Peltocercyon carnarius Mai, Jia, Ryndevich

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 : 16-19

Peltocercyon carnarius Mai, Jia, Ryndevich , Angus & Fikáček sp. nov.

Figs 2C , 7A–G , 8A–D

Type material examined. Holotype: male ( NHMUK), “ Fort de Kock , W. Sumatra, E. Jacobson. / B.M. 1926-2 // Cercyon carnarius Kn. / det. A. Knisch, 1926” Paratypes: INDONESIA: 1 male, 1 female ( NHMUK), “ Fort de Kock, W. Sumatra, E. Jacobson. / B.M. 1926-91// Fort de Kock , (Sumatra) 920 M / leg. E. Jacobson. // Coll. A. Knisch / Cercyon carnarius Kn. / COTYPUS // Paratype ” ; 4 females ( NHMUK), “Fort de Kock, W. Sumatra, E. Jacobson. B.M. 1926-2.” 1 female ( NHMUK), “ Fort de Kock , (Sumatra) 920M / leg. E. Jacobson. // Coll. A. Knisch / COTYPUS// Paratype.” ; 1 spec. ( MZB), “MZB.COLE.174.998 / INDONESIA, EAST KALIMANTAN, SAMBOJA / 18-01-2025 / Coll. Anang S. Budi, Dhian Dwibadra, D. Peggie / Baited Pitfall Trap.”; PHILPPINES : 16 spec. ( NMP, ADMU), “PHILPPINES: Mindanao isl., Davao Or. Prov., Mt. Hamiguitan , Research Base , alt. 390–440 m / 6°44’07.44’’N 126°08’30.14’’E, 16–23.II.2017, Damaška, Hiřman, Šípek, VondrÁček lgt. // pitfall traps with pork liver and shrimps near research base. / Open area near forest and ferns. Propylenglycole, then transferred to 96% EtOH” ; 34 spec. ( NMP), “PHILPPINES: Mindanao isl., Davao City Prov., Mt. Malambo , Busay Resort , alt. 1200 m, 7°28’52.83’’N 125°15’43.31’’E, 15–28.II.2017, Damaška, Hiřman, Šípek, VondrÁček lgt. // pitfall traps with squid around resort and patches of forest” ; MALAYSIA: 1 female ( NMW), “ Malaysia. Sabah. Batu Punggul Resort env., / 24.VI. – 1.VII.1996. 11f. / intercept trap ” ; 1 spec. ( NMW), “MALAYSIA: Sarawak / ca. 80km S Kuching / Mt. Penrissen , 1000 m / III.1994. Kodada leg.” ; 31 spec. ( NHMUK), “ Malaysia: 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: 1205 NHMUK Loan” ; 20 spec. ( NMP), “ Malaysia: Borneo, Sabah, Keningau , Mt. Trus Madi , Trus Madi Entomology Camp , baited pitfall traps, 1200m, 26–29.VIII.2024, 5.44423N, 116.45129E, BH. Ho”

DNA vouchers. MZ200: 1 male. ( NMP), “PHILPPINES: Mindanao isl., Davao Or. Prov., Mt. Hamiguitan , Research Base , alt. 390–440 m / 6°44’07.44’’N 126°08’30.14’’E, 16–23.II.2017, Damaška , Hiřman , Šípek , VondrÁček lgt. // pitfall traps with pork liver and shrimps near research base. / Open area near forest and ferns. Propylenglycole , then transferred to 96% EtOH // DNA isolate: DNA extraction: MF200, DNA extract stored at Department of Entomology , National Museum , Prague ”

Diagnosis. Length 3.1–3.6 mm. Dorsum uniformly yellowish brown to reddish brown ( Fig. 7A ). Pronotum with uniform crescent-shaped punctures. Elytra shiny, spaces between punctation smooth. Mentum with sparse and fine punctures ( Fig. 8A ). Head with posterior tentorial pits forming two large depressions ( Fig. 8A ). Prosternum slightly bulging medially, with a curved fine ridge on each side of the median carina, lateral areas smooth; prosternal process pointed posteriorly ( Fig. 8B ). Antennal groove broad ( Fig. 8D ). Mesoventral plate spindle-shaped ( Fig. 8C ). Arcuate ridge of metaventrite strongly bent backwards and distinct ( Fig. 8C ). Lateral area of metaventrite without coarse punctures ( Fig. 8C ). First abdominal ventrite without longitudinal sculptures basally ( Fig. 8D ). Male genitalia ( Fig. 7D–G ): 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. 7D ). Median lobe nearly parallel sided, narrowed subapically; apex bluntly pointed ( Fig. 7C ).

Description. Form and Colour ( Fig. 7A–C ). Total length 3.1–3.5 mm; maximum width 1.8–2.1 mm. Body broadly oval, not parallel-sided in the middle, moderately convex. Dorsum shiny, yellowish brown to reddish brown. Maxillary palpi and labial palpi yellowish brown; antennae yellowish brown with club darker. Ventral surface yellowish brown to reddish brown.

Head. Dorsal surface with uniformly dense and fine 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. Mentum subtrapezoid, ca. 1.5× as wide as long, moderately depressed anteromedially; anterior margin of mentum slightly concave; with fine and sparse punctures ( Fig. 8A ). Posterior tentorial pits strongly concave, forming two large depressions ( Fig. 8A ). 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 similar punctures to 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 slightly bulging in the middle, but with a sharp median carina, with a pair of fine curved ridges on both sides of the median carina; prosternum smooth throughout; prosternal process pointed posteriorly ( Fig. 8B ). Antennal grooves broad, outer lateral margin strongly convex ( Fig. 8B ). Mesoventral plate spindle-shaped and elongate, surface slightly convex and shining; ca. 7–8 × as long as wide, posterior apex overlapping the anterior ridge of metaventrite in a single point ( Fig. 8C ). Scutellar shield triangular, longer than wide, with punctures finer than those on pronotum. Elytra widest in 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 bare, lateral areas of metaventrite densely pubescent, without coarse punctures; anterior ridge of metaventrite strongly bent backwards at anterolateral corner and forming an arcuate ridge; femoral lines complete, crossing anterolateral arcuate ridges and reaching anterolateral corners of metaventrite ( Fig. 8C ). Anterior ridge of metaventrite continuous with the arcuate ridge at the crossing point of femoral line, with a small pit at each crossing point ( Fig. 8C ).

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 longitudinal sculptures basally ( Fig. 8D ).

Male genitalia. Paramere widest basally, gradually narrowing towards apical fourth, slightly widened subapically and then gradually narrowing towards apex; apex of paramere bluntly pointed, slightly curved inwards; inner face of paramere with a fringe of long setae subapically and several apical setae ( Fig. 7D, F ). Phallobase slightly shorter than parameres; nearly parallel sided, manubrium gradually narrowed and asymmetrical at the base ( Fig. 7F ). Median lobe widest in the middle, parallel sided, narrowed subapically, apex bluntly pointed; gonopore triangular, situated subapically ( Fig. 7E ). Median projection of sternite 9 narrowed medially, slightly widen anteriorly and rounded basally; lateral struts slightly longer than median portion ( Fig. 7G ).

Biology. Occurs in forests. Some specimens were attracted to pitfall traps baited with meat and squid.

Etymology. This is an undescribed species which A. Knisch intended to name Cercyon carnarius . The species name is accepted by us.

Remarks. This new species can be easily distinguished from other species of this genus by the combination of (1) the middle portion of the prosternum bulging, with a pair of fine curved ridges on each side ( Fig. 8B ), (2) posterior tentorial pits of head forming two large depressions ( Fig. 8A ).

Distribution ( Fig. 45 ). Indonesia (West Sumatra, East Kalimantan), Philippines (Mindanao), Malaysia (Sabah, Sarawak).

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 7. Peltocercyon carnarius sp. nov. (paratype from Mindanao, Philippines). 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.

FIGURE 8. SEM photos of Peltocercyon carnarius sp. nov. A: mentum and posterior tentorial pits of head. B: ventral view of prothorax. C: mesoventral plate and metaventrite. D: abdominal ventrites.

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