Hexarhopalus (Hexarhopalus) ruzzieri, Purchart, 2025

Hexarhopalus (Hexarhopalus) ruzzieri sp. nov.

( Figs 2a–l View FIGURE 2 )

Type material. Holotype ♂ ( NMPC): {white, printed} VIETNAM, Qu ảng Bình prov. / Lệ Th ủy distr., iv.2023 / Kim Th ủy env., 700 m / local collector leg . Paratypes. (1 ♀ NMPC, 1 ♂ BMNH, 1 ♂ ERPC, 2 ♂ + 4 LPCB): same data as holotype; (3 ♂ + 2 ♀ + 1 LPCB): {white, printed} VIETNAM, Yên Bái prov. / Yên Bái env., ix.2020 / local collector leg.; (4 ♂ + 4 ♀ LPCB, 1 ♀ NHMB): {white, printed} VIETNAM, Yên Bái prov. / Mù Cang Ch ải env. / ix.2023, 1600 m / local collector leg .

Differential diagnosis. Owing to its black body colour and presence of large and well separated tubercles in elytral interstriae, it can only be confused with H. tuberculatus (Pic, 1928) ( Figs 4f, g View FIGURE 4 ), H. tuberculipennis Kaszab, 1960 (see Fig. 14 in Kaszab 1960) and H. loebli Bečvář & Purchart, 2007 (see Fig. 4 View FIGURE 4 in Bečvář & Purchart 2008). Hexarhopalus ruzzieri sp. nov., however, differs at first glance from H. tuberculipennis and H. loebli by its distinct and shiny rugosity, which covers the entire pronotal surface ( Figs 2a, d View FIGURE 2 ), whereas it is completely smooth in H. loebli ( Figs 6e, m View FIGURE 6 ) or with several tubercles and three shallow depressions in H. tuberculipennis ( Figs 6h, p View FIGURE 6 ). Hexarhopalus tuberculatus differs from the new species by the pronotal surface covered by large shiny granules, by large, deep and broad midlongitudinal groove on pronotal disc and by deep well developed oblique indentations in posterior angles of the pronotum (see Fig. 1A View FIGURE 1 in Bečvář & Purchart 2008), whereas in the new species, the pronotal surface is covered by irregular rugosities, pronotal disc with shallow midlongitudinal impression and oblique shallow indentations ( Figs 2d, e View FIGURE 2 ). The new species also resembles H. kaminskii sp. nov., H. higurashii Masumoto & Akita, 2022 and H. julioi Jang & Chen, 2024 but differs from them by isolated tubercles in elytral interstriae becoming confluent in the latter three species.

Description. Size of holotype 14.6 × 6.3 mm. Body black, elongate oval, strongly convex ( Figs 2a–c View FIGURE 2 ).

Head narrower than pronotum in ratio 1:1.46 ( Figs 2a, d View FIGURE 2 ). Whole surface densely and coarsely punctate, in places with several shiny rugosities. Frontoclypeal suture weakly marked, complete, broadly U-shaped. Ocular sulcus moderately deep. Distance between eyes 2× wider than their transverse diameter (DV). Labrum brown, shiny, transverse, flat, apically with long yellow setae. Antenna dark brown, shiny, 1.23× longer than pronotum, covered with yellow adherent hairs. Palpomeres shiny, apical maxillary palpomere securiform. Mentum with well visible lateral wings, middle part of mentum with two shallow longitudinal grooves.

Pronotum slightly but evenly convex (LV), coarsely sculptured, nearly as long as broad, widest at middle, sides rounded in anterior three fourth, depressed posterolaterally in the posterior fourth, straight in basal fourth ( Figs 2a, d View FIGURE 2 ). PW:PL ratio is 1:1.05. Pronotal margins completely bordered, except for anterior margin which is completely unbordered. The latter concave (in DV), anterior angles obtuse. Basal pronotal margin rounded in middle. Oblique indentation in posterior angles shallow but well obvious ( Fig. 2e View FIGURE 2 ). Dorsal surface densely covered with shiny rugosities, space between them shagreened, thus strongly matt. Dorsum with shallow midlongitudinal impression. Prothoracic hypomeron shagreened, glabrous, mostly smooth but transversally wrinkled along posterior pronotal border.

Elytra ovate, evenly convex with slightly flattened disc (LV), 1.4× longer than its width and 2.26× longer and 1.54× wider than pronotum, broadest at midlength (DV), highest at midlength (LV). Basal margin not bordered or carinated. Whole elytral surface shagreened with exception of large and small tubercles situated in flat elytral interstriae. Striae indicated by small punctures of same size as eye facet arranged regularly in rows. Large tubercles in elytral interstriae arranged more or less regularly in rows, small tubercles (approx. as large as eye facet) arranged irregularly ( Figs 1a, c View FIGURE 1 ). Scutellum broadly triangular ( Fig. 1d View FIGURE 1 ). Apterous.

Prosternum shagreened, matt, longitudinally wrinkled. Prosternal process steeply inclined anteriorly, with distinct grove between coxae, almost vertically declivous behind coxae, apical part horizontal, flat, apex rounded. Mesoventrite coarse in apical half, shagreened, with shiny midlongitudinal carina in middle, posterior part steeply inclined towards mesocoxae, shegreend, matt. Metaventrite narrow (narrower than mesocoxa), shagreened, matt, sparsely and shallowly punctate. Abdominal ventrites glabrous, covered densely with very shallow punctures, shagreened, matt ( Fig. 2b View FIGURE 2 ).

Legs shiny, densely punctate; protibiae curved in both sexes.

Aedeagus, spiculum gastrale, male inner sternite VIII, male inner tergite VII and VIII see Figs 2f–l View FIGURE 2 .

Variability of size: 13.6–15.7 × 5.9–6.5 mm.

Etymology. Named in honour of my colleague and friend Enrico Ruzzier ( Italy), a prominent expert on Tenebrionidae and Mordellidae .