Peltocercyon coomani d'Orchymont, 1925

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 : 19-24

Peltocercyon coomani d'Orchymont, 1925

Figs 2B , 9A–I , 10A–E , 33A–C , 39A–D .

Peltocercyon Coomani Orchymont, 1925d: 285 . Type locality: Vietnam, Tonkin, Hoa Binh.

Type material examined. Holotype ( Fig. 33A–C ): male ( IRSNB), “ Hoa Binh / Tonkin / de Cooman // Peltocercyon Coomani Orchymont. // TYPE” . Paratypes: 1 spec. ( NHMUK), “ Mt. Matang / W. Sarawak. / G.E. Bryant. / 16- 30 xii.13 // G. Bryant Coll. // 1919-147 // A. d'Orchymont det. / Peltocercyon / Coomani / d'Orchymont // Cotype / Paratype (handwriting)” ; 1 spec. ( NHMUK), “Quop, / W. Sarawak. / II-III.1914 / G. E. Bryant // G. Bryant Coll .

/ 1919-147 // Paratype // Paratype (handwriting)”. 1 spec. ( IRSNB), “ Coll. R.I.Sc.N.B. / N. Vietnam Tonkin / Hoa Binh / de Cooman leg. // Para- / type”

Additional material: CHINA: Hainan : 1 female ( SYSU), “ Hainan Prov., Wuzhishan City, Shuimanxiang Village, Wuzhishan Natural Reserve , jackfruit trap, 772 m, 18.9062°N 109.6813°E, 10.II.2023, Zu-Qi Mai leg.” ; 1 male ( NMP), “ Hainan isl. [MF23] / Bawangling Nat. Forest Park/ 12.3 km SEE of Baotie / 19°5.20′N / 109°11.80′E / 1050 m, 8.v.2011; FikÁček // rotting banana trunks at the banks of a stream amid the primary mountain forest. // PELTOCERCYON / coomani (hw) / det. M. FikÁček 2011.” ; Yunnan: 1 male ( SYSU), “ Baoshan, Longyang District, Mangkuan Town , Baihualing Mt. , Zaotanghe / in leaf litter on the side of a forest stream, 25.308791°N 98.793922°E, 1519 m, 11.Ⅴ.2021, Zhuo-Yin Jiang, Bao-Ping Huang & Zu-Qi Mai leg.” ; 5 spec. ( SYSU), “ Baoshan, Longyang District, Mangkuan Town , Baihualing Mt. , Hanlongzhai village , jackfruit trap, 25.3006°N 98.8004°E, 1564 m, 23.VIII.2022, Yu-Chen Zheng, Yue-Zheng Tu & Zu-Qi Mai leg.” ; 1 female ( SYSU), “ Dehong Dai and Jingpo Autonomous Prefecture, Mengbanaxi Rare Garden (勐ƋDZƀẅ奇园), in rotten jackfruit, 11.VIII. 2022, 892 m, 98.5885°E 24.4295°N, Yu-Chen Zheng & Zu-Qi Mai leg.” ; 9 spec. ( SYSU), “ Dehong Dai and Jingpo Autonomous Prefecture , Yingjiang County, Tongbiguan Town , Jinzhuzhai village , jackfruit trap, 1281 m, 97.5993°E 24.6146°N, 24.VIII.2022, Yu-Chen Zheng, Yue-Zheng Tu & Zu-Qi Mai leg.” ; 101 spec. ( SYSU), “ Dehong Dai and Jingpo Autonomous Prefecture , Yingjiang County, Tongbiguan , Xima Town , Hulukou , Xingyun Secondary power station (AE云二ãDzü), in rotten jackfruits and rotten bananas, 24.7759°N 97.6582°E, 1021 m, 18–20.VIII.2022, Yu-Chen Zheng, Yue-Zheng Tu & Zu-Qi Mai leg.” ; 1 female ( SYSU), “ Xishuangbanna, Botanical Garden , in rotten jackfruit, 556 m, 21.9278°N 101.2560°E, 26℃, Bao-Ping Huang leg.” ; 1 spec. ( NMEG), “CHINA: S-YUNNAN / (Xishuangbanna) / 20 km NW Jinghong // vic. Man Dian ( NNNR) / 22°07.80’N 100°40.05’E / 730 m / 23.Ⅴ.2008, GS / leg. A. Weigei, forest // COLLECTION A. SKALE, HOF / GERMANY” . LAOS: 1 male ( SYSU), “LAOS: Khammouane Prov., Ban Khoumkhan [Khun Kham], ( Nahin ), 300m, 3-5.vi.2008, 18º13.027′N 104º30.880′E, Solodovnikov & Pedersen/ (LAO08-11G). // disturbed primary rainforest, ZMUC collection, PELTOCERCYON / coomani (hw) / det. M. FikÁček 2013.” 4 spec. ( NMP), “LAOS: NE, Xieng Khouang 19°38.20’N 103°20.20’E / Phonsavan (30 km NE). / PHOU SANE Mt., 1420 m / 10–20.Ⅴ.2009, V. KubÁň leg. // secondary mountain forest / flight intercept trap ” ; 3 spec. ( NHMB), “LAOS-N ( Louangphra-bang ), 11–21.Ⅴ.2002, 19°35’N 101°58’E, THONG KHAN, 750 m, Vit KubÁň leg. // Collection Naturhistorisches Museum Basel” ; 3 spec. ( NHMB), “LAOS- N (Oudomxai) / 1–9.Ⅴ.2002, 1100 m / 20°45’N 103°09’E, OUDOM XAI (17 km NEE), Vit KubÁň leg. // Collection Naturhistorisches Museum Basel” ; 26 spec. ( NHMB), “LAOS, 1–18.Ⅴ.2001 / Bolikhamsai Prov., 18°21’N 105°08’E, Ban Nepe (8 km NE), 600 m, Vit KubÁň leg.” . 1 female ( NMP), “LAOS-NE, Houa Phan prov. / 20°13′09–19″N 103°59′54″– 104°00′03″E / 1480–1520 m / PHOU PANE Mt. , 2–22.VI.2011, Vit. KubÁň leg. MALAYSIA: 3 spec. ( NMP), “W. MALAYSIA: Selangor / Ulu Gombak field studies centre / 3°19’32’’N 101°45’16’’E (V7/07/2) in decaying Artocarpus fruit lgt. Damir Kovac, 24.VIII.2007 ” ; 5 spec. ( NMP), “W. MALAYSIA: Selangor / Ulu Gombak field studies centre / 3°19’32’’N 101°45’16’’E (V7/07/2) in decaying Artocarpus fruit lgt. Damir Kovac, 25.VIII.2007 ” . 1 male, 3 unsexed spec. ( NHMUK), “ SARAWAK: / 4th Division / Gn. Mulu NP // nr. Base / Camp / 50–100 m // alluvial / forest // litter// P. M. Hammond & J.E. Marshall / v-viii.1978 / B. M. 1978-49.” 1 spec. ( NHMUK), “ SARAWAK: / 4th Division / Gn. Mulu NP // nr. Camp / I / 150-200m // mixed / dipterocarp / forest litter // P. M. Hammond & J.E. Marshall / v-viii.1978 / B. M. 1978-49.” 2 spec. ( NHMUK), “ SARAWAK: / 4th Division / Gn. Mulu NP // Site A / 65m. // alluvial / forest / Pitfall / trap // iii.78.” ; 1 spec. ( NHMUK) “ Borneo, Sabah, Crocker Range, Kota Kinabalu-> Tambunam. Hanging carrion trap., 1240 m., IV.2013, 5°51'33.7'' N, 116°17'24.1'' E, B.H. Garner, H. Mendel, M.V.L. Barclay, A. Giusti ( NHMUK (E) 2013-58) EtOH vial: 1206 NHMUK Loan” . THAILAND: 1spec. ( NMP), “THAILAND: Mae Hong Son Pang Mapha dist., 7.5 km W of Soppong [= Pang Mapha] / Ban Rai env., 29.Ⅹ.2005 / Damir Kovac lgt. (V08/05) // in decaying “pumpking”-fruit ”; 4 spec. ( NMP), “THAILAND bor. Mae Hong Son Prov., Pangmapha distr. / btw. Soppong-Ban Nam Rin / 21.Ⅹ.2005, bamboo stump, D. Kovac lgt. B25/05 // in a whitish sap coming out of the bamboo stum”; 1 spec. ( NMEG), S-THAILAND, Surat Thani Prov., near Ban Sadet / 08°42’49’’N 098°53’44’’E /A. Skale, 17.8. 2016, 350 m” . INDONESIA: 1 spec. ( NHMUK), “ Fort de Kock, / W. Sumatra. / B.M. 1926-91 // Fort de Kock / (Sumatra) 920M / leg. E. Jacobson. ” 1 spec. ( NHMUK), “ Fort de Kock, / W. Sumatra. / B.M. 1926-91 // Fort de Kock / (Sumatra) 920M / leg. E. Jacobson. // Peltocercyon / coomani Orch. ” 1 spec. ( NHMUK), “ Fort de Koch / (Sumatra) 920M. / April 1924 / leg. E. Jacobson // Fort de Kock / W. Sumatra. / B.M. 1926-91 .

DNA vouchers. MF106: 1 spec. ( NMP), “W. MALAYSIA: Selangor / Ulu Gombak field studies centre / 3°19’32’’N 101°45’16’’E (V7/07/2) in decaying Artocarpus fruit lgt. Damir Kovac, 25.VIII.2007 // DNA isolate: DNA extraction: MF106, DNA extract stored at Department of Entomology , National Museum, Prague”; MF470 : 1 spec. ( NMP), “LAOS-NE, Houa Phan prov. / 20°13′09–19″N 103°59′54″– 104°00′03″E / 1480–1510 m / PHOU PANE Mt., 2–22.VI.2011, Vit. KubÁň leg. // DNA isolate: DNA extraction: MF470, DNA extract stored at Department of Entomology, National Museum, Prague”; MF205 : 1 spec. ( NMP), “ Hainan isl. [MF23] / Bawangling Nat. Forest Park / 12.3 km SEE of Baotie / 19°5.20′N / 109°11.80′E / 1050 m, 8.v.2011; FikÁček // rotting banana trunks at the banks of a stream amid the primary mountain forest. // DNA isolate: DNA extraction: MF205, DNA extract stored at Department of Entomology , National Museum, Prague” MZ184 : 1 spec. ( NHMUK) “ Borneo, Sabah, Crocker Range, Kota Kinabalu-> Tambunam. Hanging carrion trap., 1240 m., IV.2013, 5°51'33.7'' N, 116°17'24.1'' E, B.H. Garner, H. Mendel, M.V.L. Barclay, A. Giusti ( NHMUK (E) 2013-58) EtOH vial: 1206 NHMUK Loan // MZ184” .

Diagnosis. Length 2.8–3.1 mm. Dorsum reddish brown; elytron with or without a dark brown to black transverse or triangular patch lateromedially ( Fig. 9A, B, D, E ). Pronotum with uniform crescent-shaped punctures. Elytra shiny, spaces between ground punctation smooth. Mentum with sparse and fine punctures ( Fig. 10A ). Posterior tentorial pits of head moderately large, forming two depressions ( Fig. 10A ). Prosternum sharply carinate medially; lateral portion of prosternum smooth, demarcated from the middle portion by an oblique ridge; prosternal process deeply notched posteriorly ( Fig. 10B ). Antennal grooves narrow ( Fig. 10B ). Mesoventral plate subtriangular, posterior margin concave, broadly contacting the mesoventrite ( Fig. 10C ). Arcuate ridge of metaventrite distinct, strongly bent backwards ( Fig. 10D ). Lateral area of metaventrite without coarse punctures ( Fig. 10D ). First abdominal ventrite without longitudinal sculptures basally ( Fig. 10E ). Male genitalia ( Fig. 9F–I ): paramere slightly widened subapically and then gradually narrowing towards apex, apex bluntly pointed and slightly curved inwards; inner face of the paramere with a fringe of long setae subapically and with several apical setae ( Fig. 9F, H ). Median lobe nearly parallel sided, narrowed subapically; apex bluntly pointed ( Fig. 9G ).

Redescription. Form and Colour ( Fig. 9A–E ). Total length 2.8–3.1 mm; maximum width 1.7–2.1 mm. Body broadly oval, not parallel-sided in the middle, rather convex. Dorsum reddish brown and shiny. Elytron with a dark brown to black obliquely transverse patch across 5–10 striae lateromedially, some individuals without this kind of patch and almost uniform in colour, some elytron with a triangular brown to black patch lateromedially; sometimes dark reddish brown in anterior third and yellowish on posterior third, making elytron tricolored. Maxillary palpi and labial palpi yellowish brown; antennae yellowish brown with club dark brown. Ventral surface dark yellowish to reddish brown.

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 fine and sparse punctures ( Fig. 10A ). Posterior tentorial pits forming depressions ( Fig. 10A ). 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.

Thorax. Pronotum widest posteriorly, gradually narrowed anteriad, with coarser 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 all of posterior margin without rim. Prosternum sharply carinate and pubescent at middle portion; lateral portion of prosternum glabrous, demarcated from the middle portion by a distinct oblique ridge; prosternal process deeply notched posteriorly ( Fig. 10B ). Antennal groove narrow, outer lateral margin slightly convex ( Fig. 10B ). Mesoventral plate subtriangular and elongate, surface slightly concave and shining; ca. 3× as long as wide, gradually narrowing anteriorly; posterior margin concave, broadly contacting anterior ridge of metaventrite ( Fig. 10C ). 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 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 and without coarse punctures; anterior ridge of metaventrite strongly bent backwards at anterolateral corner and forming an arcuate ridge; metaventrite with complete femoral lines crossing anterolateral arcuate ridges and reaching anterolateral corners of metaventrite; anterior ridge of metaventrite continuous with the arcuate ridge at the crossing point, with a pit behind anterior ridge medially and a pit on each side at the crossing point of femoral line and anterolateral arcuate ridges ( Fig. 10D ).

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, more densely pubescent than other ventrites but without a series of short longitudinal sculptures basally ( Fig. 10E ).

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

Biology ( Fig. 39A–D ). Occurs in forests.Adults live in decaying plant material in rainforest and can be attracted in large numbers by fermented fruits such as rotting banana or jackfruit ( Artocarpus ).

Remarks. Very characteristic species, it can be easily recognized by the lateral portions of prosternum demarcated from the middle portion by a pair of oblique ridges ( Fig. 10B ) and the mesoventral plate subtriangular and broadly contacting anterior ridge of metaventrite ( Fig. 10C ). There is a lot of variation between individuals of this species, especially in the elytral coloration. Most individuals have a dark brown to black obliquely transverse patch across 5–10 striae lateromedially, but some individuals lack this kind of patch and are almost uniform in color, some have elytron with a triangular brown to black patch lateromedially.

Distribution ( Fig.42 ). China (Hainan, Yunnan), Indonesia (West Sumatra), Laos (Khammouane, Xiangkhouang, Luang Prabang, Bolikhamsai, Houaphanh), Vietnam (Hoa Binh), Thailand (Mae Hong Son, Surat Thani) Malaysia (Selangor, Sarawak), Indonesia (West Sumatra). New records for China, Laos, Thailand and Malaysia.

Figures

FIGURE 2. Morphology of Peltocercyon. A: ventral morphology of Peltocercyon splendidus droup.B: prosternum, mesoventral plate and metaventrite of Peltocercyon coomani d'Orchymont, 1925. C: prosternum, mesoventral plate and metaventrite of P. carnarius sp. nov. Abbreviations of morphological structures:AG – antennal groove; AR – arcuate ridge; ARM – anterior ridge of metaventrite; CAM – central area of the metaventrite; FAV – first abdominal ventrite; FL – femoral line; LAM – lateral area of the metaventrite; M – mentum; MP – mesoventral plate; PP – prosternal process; PR – prosternum; PTP – posterior tentorial pit; R – ridge on lateral portion of prosternum.

FIGURE 9. Peltocercyon coomani d'Orchymont, 1925. A–E: habitus (A–C: specimen from Yunnan, China. D: specimen from Hainan, China. E: holotype). F–I: 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.

FIGURE 10. SEM photos of Peltocercyon coomani d'Orchymont, 1925. 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 33. Holotypes of Peltocercyon coomani d'Orchymont, 1925 and Cercyon vividus d'Orchymont, 1925. A–C: Peltocercyon coomani d'Orchymont, 1925. D–F: Cercyon vividus d'Orchymont, 1925.A: dorsal view. B: lateral view. C: labels. D: dorsal view. E: ventral view. F: labels.

FIGURE 39. Habitats of Peltocercyon coomani d'Orchymont, 1925. A: Mountains in Yunnan, China. B: jackfruit trap in forest. C: adult in decaying jackfruit. D: adult in leaf litter.

FIGURE 42. Distribution map of species in Peltocercyon splendidus group.