Holotype, male (Fig. 98a). Length 3.76 mm. Color of legs and antennae ferruginous, remainder black. Body elongate; in dorsal aspect with marked constriction between pronotum and elytron; in profile dorsally evenly convex. Rostrum with median carina terminating on forehead and pair of submedian ridges; intervening furrows each with row of erect piliform scales; epistome with transverse, angulate ridge forming indistinct median denticle. Pronotum anterolaterally markedly projecting, rounded; with subapical constriction; disk coarsely punctate, partly scabrous, interspaces microreticulate; each puncture containing small seta; disk with pair of submedian, shallow impressions. Elytra with striae indistinct; intervals flat; punctation dense, confused, near basal margin punctures partly confluent; each puncture containing small recumbent seta; interspaces dull, coriaceous, microreticulate; interval 7 swollen subapically, laterally weakly projecting; sutural interval at apex forming median, apically bifid protrusion. Anteroventral ridge of femora forming blunt tooth. Metafemur subapically with stridulatory patch and transverse row of denticles. Abdominal ventrite 5 flat, coarsely punctate, sparsely setose with long erect setae. Penis (Fig. 98b) with body in profile markedly curved ventrad; sides of body subparallel; apex broadly rounded; transfer apparatus minute; apodemes slightly shorter than body; ductus ejaculatorius without bulbus. Intraspecific variation. Length 2.68–3.88 mm. Integument of males dull, microreticulate; females with punctures sparser and smaller, interspaces polished. Female rostrum dorsally with glabrous median costa and pair of submedian costae separated by punctate furrow; epistome simple. Female elytra with lateral contour from humeri more evenly convex to apex; suture extended into acute process. Penis with body relatively short and robust in Western population; rather slender, long, basally markedly curved in Central population; intermediate between these two in Eastern population.

Holotype (MZB): ARC2514 (EMBL # LM655851), West Java Prov., Bandung, Lembang, Pangli, Mt. Bukittinggul, sample 1, S06°48.810', E107°44.216', 1753 m, 03-XII-2011. Paratypes (MZB, SMNK, ZSM): 2 exx, ARC0254 (EMBL # LM655446), ARC0255 (EMBL # LM655447), W-Java Prov., Telaga Warna, between Puncak and Cipanas, S06°42.253', E106°59.755', sample 1, 1584 m, 06-VIII-2006; 1 ex, ARC2662 (EMBL # LM655920), W-Java Prov., Sukabumi, Mt. Gede, Cisaat, Situ Gunung, sample 3, S06°48.628', E106°56.077', 1462 m, 16-IV-2012; 1 ex, ARC2667 (EMBL # LM655925), W-Java Prov., Sukabumi, Mt. Gede, Cisaat, Situ Gunung, sample 7, under Lithocarpus sp., S06°48.377', E106°56.183', 1637 m, 16-IV-2012; 3 exx, ARC2515 (EMBL # LM655852), same data as holotype; 4 exx, ARC2518 (EMBL # LM655855), ARC2519 (EMBL # LM655856), W-Java Prov., Bandung, Lembang, Pangli, Mt. Bukittinggul, sample 2, S06°48.845', E107°44.074', 1898 m, 03-XII-2011; 7 exx, ARC2706 (EMBL # LM655962), ARC2707 (EMBL # LM655963), ARC2708 (EMBL # LM655964), W-Java Prov., Garut, Cikajang, Mt. Payung, sample 2, S07°25.268', E107°48.492', 1250 m, 26-IV-2012; 6 exx, ARC2712 (EMBL # LM655968), W-Java Prov., Garut, Cikajang, Mt. Payung, sample 3, S07°25.320', E107°48.259', 1560 m, 26-IV-2012; 3 exx, ARC0205 (EMBL # LM655427), ARC0206 (EMBL # LM655428), ARC0207 (EMBL # LM655429), W-Java Prov., Garut, Cilawu, Mt. Cikuray, sample 1, S07°18.578', E107°52.622', 1648 m, 24-IX-2005; 3 exx, ARC0161, ARC0187 (EMBL # LM655412), W-Java Prov., Garut, Cilawu, Mt. Cikuray, sample 2, S07°18.840', E107°52.512', 1800 m, 24-IX-2005; 7 exx, ARC2720 (EMBL # LM655976), ARC2721 (EMBL # LM655977), ARC2722 (EMBL # LM655978), W-Java Prov., Garut, Wanaraja, Talagabodas, sample 2, S07°11.966', E108°03.984', 1719 m, 27-IV-2012; 1 ex, ARC2723 (EMBL # LM655979), W-Java Prov., Garut, Wanaraja, Talagabodas, sample 1, S07°12.511', E108°03.554', 1741 m, 27-IV-2012; 6 exx, ARC0162, ARC0173, ARC0199 (EMBL # LM655421), ARC0200 (EMBL # LM655422), W-Java Prov., Ciamis, Mt. Sawal, Batu Cakra, S07°14.920', E108°15.762', 990 m, 01-X-2005; 1 ex, W-Java Prov., Ciamis, Mt. Sawal, Blok Cireong, sample 2, S07°14.127', E108°15.568', 1120 m, 01-X-2005; 9 exx, ARC0293 (EMBL # LM655483), ARC0294 (EMBL # LM655484), ARC0295 (EMBL # LM655485), C-Java Prov., N slopes of Dieng figau, Petungkriyono, mountain N Tinalum, sample 1, S07°06.418', E109°44.514', 1115 m, 22-VIII-2006; 6 exx, ARC0298 (EMBL # LM655488), ARC0299 (EMBL # LM655489), ARC0300 (EMBL # LM655490), C-Java Prov., N slopes of Dieng figau, Petungkriyono, Mt. Deles, sample 3, S07°08.225', E109°43.555', 1495 m, 24-VIII-2006; 7 exx, C-Java Prov., N slopes of Dieng figau, Petungkriyono, Mt. Deles, sample 1, S07°08.221', E109°43.599', 1505 m, 24-VIII-2006; 2 exx, C-Java, Mt. Slamet, Guci, sample 5, S07°11.953', E109°10.497', 1620 m, 27-XI-2011; 6 exx, ARC2499 (EMBL # LM655836), ARC2500 (EMBL # LM655837), Central Java Prov., Mt. Slamet, Guci, sample 6, S07°11.983', E109°10.556', 1671 m, 27-XI-2011; 9 exx, ARC2501 (EMBL # LM655838), ARC2502 (EMBL # LM655839), C-Java Prov., Mt. Slamet, Guci, sample 4, S07°12.304', E109°10.450', 1406 m, 27-XI-2011.

W-Java Prov. (Mt. Gede N.P., Mt. Bukittinggul, Mt. Cikuray, Mt. Payung, Talagabodas, Mt. Sawal), C-Java Prov. (Dieng, Mt. Slamet). Elevation: 990–1898 m.

This epithet is based on the Latin adjective vulcanicus and refers to its presence on volcanic mountains.

Trigonopterus vulcanicus Riedel, sp. n. was coded as “Trigonopterus sp. 313”. This species is divided into three populations that exhibit slightly different shapes of the penis; however, they hardly justify recognition as separate species. The western population is found at Mt. Gede; the central population at Mt. Bukittinggul, Mt. Cikuray, Mt. Payung and Talagabodas; and the Eastern population at Mt. Sawal, Dieng, and Mt. Slamet.