Cercyon (s. str.) vividus d'Orchymont, 1925: 279 Cercyon ( Clinocercyon ) vividus Orchymont Taxonomic Revision and Phylogeny of the Genus Peltocercyon d'Orchymont, 1925 (Coleoptera: Hydrophilidae: Megasternini) Mai, Zuqi Jia, Fenglong Ryndevich, Sergey K. Angus, Robert Minoshima, Yûsuke N. Fikáček, Martin Růžička, Jan Zootaxa 2025 2025-08-01 5671 1 1 74 (d'Orchymont, 1925) Mai & Jia & Ryndevich & Angus & Minoshima & Fikáček & Růžička 2025 d'Orchymont 1925 [151,670,798,825] Insecta Hydrophilidae Peltocercyon Animalia Coleoptera 36 37 Arthropoda species vividus comb. nov.   Figs 19A–G, 20A–D, 33D–F      Cercyon(s. str.)  vividus d'Orchymont, 1925: 279. Typelocality: Hoa Binh, Tonkin.   Cercyon( Clinocercyon) vividusOrchymont; Orchymont, 1942: 2.   Type material examined.   Holotype( Fig. 33D–F): male ( IRSNB), “ Hoa Binh/ Tonkin/ de Cooman // TYPE // Cercyon(s. str.) / vividus / Type // Coll. R. I. Sc. N. B”.  Paratype: 1 male( IRSNB), “ Hoa Binh/ Tonkin/ de Cooman // Para-/ type”  Additional material:   MALAYSIA: 6 spec.( NMP), “W MALAYSIA: Selangor/ Ulu Gombakfield studies centre (  22 kmNE Kuala Lumpur) / 3°19’32’’N, 101°45’16’’E/ lgt. Damir Kovac, 2007 // BS3107 /  21.VIII.2007/ felled young bamboo shoot (  Gigantochloa scortechinii) laying on the ground”.   THAILAND: 5 spec.( NMP), “THAILAND: Mae Hong Son Pang Mapha dist.,  5 kmSE of Soppong[= Pang Mapha] / Ban Pha Monenv., Damir Kovaclgt. 2006 // B195/06 /  1.VIII.2006/ felled young bamboo shoot (  Dendrocalamus giganteus)”.   LAOS: 4 males, 1 female( NHMB), “LAOS-N ( Louangphra-bang),  11–21.Ⅴ.2002, 19°35’N 101°58’E, THONG KHAN,  750 m, Vit KubÁňleg. // Collection Naturhistorisches Museum Basel”;   INDONESIA: 1 female( NMEG). “INDONESIA N-Sulawesi / vlc. Boyong Atas, ca.  550 m/ 1°05’50’’N, 124°25’26’’E/  21.II.2009leg. A. Weigel(009)”   Diagnosis.Length 3.0– 3.3 mm. Dorsum dark reddish brown ( Fig. 19A). Pronotum with uniform crescent-shaped punctures. Elytra shiny, spaces between ground punctation smooth. Mentumwith dense microsculpture and coarse punctures ( Fig. 20A). Posterior tentorial pits not distinctly depressed ( Fig. 20A). Prosternum tectiform medially; lateral portion without ridge and shagreened; prosternal process deeply notched posteriorly ( Fig. 20B). Antennal groove moderate in size ( Fig. 20B). Mesoventral plate spindle-shaped ( Fig. 20C). Arcuate ridge of metaventrite strongly bent backwards and distinct ( Fig. 20C). Lateral areas of metaventrite with scattered coarse punctures ( Fig. 20C). First abdominal ventrite with some longitudinal sculpture basally ( Fig. 20D). Male genitalia( Fig. 19D–G): paramere slightly expanded and obliquely truncate apically; inner face of paramere without fringe of setae ( Fig. 19D). Median lobe widest in basal third and gradually narrowing towards apex ( Fig. 19E).   Redescription. Form and Colour( Fig. 19A–C). Total length 3.0– 3.3 mm; maximum width 1.7–2.1 mm. Body broadly oval, not parallel-sided in the middle, moderately convex. Dorsum dark reddish brown and shiny. Maxillary and labial palpi yellowish brown; antennae yellowish brown with club darker. Ventral surface reddish brown to reddish black, legs reddish brown.  Head.Dorsal surface with uniformly dense and coarse crescent-shaped punctures; interstices between punctures smooth. Anterior margin of clypeus with a marginal bead. Eyes of moderate size, separated by ca. 5× the width of one eye. Mentumsubtrapezoid, ca. 2.0× as wide as long, slightly depressed anteromedially; anterior margin of mentum slightly concave; with dense transverse microsculpture and coarse punctures ( Fig. 20A). Posterior tentorial pits without distinct depressions. Antennae with 9 antennomeres; antennal club (antennomeres 7–9) compact and densely pubescent. Maxillary palpomere 2 strongly swollen in apical half, longer than palpomere 3; palpomere 4 almost symmetrical, slightly longer than palpomere 3. Each maxilla with a sucking-disc shaped appendage in male.   FIGURE 19.  Peltocercyon vividus( d'Orchymont, 1925),  comb. nov.(specimen from Selangor, Malaysia). A–C:habitus. D–G:male genitalia. A:dorsal view. B:lateral view. C:ventral view. D:aedeagus. E:median lobe. F:tegmen, G:sternite 9. Scale bars 0.5 mm.  Thorax.Pronotum widest posteriorly, gradually narrowed anteriad, with finer and sparser crescent-shape punctures than those on head. Lateral margins of pronotum narrowly rimmed, the rim overlapping anterior and posterior corners, anterior and almost whole posterior margin without rim. Prosternum gradually raised at middle portion and tectiform medially, with sharp median carina; lateral portion of prosternum without ridge and shagreened; prosternal process deeply notched posteriorly ( Fig. 20B). Antennal grooves moderate in size, outer lateral margin moderately convex ( Fig. 20B). Mesoventral plate spindle-shaped and elongate, surface slightly convex and shining; ca. 5–6 × as long as wide, posterior apex overlapping the anterior ridge of metaventrite in a single point ( Fig. 20C). Scutellar shield triangular, longer than wide, with punctures finer than those on pronotum. Elytra widest at anterior third; each elytron with 10 rows of punctate striae, striae moderately impressed; striae 6, 8 and 9 not reaching anterior margin of elytron; stria 10 short, only ending at posterior third of elytron; intervals of striae flat, with fine ground punctures, intervals between punctures smooth. Epipleuron wedge-shaped and strongly oblique at anterior half of elytron. Central area of metaventrite uniformly punctate and glabrous, lateral areas of metaventrite densely pubescent and with some coarse punctures; anterior ridge of metaventrite strongly bent backwards at anterolateral corner and forming an arcuate ridge; metaventrite with complete femoral lines crossing the anterolateral arcuate ridges and reaching anterolateral corners of metaventrite ( Fig. 20C). Anterior ridge of metaventrite continuous with the arcuate ridge at the crossing point ( Fig. 20C).   FIGURE 20.SEM photos of  Peltocercyon vividus( d'Orchymont, 1925) A:mentum and posterior tentorial pits of head. B:ventral view of prothorax. C:mesoventral plate and metaventrite. D:abdominal ventrites.  Legs.Profemora bare ventrally, with very fine punctures; mesofemora with coarser setiferous punctures than those on metafemora. Tibiae with small lateral spines. Tarsi with sparse gold ventral setae, first metatarsomere about as long as metatarsomeres 2–3 combined.  Abdomen.Abdominal ventrites densely pubescent. First ventrite sharply carinate medially, with a series of short longitudinal sculptures basally ( Fig. 20D), more rough than other ventrites.  Male genitalia.Paramere widest basally, slightly expanded and obliquely truncate apically; inner face of paramere without fringe of setae ( Fig. 19D, F). Phallobase shorter than parameres; nearly parallel sided, manubrium gradually narrowed and asymmetrical at the base ( Fig. 19D, F). Median lobe widest in basal third, gradually narrowing towards apex; gonopore triangular, situated subapically ( Fig. 19E). Median projection of sternite 9 slender and rounded basally; lateral struts slightly longer than median portion ( Fig. 19G).   Biology.Occurs in forests. Based on the label data, adults seem to be attracted to fresh and decaying bamboo shoots.   Remarks.This species is similar to  P. basirugosus  sp. nov.in form and colour and can be distinguished from it by depressed lateral portions of prosternum with shagreen ( Fig. 20B) (smooth in  P. basirugosus  sp. nov.( Fig. 6B)), anterior ridge of metaventrite continuous with the arcuate ridge at the crossing point of femoral line ( Fig. 20C) (discontinuous with the arcuate ridge in  P. basirugosus  sp. nov.( Fig. 6D)), and the paramere only slightly expanded apically ( Fig. 19F) (paramere strongly expanded apically in  P. basirugosus  sp. nov.( Fig. 5F)).   Distribution( Fig.43). Vietnam( Hoa Binh), Malaysia( Selangor), Thailand( Mae Hong Son), Indonesia( North Sulawesi). [318,647,903,927] Vietnam Hoa Binh 36 37 1 Hoa Binh IRSNB Coll. R. I. Sc. N. B & Coll. R. I. Sc. Vietnam Hoa Binh 36 37 1 Hoa Binh holotype IRSNB Vietnam Hoa Binh 36 37 1 1 Hoa Binh paratype 2007-08-21 NMP Malaysia 3.3255556 Ulu Gombak 21 101.75445 36 37 6 Selangor 2006-08-01 NMP Thailand Pang Mapha dist. Ban Pha Mon Pang Mapha 36 37 5 Mae Hong Son 2002-05-11 2002-05-21 2002-05-11 NHMB Vit KubAn Laos 750 19.583334 Louangphra-bang 1271 101.96667 36 37 5 1 4 2009-02-21 NMEG A. Weigel Indonesia 550 1.0972222 Boyong Atas 21 124.42389 36 37 1 1