Holotype, male (Fig. 20a). Length 2.95 mm. Color of legs, head and ventral surface ferruginous; pronotum and elytron reddish coppery. Body in dorsal aspect with marked constriction between pronotum and elytron; in profile dorsally convex. Rostrum in apical half scabrous, coarsely punctate; in basal half with median and pair of submedian ridges; intervening furrows punctate, each with sparse row of erect setae; epistome with transverse, angulate ridge forming distinct median denticle. Pronotum with sides slightly diverging, anterolaterally rounded to subapical constriction; disk with pair of submedian impressions, coarsely punctate, reticulate; each puncture containing inconspicuous seta; with indistinct median ridge. Elytra with humeri swollen, laterally projecting; interval 5 and 6 behind middle swollen, gently projecting from lateral outline; striae indistinct; intervals flat, punctate; at base and apex densely coarsely punctate; transverse band between humeral and subapical swelling less densely punctate. Anteroventral ridge of femora distinct, in meso- and metafemur forming large tooth. Metafemur subapically with stridulatory patch. Dorsal edge of tibiae subbasally with angulation, in protibia with blunt tooth, in mesotibia with acute tooth, in metatibia denticulate. Abdominal ventrite 5 flat, coarsely punctate. Penis (Fig. 20b) with sides of body subparallel; apex subtruncate, weakly rounded; transfer apparatus compact; apodemes 2.4 × as long as body; ductus ejaculatorius with bulbus. Intraspecific variation. Length 2.43–3.05 mm. Color of pronotum bronze, reddish coppery, or greenish. Female rostrum dorsally with glabrous median costa bordered by rows of punctures and sublateral pair of furrows; epistome simple. Female pronotum ca. 1.1 × as wide as long, male pronotum ca. 1.3 × as wide as long. Female elytra subovate, with lateral contour convex to apex, humeri and intervals 5–6 simple.

Holotype (MZB): ARC1506 (EMBL # LM655604), West Nusa Tenggara Prov., Sumbawa, Batu Dulang, Mt. Batu Pasak, sample 2, S08°37.028', E117°15.783', 1305 m, 12-IV-2010. Paratypes (MZB, SMNK, ZSM): West Nusa Tenggara Prov., Sumbawa: 6 exx, ARC1505 (EMBL # LM655603), ARC1507 (EMBL # LM655605), ARC1508 (EMBL # LM655606), same data as holotype; 6 exx, Batu Dulang, Mt. Batu Pasak, sample 5, S08°37.005', E117°15.790', 1350 m, 18-IV-2010; 1 ex, ARC3589 (PCR failed), Tepal, Pc. Nengas, sample 7, S08°35.176', E117°08.295', 1490 m, 16-IV-2010.

West Nusa Tenggara Prov., Sumbawa (Batu Dulang, Tepal). Elevation: 1305–1350 m.

This epithet is based on the Latin adjective cupreus (copper-colored).

Trigonopterus cupreus Riedel, sp. n. was coded as “Trigonopterus sp. 332”.