Holotype, male (Fig. 89a). Length 2.53 mm. Color of head, legs, and sutural interval of elytra ferruginous, remainder black. Body in dorsal aspect with marked constriction between pronotum and elytron; with distinct constriction in profile. Rostrum with median ridge and pair of submedian ridges, intervening furrows punctate; epistome with indistinct, transverse, subangulate ridge. Pronotum anterolaterally angularly projecting; with distinct subapical constriction; disk punctate, interspaces microreticulate; punctures each with one slender suberect scale; with median ridge. Elytra with striae deeply impressed, each with row of slender, suberect scales; intervals carinate, almost nude, microreticulate; sutural interval basally swollen; interval 7 swollen subapically, laterally weakly projecting. Femora edentate. Metafemur subapically with stridulatory patch and transverse ridge. Abdominal ventrite 5 flat, densely punctate, sparsely setose. Penis (Fig. 89b) with body flattened, in profile markedly curved; in dorsal aspect sides subparallel; apex with median, triangular extension; transfer apparatus flagelliform, slightly longer than body; apodemes 2.4 × as long as body; ductus ejaculatorius without bulbus. Intraspecific variation. Length 2.10–2.58 mm. Color of body with sutural interval ferruginous or completely black. Body shape slightly more elongate or compact. Female rostrum dorsally with pairs of lateral and submedian furrows; epistome simple.

Holotype (MZB): ARC2652 (EMBL # LM655910), West Java Prov., Bogor, Cidahu, Mt. Salak (near Javana Spa), sample 3, S06°43.425', E106°43.227', 1756 m, 13-IV-2012. Paratypes (ARC, MZB, SMNK, ZSM): W-Java Prov.: 6 exx, ARC0104, ARC0184 (EMBL # LM655409), Mt. Halimun N.P., Pasir Banteng, Mt. Botol, 1550 m, 17-XI-2004; 3 exx, Mt. Halimun N.P., Citalahab, Mt. Kendeng, 1550 m, 19-XI-2004; 3 exx, ARC2648 (EMBL # LM655906), ARC2649 (EMBL # LM655907), Bogor, Cidahu, Mt. Salak (near Javana Spa), sample 1, S06°43.733', E106°42.711', 1429 m, 13-IV-2012; 5 exx, same data as holotype; 1 ex, ARC2653 (EMBL # LM655911), Sukabumi, Mt. Gede, Cisaat, Situ Gunung, sample 1, S06°49.377', E106°55.729', 1281 m, 15-IV-2012; 1 ex, ARC2663 (EMBL # LM655921), Sukabumi, Mt. Gede, Cisaat, Situ Gunung, sample 5, S06°47.912', E106°56.457', 1940 m, 16-IV-2012; 1 ex, Sukabumi, Mt. Gede, Cisaat, Situ Gunung, sample 4, S06°48.250', E106°56.271', 1720 m, 16-IV-2012; 4 exx, ARC2666 (EMBL # LM655924), Sukabumi, Mt. Gede, Cisaat, Situ Gunung, sample 7, S06°48.377', E106°56.183', 1637 m, 16-IV-2012, under Lithocarpus sp.; 1 exx, ARC0159, Garut, Kawah Kamojang, sample 2, S07°09.578', E107°47.802', 1400 m, 26-IX-2005; 2 exx, ARC0182 (EMBL # LM655407), Garut, Kawah Kamojang, sample 3, S07°09.497', E107°47.828', 1430 m, 26-IX-2005; 4 exx, ARC0256 (EMBL # LM655448), ARC0257 (EMBL # LM655449), ARC0258 (EMBL # LM655450), Telaga Warna, between Puncak and Cipanas, sample 1, S06°42.253', E106°59.755', 1585 m, 06-VIII-2006; 11 exx Telaga Warna, between Puncak and Cipanas, sample 2, S06°42.097', E106°59.833', 1477 m, 06-VIII-2006.

W-Java Prov., (Mt. Gede, Mt. Halimun N.P., Kawah Kamojang, Mt. Salak). Elevation: 1400–1940 m.

This epithet is based on the Latin adjective suturalis and refers to the basally swollen elytral suture.

Trigonopterus suturalis Riedel, sp. n. was coded as “Trigonopterus sp. 304”.