(3 exx.). Holotype: China: ♂, ‘China: Zhejiang, Linan District, West Tianmu Mountain, 1100 m, 23.viii.2014, Cryptomeria leaf, sift, Tie-Xiong Zhao leg., 浙江省临安市西天目山(此路不通)’ (in SNUC). Paratypes: China: 1 ♂ [completely disarticulated specimen], China: Zhejiang, Linan District, West Tianmu Mountain, 1150 m, 2.vii.2006, decomposing log, sift, Xiao-Bin Song leg., 浙江省临安市西天目山(停车场); 1 ♀, ‘China: Zhejiang, Linan District, West Tianmu Mountain, 1180 m, 18.viii.2019, decomposing log, sift, Zi-Wei Yin leg., 浙江省临安市西天目山(消防道)’ (both in SNUC).

Body length 2.8–2.9 mm; dorsal vestiture coarsely punctate and densely setose. Head subrounded at base, with small vertexal and frontal foveae; antennomeres moniliform. Elytra with discal and lateral longitudinal ridges, areas between ridges impressed. Tergite 1 (IV) longer than 2 (V) at middle but clearly shorter than 2 and 3 (VI) combined. Male: antennal clubs formed by apical four enlarged, cylindrical antennomeres. Aedeagus symmetric dorso-ventrally; median lobe C-shaped laterally; parameres thin and elongate, each with two long apical and one preapical seta.

Male. Body (Fig. 1A) length 2.91 mm; color red-brown, tarsi and mouthparts lighter. Dorsal vestiture coarsely punctate and covered with short, dense setae.

Figure 1. 

Habitus of Pseudophanias tianmuensis sp. nov. A male B female. Scale bars: 1.0 mm.

Head (Fig. 2A) subrounded at base, longer than wide, length 0.63 mm, width 0.49 mm; vertex weakly convex, with two small, asetose vertexal foveae (dorsal tentorial pits); antennal tubercles indistinct; frons with single small fovea, protruding anteriorly to form rostrum; clypeus sharply descending, its surface coarse, anterior margin rounded and slightly carinate; lacking ocular-mandibular carina. Venter with two small, well-separated gular foveae (posterior tentorial pits), lacking median carina/sulcus. Maxillary palpus (Fig. 2B) small in size, palpomere 1 minute, 2 pedunculate basally and broadened apically, 3 roundly trapezoidal, 4 broadly at approximately basal 1/3 and gradually narrowing apically. Compound eyes moderately prominent, reniform in lateral view, each composed of approximately 55 ommatidia. Antenna elongate, length 1.75 mm, distinct club (Fig. 2C) formed by greatly enlarged antennomeres 8–11 and approximately as long as antennomeres 1–7 combined (0.88 mm vs 0.87 mm); antennomere 1 large, subcylindrical, 2–7 moniliform, of similar shape, 8, 9 and 10 each much larger than 7, subquadrate, 11 longest, slightly narrower than 10 and as long as 9 and 10 combined.

Figure 2. 

Morphology of Pseudophanias tianmuensis sp. nov., male A head and pronotum B maxillary palpus C antennal club D elytron E meso- and metaventrite F Mesotarsal claws. Scale bars: 0.5 mm (A, D, E); 0.1 mm (B, F); 0.3 mm (C).

Pronotum (Fig. 2A) approximately as long as wide, length 0.66 mm, width 0.63 mm, widest anterior middle; sides from widest point greatly convergent anteriorly and subparallel posteriorly; disc distinctly convex to form hump at middle, lacking carina or sulcus; with small asetose median and lateral antebasal foveae; lacking basolateral foveae. Prosternum with anterior part much shorter than coxal part at middle, with small, asetose lateral procoxal foveae; hypomeron lacking ridge that demarcating it from pronotum; margin of coxal cavity non-carinate.

Elytra much wider than long, length 0.96 mm, width 1.24 mm, truncate at bases; each elytron (Fig. 2D) with two moderately large, asetose basal foveae; with one discal and one lateral ridge, discal stria formed by broad impressed area between ridges; humeral region lacking subhumeral fovea nor marginal stria; epipleural area broad; posterolateral margin with broad notch. Metathoracic wings fully developed.

Mesoventrite (Fig. 2E) with rough surface, with pair of thick admesal carinae, lateral area fully demarcated from metaventrite, openings of median mesoventral foveae widely separated, foveae greatly extended internally, lateral mesoventral foveae unforked, extended internally and overlapped with median foveae; intercoxal process short. Metaventrite (Fig. 2E) coarsely punctate, greatly prominent medially and with small crest; with large, asetose lateral mesocoxal foveae; posterior margin roundly emarginate at middle.

Legs elongate; femora coarsely punctate; each tarsus (Fig. 2F) with one major and one reduced pretarsal claw.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.86 mm, width 1.15 mm. Tergite 1 (IV) slightly less than twice as long as 2 (V), with broad, deep basal sulcus and two basolateral foveae at lateral ends of sulcus, 2 and 3 (VI) successively shorter, lacking basal sulcus nor fovea, 4 (VII), much longer than 3, narrowed posteriorly, with one pair of basolateral foveae; tergites 1–3 each with pair of quadrangular and 4 with pair of triangular paratergites, 5 (VIII) broadly rounded, with one pair of small basolateral foveae, posterior margin roundly emarginate at middle. Sternite 2 (IV) longest, with densely setose basal sulcus and pair of basolateral foveae at lateral ends of sulcus, 3 (V) and 4 (VI) each short at middle, combined approximately as long as 5 (VII), 3–5 lacking sulcus nor fovea at base, 6 (VIII) transverse, posterior margin slightly protruding at middle, 7 (IX) composed of pair of membranous lamellae.

Aedeagus (Fig. 3A–C) 0.51 mm long, dorso-ventrally symmetric; median lobe C-shaped in lateral view and broadened in apical half in dorso-ventral view, with large basal capsule and oval foramen; parameres (Fig. 3D) each thin, elongate and curved ventrally in lateral view, with two apical and one preapical macroseta and four short setae near base.

Figure 3. 

Morphology and habitat of Pseudophanias tianmuensis sp. nov. A–C aedeagus A dorsal B lateral C ventral D paramere, lateral E general environment of the collecting site F decomposing tree branches inhabited by the beetle. Scale bars: 0.2 mm (A–C); 0.1 mm (D).

Female. Similar to male in external morphology (Fig. 1B). Antenna slightly shorter, club less enlarged (0.77 mm for antennomeres 1–7 vs. 0.82 mm for antennomeres 8–11); each compound eye composed of approximately 43 ommatidia; elytra slightly shorter; metathoracic wings also well developed; metaventrite lacking crest at middle. Measurements (as for male): body length 2.84 mm; length/width of head 0.62/0.49 mm, pronotum 0.63/0.65 mm, elytra 0.91/1.22 mm; abdomen 0.83/1.13 mm; length of antenna 1.59 mm.

This species is unique among all known members of the genus in the coarsely punctate body surface, and a rather different type of the male antennal modifications.

The male holotype was collected by sifting Cryptomeria (Cupressaceae) leaves, while the other two individuals were found inside decomposing wood with termites. Although indicated by a set of morphological traits such as the compact body segments and moniliform antennomeres, it is still inconclusive as to whether the beetle has an obligate association with social insects, pending further observations in the field or at the laboratory.

East China: Zhejiang.

The specific epithet refers to West Tianmu Mountain, the type locality of this species.

To accommodate the new species, the key to East and South Asian species of Pseudophanias by Inoue et al. (2020) is modified as follow: