it has the following measurements: TL 3.90, HL 0.58, HW 0.61, C1 10.5, SL 0.22, S1 36, HWE 0.83, EL 0.33, PW 0.82, AL 1.18, PPW 0.24, PPL 0.24, PP1 100 (n = 1).

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. On the mesonotum, notauli strongly marked, forming a Y shape; parapsidal furrows absent. Scuto-scutellar sulcus rather broad, with 10 ridges that expand at the upper end. Propodeum slightly tuberculate, lacking teeth or spines. Metapleural lobes subtriangular. Middle and hind tibiae without any spurs. Petiole node in profile low, with a fairly long anterior peduncle. Postpetiole low, in dorsal view about as long as broad. Dorsum of head generally smooth and shining but with a median longitudinal carina present on the frontal area and several short rugae on the posterior clypeal margin. 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 legs with erect or suberect short hairs. Body reddish-brown; funicular segments of antennae white and wings slightly light-yellow. At the present, the male of Pristomyrmex sulcatus is almost indistinguished from the males of Pristomyrmex brevispinosus and Pristomyrmex quadridens.

Type Material
Wang (2003) - Syntype workers, queen, Burma: Carin Cheba, 500 to 1,000 m, xii.1887 (L. Fea) [syntype workers(, NHMV) examined].