Leptanilla taiwanensis

Known from a few collections, the most recent of which were from subterranean pitfall traps.

Identification
Ogata et. al. (1995) - The simple clypeus with shallow median incision in the anterior margin also occurs in Leptanilla oceanica from the Ogasawara Islands and Leptanilla vaucheri from Morocco. But this new species is separable by the combination of the characters of 3 teeth on the mandibles, the less-produced median portion of the clypeus, the subglobular petiole, the globular postpetiole and the anteriorly narrowed first gastral segment.

Distribution based on Regional Taxon Lists
Oriental Region: Taiwan. Palaearctic Region: China.

Biology
Ogata et. al. (1995) – A colony was found in clay soil about 15 cm in depth by a roadside cutting. In the nest many larvae were found feeding on a geophilomorph centipede, which was identified as Mecistocephalus  sp. through the courtesy of K. Shinohara. The larvae put their heads into the body of the centipede via its pleura. Although the posterior half of the centipede’s body had been consumed by the larvae, the total length was estimated about 4cm based on its head size (Shinohara, pers. comm.). In the laboratory colonies of Leptanilla japonica, Masuko (1990) also observed that the ant preferably hunted and consumed geophilomorph centipedes. These field and laboratory observations suggest that Leptanilla is specialized on this group of centipedes.

Man et al (2017) - Using a subterranean pitfall trap, we collected 116 workers of Leptanilla taiwanensis from nine sample plots in Beijing: plots 2 to 4 - northwest suburb of Beijing, mountainous forested area close to a road and surrounded by farmland and plots 5 to 10, urban parks and green belts along roads significantly disturbed by human activities. Geographic coordinates and elevation of the sites where L. taiwanensis were collected are as follows. Site 2: 40°22′26″N, 115°58′18″E, 550 m; Site 3: 40°8′59″N, 116°1′32″E, 167 m; Site 4: 40°1′13″N, 115°52′5″E, 269 m; Site 5: 40°2′7″N, 116°15′8″E, 68 m; Site 6: 40°0′18″N, 116°18′17″E, 51 m; Site 7: 39°57′12″N, 116°12′49″E, 60 m; Site 8: 39°56′38″N, 116°18′47″N, 61 m; Site 9: 39°55′8″N, 116°18′37″E, 75 m; Site 10: 39°52′13″N, 116°20′53″E, 47 m.

Nomenclature

 *  taiwanensis. Leptanilla taiwanensis Ogata, Terayama & Masuko, 1995: 28, figs. 12-18 (w.q.) TAIWAN.

Worker
HW 0.24-0.25, HL 0.31-0.33, CI 73.1-76.9, SL 0.14-0.15, SI 55.0-63.2, PW 0.14-0.15, WL 0.38-0.40, PNL 0.09-0.10, PNW 0.09, PPNL (postpetiolar node length) 0.08-0.09, PPNW (postpetiolar node width) 0.09-0.10, TL 1.06-1.34 (5 individuals measured).

Head longer than broad, with subparallel sides, slightly concave posterior border and rounded posterior corners. Occipital carina absent. Mandibles narrow, armed with 3 teeth; apical tooth larger and acute; preapical tooth small and low; basal tooth small but distinct, pointed inward and some distance from the preapical tooth. Palp formula 1,1. Clypeus depressed; anterior margin almost straight with low median notch. Antennal insertions exposed, widely separated by low convexity and situated at anterior margin of clypeus with well-marked antennal sclerites. Antennae 12-segmented; scape clavate, extending beyond middle of head, but not reaching posterior margin of head; pedicel separated from the rest of funiculus by constriction; rest of funiculus incrassate, more or less stout, each segment except for apical one broader than long; apical segment longer than broad, about as long as two preceding segments together. Eyes absent.

Trunk slender, with depressed node and subparallel sides. Pronotum with rounded anterior margin and straight posterior margin in dorsal view. Metanotal groove absent. Metapleural gland distinct. Posterior portion of propodeum rounded without distinct posterior declivity; propodeal spiracle small. Legs short and stout; middle tibia with a small simple spur; hind tibia with a small pectinate spur.

Petiole subglobous, longer than broad; petiolar node slightly convex in dorsal view; ventral portion produced with small anterior projection. Postpetiole globous, nearly as long as broad; posterior margin rounded; dorsal surface very convex; ventral portion notably produced.

Gaster rather flattened dorsally; first gastral segment tapering basally, without distinct anterior corners in dorsal view; sting small but distinct.

Queen
HW 0.31, HL 0.34, CI 91.2, SL 0.14, SI 45.2, PW 0.23, WL 0.56, PNL 0.13, PNW 0.21, TL 2.0 (1 individual measured).

Head subrectangular with sides less convex than those of worker; posterior margin concave in the middle; posterior corners rounded; anterior portion not so narrowed as in worker. Mandibles robust, with narrow masticatory margin armed with blunt basal tooth and acute apical tooth. Anterior margin of clypeus broadly rounded without incision. Antennal insertions like those of worker. Antennae 12-segmented; scape stout, pedicel distinguished from the rest of funicular segments by constriction; antennal segments 3-11 each broader than long; apical segment almost as long as two preceding segments together. Eyes and ocelli absent. Two small red spots present on dorsal surface of head through integument, which may be mandibular glands.

Trunk flattened, about 2.5 x as broad as long. Pronotum occupying about two-fifths of whole length of trunk: rounded anteriorly without distinct anterior corners in dorsal view; posterior margin straight. Propleuron large. Metanotal groove absent. Metapleural gland distinct. Ventral processes absent on meso- and metasterna. Propodeal spiracle situated above area between bases of mid and hind coxae. Middle leg with one small and simple tibial spur: hind leg with one small and simple spur and one pectinate spur.

Petiolar node about 1.7x as broad as long, almost same width as trunk with flattened dorsal surface: in dorsal view, anterior margin slightly concave, sides convex, posterior margin almost straight; ventral portion broadly rounded, not forming any projections. Gaster large: first gastral segment l.6x as broad as petiole. Terminal portion without specialized projections.

Body colour pale yellow: hairs short, abundant on gaster.

Type Material
Holotype, worker, Taiwan: Wushe, Nantou Hsien. 14.vii.l982 (M. Terayama) (Type depository: Entomological Laboratory, Faculty of Agriculture. Kyushu University. Type No. 2903). Paratypes. 1queen, 145 workers (same colony as holotype), same nest as holotype (Type depository: Entomological Laboratory, Faculty of Agriculture, Kyushu University: National Institute of Agro-Environmental Sciences. Tsukuba: National Science Museum, Tokyo).