Holotype, male (Fig. 10a). Length 2.60 mm. Color of legs and head ferruginous, remainder black. Body elongate; in dorsal aspect with marked constriction between pronotum and elytron; with distinct constriction in profile. Rostrum coarsely rugose-punctate, with median ridge and pair of irregular submedian ridges; epistome with indistinct, transverse, subangulate ridge. Pronotum with distinct subapical constriction; disk scabrous, punctures each with one erect seta; with median ridge. Elytra with striae deeply impressed, each with row of stout suberect bristles; intervals tuberculate, almost nude; sutural interval apically extended; interval 7 swollen subapically, laterally weakly projecting. Femora edentate. Metafemur subapically with stridulatory patch. Abdominal ventrite 5 flat, densely punctate, setose. Penis (Fig. 10b) with body flattened, in profile markedly curved; in dorsal aspect sides subparallel; apex with median, subtriangular extension; transfer apparatus flagelliform, 1.5 × longer than body; apodemes 2.6 × as long as body; ductus ejaculatorius without bulbus. Intraspecific variation. Length 2.48–2.60 mm. Female rostrum dorsally with pairs of lateral and submedian furrows; epistome simple.

Holotype (MZB): ARC2520 (EMBL # LM655857), West Java Prov., Bandung, Lembang, Pangli, Mt. Bukittinggul, sample 3, S06°48.807', E107°43.897', 1983 m, 03-XII-2011. Paratypes (MZB, SMNK, ZSM): Bandung, Lembang, Pangli, Mt. Bukittinggul: 10 exx, ARC2521 (EMBL # LM655858), ARC3639 (EMBL # LM656061), same data as holotype; 4 exx, sample 2, S06°48.845', E107°44.074', 1898 m, 03-XII-2011; 10 exx, ARC2522 (EMBL # LM655859), sample 4, S06°48.660', E107°43.722', 2185 m, 03-XII-2011.

W-Java Prov. (Mt. Bukittinggul). Elevation: 1983–2185 m.

This epithet is based on the Latin adjective asper (rough, coarse) and refers to its body sculpture.

Trigonopterus asper Riedel, sp. n. was coded as “Trigonopterus sp. 359”. It is closely related to Trigonopterus variolosus Riedel, sp. n. from which it can be separated by a larger penis with a longer flagellum. The minimal p-distance between both species is 9.5%.