Pristomyrmex punctatus

Wang (2003) - It appears that P. punctatus occurs in open habitats. My impression stems from field experience in China as well as from data associated with specimens. This species lacks a normal queen caste; mature colonies usually contain several thousand workers and a few males, but ergatoid queens are rarely found. Eggs are normally laid by workers and can develop into workers or males. Ergatoid queens, when present, can also lay eggs. Brood production begins in April and lasts until the end of September. Young workers remain inside the nest and lay eggs. Older workers forage but lose the ability to lay eggs. Nests are often constructed in leaf litter from June to August but in the soil around trees from September to October. Sometimes arboreal nests are constructed on dead standing trees or in partially dead parts of living trees. The nest entrances of the arboreal nests and those under rotten wood are often covered with soil particles. See the following references for information on these and other aspects of the biology of P. punctatus (How et al., 1984; Mizutani, 1980, 1982; Tsuji, 1988a, 1988b, 1988c, 1990a, 1990b, 1994, 1995; Tsuji and Ito, 1986).

Identification
Wang (2003) - Eyes with eight or more ommatidia in the longest row; pronotum unarmed; propodeal spines straight, and long, much longer than the distance between their bases; dorsal surfaces of both head and alitrunk covered fully with rugoreticulum; dorsum of petiole node with two or more pairs of hairs.

The separation of P. punctatus from both Pristomyrmex divisus and Pristomyrmex pulcher is summarized in the discussions of both P. divisus and P. pulcher. The following characters can be used to separate the workers of P. punctatus from those of its closest relative, Pristomyrmex rigidus: P. punctatus - Dorsum of petiole node with two or more pairs of hairs. Tooth absent or inconspicuous from basal margin of mandible. Dorsal surfaces of head and alitrunk, and the sides of petiole and postpetiole more finely sculptured. Propodeal spines relatively slender. Clypeus with a median longitudinal carina that meets the anterior clypeal margin. Dorsum of alitrunk in dorsal view, marginated, and more or less depressed. Ventral surface of clypeus with a curved ruga but lacking distinct toothlike prominences. P. rigidus - Dorsum of petiole node only with a single pair of hairs. In type specimens, a strongly prominent tooth present on basal margin of mandible. Dorsal surfaces of head and alitrunk, and the sides of petiole and postpetiole more coarsly sculptured. Propodeal spines relatively robust. Median clypeal carina often not reaching the anterior clypeal margin. Dorsum of alitrunk in dorsal view, convex. Ventral surface of clypeus usually with two minute toothlike prominences.

In addition, an ergatoid queen caste is present in P. punctatus but not seen in P. rigidus, while a normal queen caste exists in P. rigidus but has not been found in P. punctatus.

A member of the Punctatus species group

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, New Guinea, Philippines, Singapore. Oriental Region: Laos, Taiwan, Thailand, Vietnam. Palaearctic Region: China, Democratic Peoples Republic of Korea, Japan, Republic of Korea.

Biology
Wang (2003) - P. punctatus originated in the subtropics or tropics of Asia, as its three close relatives, P. rigidus, P. pulcher, and P. divisus, are restricted to Sumatra, Malaysia, Brunei, Thailand, and the Philippines, respectively. But P. punctatus has a very large range, from New Guinea, Indonesia to Malaysia, Thailand, and then north to China and Japan, indicating its exceptional dispersal ability and tolerance of temperate climates. Pristomyrmex punctatus has shown some tendency for dispersal by humans. Interception records from ports in North America suggest that human commerce may have played a role in this species' spread in temperate Asia.

The chromosome numbers of this species, reported by Imai (1966) and Itow et al. (1984), are 211 (diploid) = 24 in the cerebral ganglion cells of the workers and 11 (haploid) = 12 in the spermatocytes of the males. The larva of this species was described by Wheeler and Wheeler (1954).

I have also examined 11 workers collected at the two entry ports of the United States (USNM): nine of them, by Harley and Albrecht, on November 20, 1928, from Philadelphia, Pennsylvania, in lily bulbs imported from Japan; the other two specimens, by J. F. Byrnes, on September 25, 1967, from Anchorage, Alaska, on Gerberia sp. imported from Japan. It appears, however, that P. punctatus has not yet become established in the United States (Cover, personal communication).

Yamada and Eguchi (2016) reported a colony of P. punctatus was found under a concrete block on the ground in a green tract of the Minami-Osawa Campus of Tokyo Metropolitan University. The colony contained more than 100 males. Some of these individuals subsequently served as the source material for their description of the male genitalia of this species. The finding and description of these males are important, in part, as this species can reproduce parthenogenetically. Despite this, the male genitalia does appear to be fully functional in this species when males are produced.



Myrmechochory
Zhu and Wang (2014) found this species was an important disperser of "Corydalis wilfordii and C. racemosa (Papaveraceae) seeds in a subtropical evergreen forest at the Jiugongshan mountain (Hubei Province, China). The seed size of C. wilfordii is larger than that of C. racemosa, while the elaiosome/seed mass ratio of C. wilfordii is greater than that of C. racemosa. Being the mutual ant dispersers of the two Corydalis taxa, Pristomyrmex pungens (=Pristomyrmex punctatus) (with mass recruitment mode, i.e. to recruit a large number of ants to remove seeds when one ant found seed) and Prenolepis sphingthorax (=Nylanderia flaviabdominis) (with simple cooperative recruitmen mode, i.e. to recruit 5-30 ants to remove seeds when one ant found seed) played a varied role in seed dispersal of two plants. Pristomyrmex pungens carried about 44% of the C. wilfordii seeds transported by it to the nests, with the average dispersal distance of 1.85 m and the removal number of seeds per hour of 43.8, while the rest seeds were removed elaiosomes in situ and/or on the way to the nest. Both Pristomyrmex pungens and Prenolepis sphingthorax carried the all seeds of C. racemosa to the nests, with the average dispersal distance of 6.27 m and 6.65 m, and removal number of seeds per hour of 34.2 and 10.6 respectively. The results suggested that seed removal rate of ant with mass recruitment was higher than that of ant with simple cooperative recruitment. The seed dispersal distance and short-term seed fate differed between the two studied plants, depending on ant foraging strategies and behavior and seed characteristics."

Zhu and Wang (2018) reported on the responsiveness of myrmecochorous ants to leaf volatiles of Corydalis and the potential role of these chemicals in attracting ants to a plant's seeds. "Although the myrmecochorous seeds can be found and then transported by ants because of the attached elaiosome, the results of our study indicated that leaf volatiles of some myrmecochorous Corydalis species can function as an attractant for ant dispersers, and such attractiveness in turn enhances the seed retrieval. It suggests that leaf volatiles of some Corydalis species may be one of several factors shaping the ant-seed dispersing interactions. Further research is needed to identify the chemical basis of volatiles that trigger ant foraging activity, and to assess to what extent the seed dispersal of Corydalis species depend on leaf volatiles."

Morphology
Male Genitalia - Yamada and Eguchi (2016) - Pygostyle digitiform with 3 – 8 long setae in its apical third (Fig. 2). Abdominal sternite IX subhexagonal in outline (Fig. 3); spiculum (anterior apophysis of the sternite IX, Sp in Fig. 3) short; anterior margins meeting in an obtuse angle basal to the spiculum; anterolateral sternal corners weakly produced anterolaterally; lateral margins slightly concave; posterolateral sternal corners somewhat produced anterolaterally; posteromedian part ventrally with long setae. Genital capsule longer than wide. Cupula wider than long, weakly constricted anteriorly (Fig. 4), with its mesoventral part shortened anteroposteriorly as a transverse bridge (the anterior and posterior margins of cupula indicated by black dashed line in Fig. 4). Telomere distinctly differentiated from basimere by ventral notch (the notch indicated by dashed line in Fig. 5); oblique carina present on lower of basimere (BmC in Fig. 5); gonostipital arm (median anteroventral extension of the basimere indicated by red dashed line in Fig. 4 and Ga in Fig. 4 and 5) in ventral view almost as long as basal width, with its lateral and mesal margins converging and forming an acute apex; telomere in lateral view almost as long as high, with setae on the outer surface of its posterior part (Fig. 6); ventral ridge of volsella with setae (Fig. 5); cuspis in lateral view roundly lobate and short, not reaching posterior margin of digitus (Fig. 7); digitus in lateral view claw-shaped, entirely hooked ventrad (Fig. 7); very short setae with distinct sockets scattered ventrally on digitus. Valviceps in lateral view with posterior apex hooked ventrad, anteroventral corner not produced; ventral margin with 9 – 13 denticles (Fig. 8); foveae (recognized as tunnels running inside valviceps) sparsely present on apical and ventral area of valviceps (some of apical foveae probably with short setae but obscure in optical microscope observation); valvura directed dorsoanterolaterally (Va in Fig. 9); lateral apodeme produced ventrolaterally (Lp in Fig. 9), forming wing-like structure which hold basal part of volsella in genital complex; penisvalva membrane densely spinate (Pvm in Fig. 9).

Nomenclature

 *  punctatus. Myrmica punctata Smith, F. 1860b: 108 (w.) INDONESIA (Batjan I.). Wang, M. 2003: 412 (ergatoid q.). Combination in Pristomyrmex: Mayr, 1886c: 361. Senior synonym of pungens (and its junior synonym japonicus): Wang, M. 2003: 410.
 * pungens. Pristomyrmex pungens Mayr, 1866b: 904, pl. 20, fig. 13 (w.) WEST MALAYSIA. Wheeler, W.M. 1928d: 114 (m.); Wheeler, G.C. & Wheeler, J. 1954c: 131 (l.); Imai, 1966: 119 (k.). Senior syonym of japonicus: Viehmeyer, 1922: 207. See also: Itow, Kobayashi, et al. 1984: 87; Lin & Wu, 1998: 94. Junior synonym of punctatus: Wang, M. 2003: 410.
 * japonicus. Pristomyrmex japonicus Forel, 1900e: 268 (w.) JAPAN. Junior synonym of pungens: Viehmeyer, 1922: 207.

Type Material
Myrmica punctata

Two worker syntypes in. Labelled “Bac 24.” (= Batjan I.).

Wang (2003):

Syntype workers, Indonesia: Bachian I. (A. H. Wallace) [examined].

Pristomyrmex pungens Holotype worker, Malaysia: Malacca (?) (NHPS) [examined].

Pristomyrmex japonicus Syntype worke rs, Japan: Osaka (K. Yamada) [examined].

Worker
Wang (2003) - TL 2.62-3.22, HL 0.70-0.84, HW 0.68-0.84, CI 94-105, SL 0.78-0.86, SI 102-118, EL 0.1.5-0.18, PW 0.48-0.56, AL 0.70-0.84, PPW 0.24-0.27, PPL 0.17-0.20, PPI 126-163 (11 = 70).

Mandibles usually with a few fine longitudinal rugae but smooth near the masticatory margin. Dentition of the masticatory margin of mandible: the strongest apical tooth + the second strongest pre apical + a long diastema + a broad basal tooth (or two small basal denticles). Basal margin of mandible rather straight, lacking a distinct tooth. Clypeus shieldlike, more or less depressed, with a median longitudinal carina extending posteriorly through the frontal area. In some specimens, a few short weak rugae present on each side of the median carina of the clypeus. Anterior clypeal margin equipped with a row of denticles, but sometimes median denticle indistinct or absent or becoming a broad-truncated lobe. Lateral portions of clypeus reduced to margins, so that the antennal fossae reach the anterior clypeal margin. Ventral surface of clypeus usually with a curved ruga. Palp formula 5,3. Frontal carinae distinct, extending to the level of the posterior margins of eyes. Antennal scrobes weak. Frontal lobes almost completely absent; thus, the antennal articulations are entirely exposed. Antennal scapes, when lying on the dorsal head, surpassing the occipital margin of head by one-sixth to one-fifth of their length. Eyes large, with eight or more ommatidia in the longest row. Occipital margin feebly concave. Dorsum of the alitrunk in dorsal view marginated and more or less depressed. Pronotum unarmed. Propodeal spines long, acute, but slender. Metapleural lobes dentiform and acute. Petiole node in profile wedge-shaped, with a triangular apex. Postpetiole in profile convex dorsally; in dorsal view transverse-rectangular, much broader than long, and also broader than the petiole. Dorsal surfaces of head and alitrunk as well as sides of pronotum cove red fully with rugoreticulum, but scrobal areas with only several transverse rugae. Sides of the rest of the alitrunk with numerous irregular rugae. Sides of petiole and postpetiole usually with a few fine longitudinal rugae; sometimes rugae very weak and broken. Gaster unsculptured. Dorsal surfaces of head and alitrunk with numerous erect to suberect long hairs. Two (or more) pairs of hairs present, respectively, bilaterally on the dorsums of petiole node and postpetiole, of which usually a pair shorter and the other pair longer. First gastral tergite lacking erect or suberect hairs. A few pairs of long, forward-projecting hairs present near the anterior clypeal margin that are symmetrical on the two sides of the midpoint. Scapes and tibiae with numerous erect to suberect short hairs. Color reddish-brown, but sometimes the gaster much darker or the appendages slightly lighter.

Queen
Wang (2003) – Ergatoid. TL 3.60, 3.72; HL 0.86, 0.88; HW 0.94, 0.94; CI 107, 109; SL 0.89, 0.91; SI 97, 97; EL 0.23, 0.23; PW 0.66, 0.68; AL 0.94, 0.96; PPW 0.31, 0.32; PPL 0.23, 0.24; PPI 133, 135 (11 = 2).

Closely resembling the worker in the structure of mandibles, clypeus, petiole, postpetiole and gaster and also in sculpture, color, and pilosity. But the head with three ocelli; eyes large r; pronotum and propodeum narrower than those of worker; mesonotum more convex; an impression present at the approximate positions of promesonotal suture and of metanotal groove, respectively; propodeal spines stronger than in worker. Wing absent, but the rudimentary vestige of a wing is present on the each lateral margin of the mesonotum.

Male
Wang (2003) - TL 3.22, HL 0.60, HW 0.57, CI 9,5, SL 0.18, SI 32, HWE 0.79, EL 0.32, PW 0.74, AL 1.04, PPW 0.26, PPL 0.17, PPI 153 (11 = 1; one specimen [MCZC] collected from Nara, Japan, by Silvestri on July 21, 1925, was examined).

Head, including the eyes, broader than long. Clypeus transverse, with a median short carina. Frontal area with a median longitudinal carina. Frontal carinae short, slightly beyond the posterior margins of antennal sockets. Palp formula 5,3. On the mesoscutum, notauli pronounced, forming a Y shape; parapsidal furrows superficially impressed. Propodeum with a pair of teeth. Metapleural lobes subtriangular. Middle and hind tibiae each with a simple spur. Petiole node wedge-shaped, with a triangular apex; dorsum of petiole peduncle forming a declivity that reaches the top of the node. Postpetiole in profile rounded dorsally, in dorsal view transverse-rectangular and distinctly broader than long. Dorsum of head smooth and shining, except for few short rugae present behind the posterior margin of clypeus. Pronotum and mesoscutum smooth, except for those marked sutures, but mesoscutellum and propodeum sculptured with several longitudinal algae. Sides of petiole with a few rugae. All dorsal surfaces with abundant erect or suberect hairs, but hairs on the legs and on the scapes somewhat appressed. Colour reddish-brown; wing light-yellow.