(2 ♂♂, 1 ♀). Holotype: CHINA: ♂, labeled ‘China: S. Zhejiang, Qingyuan, Baishanzu N.R., 27°45'14"N, 119°11'55"E, Fagaceae forest, ant nest in rotten wood, 1650 m, 01.v.2014, X.-B. Song leg. / HOLOTYPE [red], Diartiger zhejiangensis sp. n., det. Yin & Li, 2014, SNUC’. Paratypes: CHINA: 1 ♀, same area and date, except ‘27°45'27"N, 119°12'05"E, mixed leaf litter, sifted, 1700 m, Z. Peng leg.’; 1 ♂ [disarticulated specimen preserved in Euparal on plastic slides], labeled ‘China: S. Zhejiang, Longquan, Fengyang Shan, creek valley nr. hotel, 27°54'42"N, 119°11'52"E, Rhododendron and fir forest, ant nest in erect rotten fir trunk, 1250 m, 28.iv.2014, Peng leg.’. Each paratype bears a type label similar to that of the holotype except ‘PARATYPE [yellow]’.

Male. Body (Fig. 1A) length 2.14–2.15 mm; reddish brown. Head longer than wide, HL 0.39–0.40 mm, HW 0.27–0.28 mm; clypeus with slightly angularly rounded anterior margin; eyes each composed of about 20 facets; antennomeres IV (Fig. 2A) more than twice length of III, with truncate apex. Pronotum about as long as wide, PL 0.37–0.38 mm, PW 0.39–0.41 mm. Elytra (Fig. 2E) wider than long, EL 0.53–0.56 mm, EW 0.80–0.82 mm; lacking microsculpture; with small tuft of setae at posterolateral margins, and bigger triangular, posteriorly-narrowed trichomes at posterior margins. Metathoracic wings fully-developed. Mesoventrite (Fig. 2F) lacking median carina, metaventrite (Fig. 2F) slightly convex, both meso- and metaventrites with row of setae along midline. Profemora (Fig. 2B) with long ventral setae at base, protibiae narrowed at base and thickened from basal third toward apex; mesotrochanters (Fig. 2C) with large, bluntly triangular ventral spine, mesofemora lacking spine; mesotibiae with small apical spur; metatibiae (Fig. 2D) lacking spine or modification. Abdomen slightly wider than long, AL 0.82–0.84 mm, AW 0.88–0.92 mm; composite tergite with transverse basolateral trichomes curved mesally, first pair of paratergites with linear trichomes (Fig. 2G). Aedeagal length 0.50–0.52 mm; median lobe (Fig. 2I–K) with sinuate apical margin in dorso-ventral view.

Female. General form (Fig. 1B) and trichomes on elytra and composite tergite (Fig. 2H) similar to those of male; fourth antennomeres slightly shorter, mesotrochanters and mesotibiae lacking spine; abdomen relatively larger. Each eye composed of about 20 facets. Measurements: BL 2.23 mm, HL 0.41 mm, HW 0.28 mm, PL 0.39 mm, PW 0.43 mm, EL 0.55 mm, EW 0.83 mm, AL 0.88 mm, AW 0.92 mm.

This species is placed as a member of the Diartiger fossulatus group. Males are most similar to those of Diartiger dentatus in possessing relatively short antennomeres III, and in similarities of trichomes on the posterior margins of the elytra and the base of the composite tergite, and in the aedeagal form. The two species can be readily separated by the lack of spines on the mesofemora and middle of the mesotibiae, and lack of a small tubercle on the ventral margin of the metacoxa in Diartiger zhejiangensis, while Diartiger dentatus possesses a sharp basal spine on the ventral margin of the mesofemur, the mesotibia possesses a triangular spine at the middle, and the metacoxa possesses a small tubercle on the ventral margin.

East China: Zhejiang.

The male holotype was collected from a colony of Lasius cf. koreanus (det. Maruyama, pers. comm. 2014) nesting in rotten wood in a predominantly Fagaceae forest (Fig. 3C, D). The female paratype from Baishanzu was collected from a sifted litter sample. The other female paratype collected from Fengyang Shan was found in a small colony of the same Lasius species nesting under bark of a standing rotten fir trunk in a Rhododendron and fir forest (Fig. 3A, B). During a two-day observation period, the adults of Diartiger zhejiangensis (Fig. 3E, F) were totally ignored by the ant workers, and vice versa. This may have been a consequence of the disturbance of being transported and housed in the artificial environment.

The specific epithet refers to the province where the type locality of the new species lies.