(24 ♂♂, 28 ♀♀). Holotype: ♂, labeled ‘25°53'03.51"N, 110°29'15.67"E / Maoer shan / (1, 150 m). Xingan County / Guilin City / [Guangxi, China] / 24.VII.2012, Song X-B & Hu J-Y // HOLOTYPE [red] / Pella maoershanensis sp. n. / Song & Li / det. 2013, SNUC’. Paratypes: 23 ♂♂, 28 ♀♀, same label data as holotype, all bearing the following label: ‘PARATYPE [yellow] / Pella maoershanensis sp. n. / Song & Li / det. 2013, SNUC’.

Pella maoershanensis shares with Pella puetzi a similar form of male sexual character on the head (Assing 2009). The two species can be readily distinguished by the smaller body size, the distinctly transverse antennomeres VI–X, and different forms of the aedeagal distal crest and ventral process in Pella maoershanensis. The new species is also similar to the other species of the Pella cognata group in general appearance (Maruyama 2006) but can be readily separated by the sexually modified head in the male.

Body (Fig. 1A) length: 5.5–5.8 mm. Coloration: fore body brownish; abdomen blackish, with the posterior margins of the segments reddish-brown; leg and antennae reddish-brown.

Head (Fig. 1A) almost 1.2 times as wide as long; widest just behind eyes; surface finely reticulate, covered with short golden setae. Antennae (Fig. 1D) about 2.2 mm long, shorter than head, pronotum and elytra combined; antennomeres VI–X distinctly transverse. Pronotum (Fig. 1E) 1.35 times as wide as long and 1.37 times as wide as head; widest around anterior third, narrowed posteriorly; posterior margin almost rounded; covered with short golden setae, with six macrosetae; hypomera fully visible in lateral view. Elytra (Fig. 1A) about 1.9 times as long as pronotum; covered with short golden setae; humeral angle with one macrosetae. Hind wings fully developed. Abdomen (Fig. 1A) widest at segments IV–V; surface with transverse microsculpture.

Male. Posterior margin of head distinctly angled at middle (Fig. 1B); posterior margin of tergite VIII broadly concave and finely crenulate (Fig. 1F); posterior margin of sternite VIII (Fig. 1H) almost truncate; median lobe of aedeagus as in Figs 1J–L.

Female. Posterior margin of head indistinctly angled at middle (Fig. 1C); tergite VIII (Fig. 1G) and sternite VIII (Fig. 1I) distinctly shorter than that of male; spermatheca as in Fig. 1M.

Lasius (Dendrolasius) spathepus (det. by M. Maruyama) (Figs 2A, B).

Species of Pella are usually observed walking around the host’s nest but never appear in it (Maruyama 2006). All individuals of the new species, plus three other aleocharine species were taken by sifting mixed leaf litter around the ant nest (Fig. 2C). Three possible larvae of the new species were taken back to the lab, and were observed to feed on a dead worker of the host ant (Fig. 2D). It’s worth a note that two males and a female of an undescribed Dendrolasiophilus Nomura species (Yin pers. comm.) were directly collected from the deep site of the nest.

Named after the type locality.