Protanilla jongi

Hsu et al. (2017) collected a colony of this species, maintaining and observing it in the laboratory for numerous months (see biology section below).

Identification
Hsu et al. (2017) - Protanilla jongi can be easily distinguished from other Protanilla species by the combination of the following characters: mandibles with a small blunt denticle at the ventral margin, postpetiolar sternite with a right-angled anteroventral corner in lateral view, postpetiole broadly attached to abdominal segment IV and with a bell-shaped outline in dorsal view.

Some variation in the shape of the petiole and postpetiole were observed among the holotype and paratype workers: anterior face of the petiole (above the short peduncle) sometimes slightly concave; the angular anteroventral corner of postpetiolar sternite sometimes slightly produced.

Distribution based on Regional Taxon Lists
Oriental Region: Taiwan.

Biology
Hsu et al. (2017) A colony was collected from the Fenghuang Education Area at an altitude of 840 m. The area is a tea garden with several types of vegetation, mainly Cunninghamia lanceolata, Schima superb, bamboo, and various ferns. It is near secondary forest which mainly consists of Acacia confuse. The colony was found nesting in a built chamber at a depth of approximately 20 cm in soil, covered by a stone.

The P. jongi colony was observed in our laboratory for 6 months (a colony of Protanilla lini was also collected and observed). All of the members demonstrated the behavior noted by Wilson and Hölldobler (1990), which is consistent with those of typical trap-jaw ants (e.g. Odontomachus and Anochetus). Although mandibles of Protanilla workers are not linear in shape, they are able to open to 180 degrees and strike during predatory interactions. This behavior was also recorded in P. wallacei a few times in the laboratory (F. Ito, personal communication). Furthermore, we observed that Protanilla workers locked their mandibles in the striking position when guarding their nest entrances in the laboratory. The guarding behavior was also recorded in Leptanilla japonica by Masuko (1990), who noted that most of the workers stood near the brood pile facing outward, with the anterior half of the body raised, the forelegs suspended in the air, and the mandibles open. However, whether Leptanilla could quickly snap their mandibles as those of Protanilla and other trap-jaw ants was not mentioned in the previous articles.

In our laboratory observations, we provided various types of prey (centipedes, cockroaches, meal worms, termites, springtails, and woodlice). Only certain types of centipedes were accepted; specifically, they appeared to prefer geophilomorph centipedes that were approximately 3–4 cm in length. Smaller and larger geophilomorph centipedes were also acceptable, but the members were unable to finish those exceeding 4 cm. We removed them to avoid a sanitation problem in the nest. This observation is similar to the ecological notes in Ogata et al. (1995), which reported that Leptanilla taiwanensis larvae were found in the field feeding on a geophilomorph centipede approximately 4 cm in length; Masuko (1990) also demonstrated this phenomenon, indicating that L. japonica exclusively fed on geophilomorph centipedes ranging from 1–2 cm in the laboratory (but whether centipedes larger than 2 cm were provided is unclear). However, "P. wallacei" was observed to feed on Occasjapyx diplurans (Billen et al. 2013). Further field and laboratory observations are required to determine the degree to which Protanilla and other Leptanillinae specialize on centipedes.

In our captive colonies, when a live centipede was encountered, the workers grabbed the appendages of the centipede by quickly snapping their mandibles and stinging the victim. The centipede was paralyzed within a few minutes and transported back to the nest, where it was consumed by numerous larvae that were carried and attached to the prey by the workers. We did not observe the situation discussed in Masuko (1990), where L. japonica workers carried the larvae toward the paralyzed prey rather than bringing the prey back to the nest.

However, whether the synchronized larval development and larval hemolymph feeding behaviors in L. japonica also appear in Protanilla species remains unclear. In our observations, we did not record the gynes of either species feeding on larvae. Nevertheless, during the 6-month observation of the P. lini colony, we did note the larvae of different instars present in the colony at the same time. More living material of Protanilla species is needed for the further examination of larval biology.

In addition, strong and distinct odors spread when the colony was excavated and even when undisturbed in the laboratory. However, it remains unclear whether the odor was produced by adults or larvae.

Nomenclature

 *  jongi. Protanilla jongi Hsu, P.-W. et al. 2017: 119, figs. 1-4 (w.q.) TAIWAN.

Worker
Holotype worker: HL 0.80, HW 0.69, CI 86, SL 0.74, SI 107, ML 0.47, PW 0.51, WL 1.24, PNL 0.37, PNH 0.45, PNW 0.35, PPNL 0.42, PPNH 0.38, PPNW 0.37; Paratype workers (n=9): HL 0.77–0.84, HW 0.66–0.75, CI 85–89, SL 0.67–0.75, SI 97–107, ML 0.43–0.50, PW 0.43–0.54, WL 1.17–1.33, PNL 0.31– 0.39, PNH 0.43–0.49, PNW 0.31–0.37, PPNL 0.37–0.44, PPNH 0.35–0.41, PPNW 0.36–0.39; Paratype queen: HL 0.73, HW 0.62 , CI 85, SL 0.68, SI 110, ML 0.37, PW 0.58, WL 1.44, PNL 0.37, PNH 0.52, PNW 0.39, PPNL 0.46, PPNH 0.44, PPNW 0.44.

Holotype worker: Body brownish-yellow. In full-face view, head longer than wide, slightly narrow anteriorly; posterior margin straight; lateral margins convex. Eyes absent. Clypeus in full-face view with a bell-shaped outline; anterior margin concave, without depressed middle strip. Mandibles long and triangular; masticatory margin slightly crenulate, with approximately 20 peg-like teeth; apical 1/3 denticulate and without peg-like teeth. A longitudinal groove running along the dorsolateral margin of mandible, traversing the width to inner margin at 1/3 the length to apex, just before the preapical series of denticles. A series of long stout hairs on masticatory margin of mandibular apical portion, with the foremost one stoutest. In lateral view, mandible strongly down-curved apically, with a small blunt denticle at inner ventral face, 1/3 the length to base. Antennae 12- segmented; scape long, slightly exceeding posterior margin of head; segments 2–3 somewhat conical and longer than wide; segments 4–11 nearly as long as wide; terminal segment twice as long as wide. Mesosoma slender. Pronotum in dorsal view round, twice as broad as mesonotum, in lateral view with a convex dorsal outline. Promesonotal groove distinct dorsally and laterally. Mesonotum thin, in dorsal view narrow posteriorly, in lateral view with a straight dorsal outline. Metanotal groove depressed with several short longitudinal notches. Propodeum in dorsal view oval, with posterior half round, in lateral view with a convex dorsal outline and propodeal spiracle in the middle lower part above bulla of metapleural gland.

Petiolar node in dorsal view round, in lateral view straight anteriorly and slightly convex dorsally, forming a round posterodorsal corner and a clearly differentiated posterior face sloping down to the articulation with postpetiole; anterolateral part just above the anterior short peduncle forming a small projection. Subpetiolar sternite in lateral view approximately 1/4 as high as petiole height, narrow posteriorly, with a lobe-like subpetiolar process anteroventrally. A circular transparent fenenstra in the center of that process. Presclerites of postpetiole constricted to helcium, attached to almost the center of the anterior face of postpetiole at approximately 45 degrees. Postpetiole broadly attached to abdominal segment IV, without any free posterior face above the articulation with abdominal segment IV. Postpetiole in dorsal view with bell-shaped to trapezoidal outline, broad posteriorly, in lateral view with a round anterior face and a slightly convex dorsal outline above the articulation with petiole; anteroventral corner of postpetiolar poststernite forming a right angle. Postsclerites of postpetiole and presclerites of abdominal segment IV, when the articulation is outstretched, forming a continuously outline. Presclerites of abdominal segment IV coarsely sculptured; pretergite narrow; presternite well-developed and bulging. An inconspicuous narrow girdling constriction between pre- and postsclerites of abdominal segment IV. In dorsal view, anterior margin of posttergite of abdominal segment IV slightly concave. In lateral view, dorsal and ventral margins of postsclerites of abdominal segment IV forming a continuous outline which is slightly convex, and narrow anteriorly, but never forming a deep and narrow notch between the posttergite and poststernite at the anterior margin. Sting long, exceeding half the length of gaster.

Queen
Paratype female (queen): Body brown, darker than that of worker. In full-face view, head slightly longer than wide; sides convex; posterior margin straight. Compound eyes large, located in the center of the side of head. Ocelli present. Clypeus same shape as in workers. Mandibles similar to worker, slightly more robust and less down-curved in lateral view. Antennae similar to worker. Mesosoma well developed. Pronotum in dorsal view approximately as long as scutum, in lateral view with a convex dorsal outline. Scutum in dorsal view shield-shaped, somewhat triangular, in lateral view with a flat dorsal outline. Scutellum in dorsal view small, half the length of scutum, in lateral view with a convex dorsal outline. Propodeum in dorsal view somewhat trapezoidal, with posterior face convex, in lateral view with a round dorsal outline. Propodeal spiracle large, at middle lower part above bulla of metapleural gland, which is considerably more developed than that of workers. Petiole and postpetiole in both dorsal and profile view same shape as in workers, but postpetiole in lateral view with a more convex dorsal outline and a more produced anteroventral corner. Presternite of abdominal segment IV less prominent than those of workers. Abdominal segment VI broadly attached to postpetiole, in dorsal view anterior margin concave.

Type Material
Holotype (worker): Taiwan, Nantou, Fenghuang Education Area, (23°43.763'N, 120°47.313'E), alt. 840 m, by hand-collecting, 05. III. 2016, Po-Cheng Hsu leg. (NMNS). Paratypes: 1 ♀ (worker): same location as the holotype, by Winkler extraction method, 28.XI.2015, Po-Wei Hsu leg.; 8 (worker), 1 (queen): same data as the holotype (1 worker at ; 2 workers and queen at NCUE; 2 workers at ; 2 workers at ; 2 workers at )

Etymology
The new species is named after Dr. Jaw-Jinn Jong, an entomologist from Taiwan.