Pengzhongiella daicongchaoi sp. n. (here designated).

Head rectangular; lacking frontal rostrum. Pronotum with distinct lateral longitudinal sulci, disc barely convex; lateral antebasal foveae present; lacking median antebasal fovea, antebasal sulcus, antebasal tubercles, and basolateral foveae. Each elytron with three reduced basal foveae, lacking discal stria. Abdomen with basolateral foveae on tergites IV–VII; tergite IV the longest.

Length 2.02–2.18 mm. Head (Fig. 2A) rectangular; lacking frontal rostrum and frontal fovea, antennal tubercles indistinct; punctiform vertexal foveae nude, shallow U-shaped impression connecting foveae; with 11 antennomeres, clubs formed by apical three antennomeres (Figs 3A, B); lacking ocular-mandibular carinae; eyes rounded, with posteroventral margins shallowly emarginate; maxillary palpi with palpomeres II basally pedunculate, III nearly triangular, IV fusiform; gular foveae (Fig. 2B) in shared opening, linear gular carina slightly indicated.

Pronotum (Fig. 2C) with distinct lateral longitudinal sulci, lacking median longitudinal and antebasal sulci; small lateral antebasal foveae nude, lacking median antebasal fovea and antebasal spines; basolateral foveae absent, replaced by shallow impressions; lateral margins lacking spines. Prothorax (Fig. 2D) lacking paranotal sulci; with lateral procoxal foveae.

Each elytron with three punctiform basal foveae (Figs 3C, D), lacking discal stria; lacking subbasal foveae; sutural stria complete; subhumeral fovea present, with complete marginal stria (Fig. 3E); apicolateral margins broadly emarginate.

Mesoventrite (Fig. 3F) with lateral foveae forked for short distance, anterior fork as wide as median fork, median fovea widely separated, opening into shared transverse cavity; lateral mesocoxal foveae small; small lateral metaventral foveae close; metacoxae moderately separated; metaventrite with median sulcus extending to near apex, apex with narrow slit.

Tergite IV (first visible tergite) longest (Fig. 3I), deeply impressed across base, basolateral foveae in lateral endings of sulcus; lacking marginal carinae; V–VII subequal in length, lacking mediobasal sulcus, with basolateral foveae. Sternite IV (second visible sternite) longest (Fig. 3J), with mediobasal foveae at inner margins of shallow basolateral sulci, two pairs of small basolateral foveae present; sternite IV about twice length of V at midline, V–VII successively shorter, with pair of basolateral foveae.

First two pairs of tarsi with second and third tarsomeres subequal in length, metatarsi with second tarsomeres longer than third ones.

Males with antennae, mesotibiae, and metatrochanters modified. Aedeagus with dorsal lobe largely fused to median lobe, paramere connected with median lobe by membrane.

At this time Pengzhongiella cannot be placed near any genus, and seems to form an isolated group within Batrisina. The long appendages are rarely observed in Asian myrmecophilous batrisines. Coupled with the foveal pattern of the head, pronotum, and elytra, and other external characters, Pengzhongiella can be quickly separated from all known genera, especially the myrmecophilous members of the Asian Batrisitae. The exceptionally elongate antennae and legs are shared with the Sumatran Akarbatrus Löbl and the Australian Mossman Chandler. Both Akarbatrus and Mossman lack elytral basal foveaeand the basal impression of the tergite IV. The former has a sexually modified pronotum in the male, while Mossman has the pronotum lacking lateral longitudinal sulci, with two antebasal tubercles, and an outer pair of basolateral foveae (Chandler 2001, Löbl 2009). Pengzhongiella has three punctiform foveae at the base of each elytron, the pronotum has a pair of lateral sulci and small antebasal foveae, while other sulci and foveae are completely reduced probably due to the myrmecophily, and tergite IV has a thin, deep basal sulcus.

The new genus and species is named in honor of Zhong Peng and Cong-Chao Dai, respectively, for their collection of the type series. Gender of the generic name is feminine.

(6 ♂♂, 35 ♀♀). Holotype: CHINA: ♂, labeled ‘China: W. Yunnan, Baoshan, S. Gaoligong Mt., Baihualing, ca. 42 km NE Tengchong, 25°117'36"N, 98°47'51"E, broad-leaved forest, nest of Odontomachus monticola, 1550–1600 m, 20.iv.2013, Peng & Dai leg. / Holotype [red], Pengzhongiella daicongchaoi sp. n., det. Yin & Li, 2013, SNUC’. Paratypes: CHINA: 5 ♂♂, 35 ♀♀, same label data as holotype, and all bear a paratype label as ‘Paratype [yellow], Pengzhongiella daicongchaoi sp. n., det. Yin & Li, 2013, SNUC’.

Male (Fig. 1A). BL 2.02–2.07 mm. Body reddish brown, maxillary palpi, tibiae, and tarsi lighter in color. Head, pronotum and elytra covered with fine setae. Head (Fig. 2A) as long as wide, HL 0.40–0.42 mm, HW 0.42–0.44 mm; vertex flat, vertexal foveae at level of posterior margins of eyes, connected by weakly indicated U-shaped impression; eyes moderately developed, each composed of about 40 facets; antennae greatly elongate, antennomeres X–XI (Fig. 3A) modified, XI longest, markedly concave basally. Pronotum (Fig. 2C) as long as wide, PL 0.46–0.47 mm, PW 0.47–0.48 mm; shallowly punctate; with rounded lateral margins; narrowed at base. Elytra (Fig. 3C) slightly wider than long, EL 0.66–0.67 mm, EW 0.71–0.72 mm; with rounded lateral margins. Metathoracic wings fully developed. Protibiae thickened (Fig. 1A); mesotibiae (Fig. 3G) bear tiny preapical tubercle; metatrochanters (Fig. 3H) greatly projecting at ventral margins. Abdomen wider than long, AL 0.50–0.51 mm, AW 0.64–0.65 mm, rounded at posterior margin. Aedeagus (Figs 3K–M) asymmetric, length 0.32 mm; basal bulb with large foramen; median lobe flattened dorso-ventrally; paramere weakly sclerotized.

Female (Fig. 1B). Similar to male in general. Measurements: BL 2.13–2.18 mm, HL 0.43–0.44 mm, PL 0.50–0.51 mm, PW 0.50–0.51 mm, EL 0.69–0.71 mm, EW 0.76–0.79 mm, AL 0.51–0.52 mm, AW 0.69–0.74 mm. Each eye composed of about 32 facets. Antennae simple. Metathoracic wings fully developed. Legs with protibiae narrower than those in male; mesotibiae lacking tubercle; metatrochanters simple. Width of genital complex 0.22 mm, slightly sclerotized, transverse.

The characteristic antennae and aedeagus, combined with the generic characters (see ‘Comparative notes’ of the genus), provide a quick separation of the new species from all other members of the Batrisini.

Southwest China: Yunnan.

All individuals of Pengzhongiella daicongchaoi were collected from a colony of Odontomachus monticola nested inside a rotten fallen tree, at the side of a road in an evergreen broad-leaved forest (Fig. 4A–D).It’s worthy of a note that a highly specialized species (lacking vertexal and pronotal median antebasal foveae) of Batraxis Reitter (22 ex.), one species of Batrisoschema Reitter (18 ex.), and one species of Harmophorus Motschulsky (5 ex.) were found in the same nest. Previously, no pselaphine has ever been reported living with members of the ant genus Odontomachus.