(8 specimens). Holotype: CHINA: ♂: ‘Taiwan, Taitung County (台东县), Haiduan Township (海端乡), Lidao (利稻), 23°10'55"N, 120°57'53"E, 1150 m, 24.iii.2017, light trap, Chou Wen-I leg.’ (in SNUC). Paratype: CHINA: 7 ♂♂, same collecting data as the holotype (5 in SNUC, 2 in NMNS).

Body length slightly more than 2 mm; metaventrite with pair of laminar projections; abdominal tergite 1(IV) with large cavity at posterior half, lateral setiferous patches composed of short setae and weakly demarcated; legs lacking modifications, except mesotibia with distinct apical spur; aedeagus with median lobe strongly curved rightwards apically, dorsal lobe erect, and strongly narrowed and curved downwards at apex.

Male (Fig. 1A). Length 2.09–2.22 mm; body reddish-brown, maxillary palpi and tarsi lighter. Head and pronotum (Fig. 1B) sparsely punctate. Head slightly wider than long, length from anterior margin of clypeus to head base 0.40–0.42 mm, width across compound eyes 0.44–0.47 mm; each eye composed of about 30 facets. Antennal clubs loosely formed by apical three antennomeres. Pronotum about as long as wide, length along midline 0.46–0.48 mm, maximum width 0.44–0.48 mm; lateral margins rounded at middle, constricted and nearly parallel at basal 1/3. Elytra wider than long, length along suture 0.66–0.72 mm, maximum width 0.77–0.83 mm; shallow discal striae reaching past 3/4 of elytral length; marginal sulcus complete; with slight denticle at humeral angle. Metaventrite with one pair of laminar projections (Fig. 1C) at middle. Mesotrochanter slightly protuberant at ventral margin; mesotibia with distinct apical spur (Fig. 1D). Abdomen slightly narrower than elytra, length of dorsally visible part posterior to elytra along midline 0.57–0.60 mm, maximum width 0.65–0.68 mm; tergite 1(IV) (Fig. 1E) much longer than 2–4 (V–VII) combined, deeply and broadly concaved at posteromedian portion, anterior margin of cavity angularly protruding posteriorly, with two pairs of secretory setae, elongate setae along lateral margins pointed posteromedially, bottom of cavity glabrous, with two pairs of secretory setae at middle and at sides, with one large nodule located posterior of cavity, setiferous lateral patches composed of short setae and weakly demarcated. Aedeagus (Fig. 1F–G) asymmetric, length 0.37 mm; median lobe strongly curved rightwards apically, capsule with distinct basoventral projection; parameres fused and reduced to ventral membrane; dorsal lobe erect, strongly narrowed and curved downwards at apex.

Figure 1. 

Arthromelodes choui sp. n., male. A habitus B head and pronotum C metaventrite, showing laminar projections at the middle D apex of mesotibia E tergite 1(IV), showing abdominal modification F–G Aedeagus, in lateral (F), and ventral (G) view. Scale bars: 0.5 mm (A); 0.2 mm (B, E); 0.1 mm (C, F–G); 0.05 mm (D).

Female. Unknown.

Using the key in Nomura (1991), Arthromelodes choui would key out at couplet 9 with A. sinuatipes Nomura and A. aizuanus Nomura. These three species share the presence of a cavity on male tergite 1(IV), a nodule placed posterior to the cavity, as well as a pair of setiferous patches lateral to the cavity. Arthromelodes choui may be readily separated from A. sinuatipes by the less laterally expanded margins of tergite 1, the less demarcated setiferous patches, the sinuate anterior margin of tergal cavity, and the much less transverse basal capsule of the aedeagus; and from A. aizuanus by the much larger abdominal cavity, the broader and less demarcated setiferous patches, and much shorter basoventral projection of the aedeagus. A similar tergal cavity and nodule are also present in A. dilatatus (Raffray) (with four subspecies), but this species can be easily characterized by the distinct lateral expansions at sides of tergite 1(IV), while the new species lacks such structures. Arai (2002) described A. watanabei Arai from Honshu, Japan, and this species may be separated from A. choui by the cavity on tergite 1 being much smaller and shallower, and by the form of the aedeagus (Arai, 2002: figs 1, 6–7). According to the description and figures in Jeannel (1954: 249), A. choui may be well-separated from A. carieri Jeannel (type species of Arthromelodes) from Vietnam again by the different structures of the male tergal cavity and aedeagus.

Southern China: Taiwan.

The specific epithet is dedicated to my friend Wen-I Chou, a Taiwanese specialist of Cerambycidae, who collected the type series of the new species.