Peltocercyon lunulatus ( Gemminger & Harold, 1868 )

Mai, Zuqi, Jia, Fenglong, Ryndevich, Sergey K., Angus, Robert, Minoshima, Yûsuke N., Fikáček, Martin & Růžička, Jan, 2025, Taxonomic Revision and Phylogeny of the Genus Peltocercyon d'Orchymont, 1925 (Coleoptera: Hydrophilidae: Megasternini), Zootaxa 5671 (1), pp. 1-74 : 30-34

Peltocercyon lunulatus ( Gemminger & Harold, 1868)

Figs 15A–I , 16A–E , 36A–D .

Cercyon lunigerum Motschulsky, 1863: 444 (primary homonym of Cercyon lunigerum Mannerheim, 1853 ). Type locality: Sri Lanka, Nuwara Eliya .

Cercyon lunulatus Gemminger & Harold, 1868: 497 (replacement name).

Peltocercyon lunulatus (Gemminger & Harold) : Hansen (1991: 247).

Material examined. SRI LANKA: 3 spec. ( NMP), “SRI LANKA/ Sinharaja forest reserve / M.Viklický leg., V.2001 ” . 1 male ( NHMUK), “ Ceylon. / G. Lewis. / 1910-320 // Dikoya. / 3,800 –4,200 feet. / 13–16.II.82” ; SINGAPORE: 4 spec. ( NHMUK), “ Singapore. / 22.xi-19.xii. 1915 / Dr. M. Cameron. / Brit. Mus. / 1932-121” . 6 spec. ( NHMUK), “ Singapore. / Wallace // Sharp Coll. / 1905-313.” 1 male ( NHMUK) “ Singapore. / G. J. Saunders. / B. M. 1929- 369. / Cercyon lunulatus G.-H. // J. Balfour-Brwone det.” 1 spec. ( NHMUK), “ Ceylon. / G. Lewis. / 1910-320 // Kitulgalle. / 1,700 ft. / 17–20.I.82 // Cercyon lunigerum Motsch ” ; 15 spec. ( NHMUK), “ Ceylon // Sharp Coll. / 1905-313.” LAOS: 4 spec. ( NMP), “LAOS bor. occ. / Louang Namtha; 8–17.III.2000 / Muang Singh vill.; Pak Beng, P. Kulík lgt.” ; 110 spec. ( NMP), “LAOS: N-VIENTIANE Prov. / VANG-VIENG, 300 m, 18°55’23’’N, 102°26’55’’ / 10–15.Ⅴ. & 01–06.VI.2001 / JIŘÍ KOLIBÁČ leg.” ; 11 spec. ( NMP), “LAOS-CE: Boli Kham Xai Prov. / Ban Nape (8 km NE); 600 m; 18°21’N 105°08’E; / PacholÁtko leg; 1–18.Ⅴ.2001 ” ; 2 spec. ( NHMB), “LAOS: S-UDOMXAI Prov. / PAX BENG, 450 m / 19°53’37’’N, 101°07’51’’E / 18–27.Ⅴ.2001 / JIŘÍ KOLIBÁČ leg.” ; 12 spec. ( NHMB), “LAOS, 1–18.Ⅴ.2001. / Bolikhamsai prov. / 18°21’N 105°08’E / Ban Nape (8 km NE), 600 m, Vit KubÁň leg.” . 1 spec. ( NMW), “LAOS centr., Bolikhamsai Prov. / BAN NAPE – Kaew Nua Pass , / 18.4. – 1.5.1998. alt. 600± 100 m, / N18°22.3, E105°09.1 ( GPS), / M. Strba & R. Hergovits leg.” MALAYSIA: 1 female ( NHMB), “MALAYSIA / Langkawi, Umg. Hotel / Berjaya , Rinderdung [= deer excrement] / U. Schmidt, 7–22.XI.2009 ” . MYANMAR: 1 male ( NMEG), “MYANMAR / Shan Highland, Mong Hkok , 02–09.2006 // coll. A. Skale Hof / Saale.” . VIETNAM: 2 spec. ( SYSU), “TONKIN / Hoa-Binh / leg. A. de cooman // Cercyon / lunulatus / Gem. Et Har.” . 3 spec. ( NMEG), “VIETNAM, N (Na Hang) / 160 km NNW Hanoi / NE env. of Na Hang / 03–13.VI.1996 / 150–200 m, NN, leg. A. Napolov & I. Roma // collection NATURKUNDE-MUSEUM ERFURT” ; 4 spec. ( NMEG), “N-VIETNAM Ninh Binh Pr. 90 km / SW Hanol Cuc Phuong NP prim. / res. ctr., 25.IV. 2012, 190 m, 20°14’N 105°42’E, LF, leg. A. Weigel ” ; 7 spec., “VIETNAM, N, Ninh Binh / Pr. 90 km SW Hanoi / Cuc PhuongNP, primat rescue centre, 25.IV // 2012, 190 m, 20°14’24’’N / 105°42’53’’E, leg. A. Weigel, light trap // collection NATURKUNDE-MUSEUM ERFURT” ; 1 male ( NHMUK), “ Hoa Binh / Tonkin / de Cooman // Adrewe s/ Bequest. / B.M. 1922-221 // A. D'Orchymont Det. / Cercyon / lunulatus ♂ / Gemm.-Har.” ; 5 spec. ( NHMUK), “ Hoa Binh / Tonkin / de Cooman // A. D'Orchymont Det. / Cercyon / lunulatus / Gemm.-Har. / G.C. Champion. / B.M. 1926-146.”; 1 spec. ( NMW), N-VIETNAM: 26. – 39.5.1996 / 160 km NNW Hanoi, 150–200 m / NE env. of Na Hang / leg. Napolov & Roma ” CHINA: Guangdong: 1 male, 2 females ( SYSU), “ Yangjiang City, Yangxi County, Hetang Village , in fresh cow dung in the open field, 10 m, 21.7334°N 111.4061°E, 7.II.2022, Zu-Qi Mai leg.” ; 15 spec. ( SYSU), “ Yangjiang City, Yangxi County, Xinxu Town , Hetang Village , in fresh cow dung in the open field, 11 m, 21.7255°N 111.4259°E, 23–24.Ⅰ.2023, Zu-Qi Mai leg.” Guangxi : 1 male ( SYSU), “ China: Guangxi Prov / Baise City , Jingxi County / Bangliang N. R. / alt. 600 m, 3-6-VIII-2010. / HUANG Jian-Hua leg.” CAMBODIA: 1 male ( NMP) , 5 spec. ( SYSU), “ Cambodia: Siem Reap / Khnar Sanday (light trap) / 13.59876°N 103.9467°E / 31 m / 28–31.Ⅰ.2024 / Zuqi Mai leg.” INDONESIA: 1 male ( NHMUK), “ Fort de Kock , W. Sumatra. / E. Jacobson. / B.M. 1926-2 // Knisch det. 1923 / Cercyon / lunulatus G.-H.” 1 spec. ( NHMUK), SULAWESI UNTARA / Minahasa / Lahe Tondaro / 10.i.85 // cow dung // R. Ent. Soc. Lond. / PROJECT WALLACE // B.M. 1985-10.” ; 1 spec. ( NMW), “INDONESIA .

SE – Sulawesi / Rawa Aops Nat. Park / Aopa Vill. 8 – 10.2. 1994 / leg. M. Strba & I. Jenis ”; 1 spec. ( NMW) N- SUMATRA 91 / Dolok Merangir / leg. Malicky 21.II.” INDIA: 1 spec. ( NMW), “NE-INDIA: Meghalay / W Garo Hills / Balphakram NP // 25°11’N 90°51’E / 300–500 m / 22. – 27.5.1996 / leg. Jendek & Sausa”; 1 spec. ( NMW), “NE India Meghalaya state / West Garo hills, reg. TURA / 5. –7.Ⅴ.1996, alt 700± 100 m // GPS N 25°30.7’ E 90°13.9’ (WGS 84) / E. Jendek & O. Šauša leg.” THAILAND: 1 spec. ( NMW), “S-THAILAND: Yala Distr. / Betong, Gg. Cang Dun vill. / 25.3. – 22.4.1993 / leg. Hora ”

DNA voucher. MF437: 1 spec. ( NMP), “ Muara Ritan, border of fields and rainforest in foothil near Belayan river / 00°24.0’N 116°03.1’E, 48 m / 5.xii.2011, HÁjek, Schneider & Votruba lgt. // DNA isolate: DNA extraction: MF437, DNA extract stored at Department of Entomology , National Museum, Prague ” .

Diagnosis. Length 3.0– 3.4 mm. Body broadly oval, broadest in the middle, moderately convex. Head black, with a median yellow brown spot; pronotum yellowish brown; elytra yellowish brown, with a continuous or discontinuous V-shaped black patch ( Fig. 15A–D ). Pronotum with uniform crescent-shape punctures. Elytra shiny, spaces between ground punctation smooth. Mentum with very sparse and fine punctures ( Fig. 16A ). Posterior tentorial pits not depressed. Prosternum tectiform medially; lateral portion with sparse and fine setae, without ridge; prosternal process pointed posteriorly ( Fig. 16B ). Antennal grooves broad ( Fig. 16B ). Mesoventral plate spindle-shaped ( Fig. 16C ). Arcuate ridge of metaventrite distinct, strongly bent backwards ( Fig. 16D ). Lateral areas of metaventrite without coarse punctures ( Fig. 16D ). First abdominal ventrite without longitudinal sculptures basally. ( Fig. 16E ). Male genitalia ( Fig. 15F–I ): paramere slightly widened subapically and then gradually narrowing towards apex, apex bluntly pointed and slightly curved outwards; inner face of paramere with a fringe of long setae subapically and few apical setae ( Fig. 15F, H ). Median lobe widest slightly above the middle, gradually narrowing towards apex; becoming slender subapically, apex obtusely pointed ( Fig. 15G ).

Redescription. Form and Colour ( Fig. 15A–E ). Total length 3.0– 3.4 mm; maximum width 1.6–1.8 mm. Body broadly oval, slightly parallel-sided in the middle, moderately convex. Dorsum shiny. Head black, with a median yellow brown spot; pronotum yellowish brown; elytra yellowish brown, with a V-shaped black patch across elytra medially; the size of the patch varies from complete to discontinuous or to just a few black spots. Maxillary and labial palpi yellowish brown; antennae yellowish brown with club dark brown. Ventral surface dark yellowish brown; legs paler.

Head. Dorsal surface with uniform dense and coarse crescent-shape 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. Mentum subtrapezoid, ca. 1.5× as wide as long, strongly depressed anteromedially; anterior margin of mentum slightly concave; with very sparse and fine punctures ( Fig. 16A ). Posterior tentorial pits not distinctly depressed. Antennae with 9 antennomeres; antennal club (antennomeres 7–9) compact and densely pubescent. Maxillary palpomere 2 moderately 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.

Thorax. Pronotum widest posteriorly, gradually narrowed anteriad, with crescent-shape punctures as 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; pubescent, without ridge; prosternal process pointed posteriorly ( Fig. 16B ). Antennal grooves broad, outer lateral margin strongly convex ( Fig. 16B ). Mesoventral plate narrowly elongate, surface slightly convex and shining; ca. 6.5–7× as long as wide, posterior apex overlapping the anterior ridge of metaventrite in a single point ( Fig. 16C ). Scutellar shield in shape of equilateral triangle, longer than wide, with punctures as 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 glabrous. Epipleuron wedge-shaped and strongly oblique at anterior half of elytron. Central area of metaventrite uniformly punctate and bare, lateral areas of metaventrite densely pubescent, without coarse punctures; anterior ridge of metaventrite strongly bent backwards at anterolateral corner and forming a distinct arcuate ridge; metaventrite with complete femoral lines crossing the arcuate ridges and reaching anterolateral corners of metaventrite; anterior ridge of metaventrite continuous with the arcuate ridge at the crossing point ( Fig. 16D ).

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, without series of short longitudinal sculptures basally ( Fig. 16E ).

Male genitalia. Paramere widest basally, gradually narrowing towards apical fourth and slightly widen apically, then gradually narrowing towards apex; apex of paramere bluntly pointed and slightly outwards; inner face of paramere with a fringe of long setae subapically and several apical setae ( Fig. 16F, H ). Phallobase slightly shorter than parameres; nearly parallel sided; manubrium gradually narrowed and asymmetrical at the base. Median lobe widest slightly above the middle, gradually narrowing towards apex; becoming slender subapically, apex obtusely pointed ( Fig. 16G ). Median projection of sternite 9 gradually narrowed anteriad and rounded basally; lateral struts slightly longer than median portion ( Fig. 16I ).

Biology ( Fig. 36A–D ). Peltocercyon lunulatus inhabits open environments and forest edges at lower altitudes (below 1000 m). Adults occur in fresh cow excrement and are more active during the day.

Remarks. This species is similar to the species of the Peltocercyon splendidus group in form and colour. It can be distinguished from these species by the black head with a median yellow brown spot (head black throughout in members of the P. splendidus group), pronotum yellowish brown throughout (pronotum with black patch in members of the P. splendidus group), elytra with a continuous or discontinuous V-shaped black patch across the disc and elytral interval 1 slightly darkened (each elytron with a large triangular black patch lateromedially, elytral interval 1 black from base to apex in members of the P. splendidus group).

Distribution ( Fig. 45 ). China (Guangdong, Guangxi), Indosnesia (West Sumatra, North Sulawesi, South East Sulawesi, East Kalimantan), India (Meghalaya), Thailand (Yala), Singapore, Sri Lanka, Vietnam (Hoa Binh), Laos (Luang Namtha), Malaysia (Langkawi), Cambodia (Siem Reap), Myanmar (Shan). New record for China, Laos, India, Malaysia, Cambodia, Thailand and Myanmar.

Figures

FIGURE 15. Peltocercyon lunulatus (Gemminger & Harold, 1868). A–E: habitus (A, C, D, E: specimens from Guangdong, China. B: specimen from Hoa Binh, Vietnam). F–I: male genitalia. A–C: dorsal view. D: lateral view. E: ventral view. F: aedeagus. G: median lobe. H: tegmen, I: sternite 9. Scale bars 0.5 mm.

FIGURE 16. SEM photos of Peltocercyon lunulatus. A: ventral view of head. B: ventral view of prothorax. C: mesoventral plate and central area of metaventrite. D: right portion of metaventrite. E: first abdominal ventrite.

FIGURE 36. Habitats of Peltocercyon lunulatus (Gemminger & Harold, 1868). A: open fallow field in Guangdong, China. B, C: living adults in fresh cattle excrement. D: open field in Siem Reap, Cambodia.

FIGURE 45. Distribution map of Peltocercyon lunulatus, P. carnarius sp. nov. and P. latifossus sp. nov.