Dactylosternum pui Jia, 2002

Mai, Zuqi, Hu, Jian, Minoshima, Yûsuke N., Jia, Fenglong & Fikáček, Martin, 2022, Review of Dactylosternum Wollaston, 1854 from China and Japan (Coleoptera, Hydrophilidae, Sphaeridiinae), Zootaxa 5091 (2), pp. 269-300 : 281-282

Dactylosternum pui Jia, 2002

( Figs. 4 , 22 , 41, 43 )

Dactylosternum pui Jia, 2002: 75 . Type locality: China (Guangxi)

Type material examined. HOLOTYPE: male ( IZCAS), Guangxi, Napo, Nonghua , 750 m, 18.VIII.1998, Fusheng Huang leg. PARATYPE: 3 females ( SYSU): same information as the holotype .

Diagnosis. Length 3.2–3.4 mm, widest in the middle. Body broadly oval, body outline not parallel-sided ( Fig. 4 ), strongly convex. Body reddish brown to piceous brown. Antenna yellow-brown with club black, club loosely segmented. Anterior margin of clypeus pubescent, without marginal rim. Elytron with sutural stria reaching half of elytra, with 9 serial punctures, series 1 reaching basal third, series 2–3 reaching basal half, series 4–9 nearly reaching elytral base. Ventral surface of mesofemora bearing dense pubescence. Aedeagus ( Fig. 22 ): Phallobase a little shorter than parameres ( Jia 2002). Apex of parameres projecting slightly outwards. Median lobe a little shorter than parameres. Gonopore rounded, subapically.

Redescription. Total length 3.2–3.4 mm; maximum width 2.0– 2.1 mm; body broadly oval, strongly convex.

Coloration. Reddish brown to piceous brown ( Fig. 4 ), Ventral with the same color as dorsal; mouthparts, maxillary palps and labial palps reddish yellow; antenna reddish yellow with club black; legs with the same color as ventral but tarsomeres somewhat paler.

Head. Clypeus weakly convex, surface with sparse and moderately strong punctures, anterior portion with denser punctures. Interstices between punctures smooth. Anterior margin of clypeus without marginal rim, bearing pubescence. Frons with punctures similar to those on clypeus, posterior margin of vertex with microsculpture between punctures. Eyes of moderate size, nearly semicircular in dorsal view, separated by ca. 5.5× of the width of one eye, distinctly emarginate anteriorly in lateral view, smooth medially. Maxilla with basistipes bearing sparse long setae. Mentum transverse, strongly impressed anteromedially, lateral sides with series of fine setae. Submentum yellowbrown pubescent. Labial palps rather stout. Antennal scapus longest, rather thick, ca. 3.5× as long as pedicellus, antennomere 3 thin and a little shorter than pedicellus, antennomeres 4 and 5 almost equal in length, slightly widening distally, without any seta, club densely pubescent, with few long setae, loosely segmented.

Prothorax. Pronotum moderately convex, widest basally, arcuately narrowed in front, with punctures similar to those on vertex ( Fig. 43 ), posterior margin slightly arcuate, with narrow marginal bead. Prosternum strongly tectiform, with median carina and a distinct tooth anteromedially.

Meso- and metathorax. Scutellum slightly longer than wide, apex rounded, in shape of isosceles triangle, with punctures similar to those on pronotum. Elytron ca. 1.45× as wide as long, highly convex, sutural stria reaching half of elytra posteriorly, with 7 series of pigmented spots; each elytron with 9 longitudinal series of impressed punctures, with shallow fine ground punctures on intervals; series 1 reaching basal third, series 2–3 reaching basal half, series 4–9 nearly reaching elytral base. Inner 3 series with smaller punctures than outer seriesl; punctures in outer series becoming coarser gradually; the outer 4 serial punctures coarser and stronger than the inner 6 serial punctures; intervals of serial punctures with two sizes of punctures, the finer punctures similar to those on pronotum, the coarser punctures almost as coarse as those of the series that make it more or less difficult to separate the series posteriorly and laterally.

Legs. Reddish brown to piceous brown. Procoxae globular, pubescent; profemora bearing dense pubescence throughout; protarsomeres pubescent ventrally. Mesofemora with dense pubescence ( Fig. 43 ). Metafemora without pubescence, with sparse microsculpture; meso- and metatarsomeres with sparse pubescence ventrally.

Abdomen. Pubescent, ventrite 1 with complete median carina, other ventrites uniformly convex, with complete marginal bead. Posterior margin of ventrite 5 rounded, without stria.

Male genitalia ( Fig. 22 ). Aedeagus about 0.7 mm long. Phallobase slightly shorter than parameres. Parameres apex projecting slightly outwards, gradually narrowing. Median lobe ca. 0.8× as long as parameres, apex rounded, gonopore rounded, situated at midlength.

Biology. Unknown.

Distribution. China (Guangxi).

Figures

FIGURES 1–4. Habitus of Dactylosternum spp. from China and Japan. 1: D. abdominale (Fabricius, 1792), 2: D. corbetti Balfour-Browne, 1942, 3: D. nanlingensis sp. nov., 4: D. pui Jia, 2002

FIGURES 20–24. Aedeagus of Dactylosternum spp. 20: D. abdominale (specimen from Yonaguni-jima Island, Japan, dorsal view, showing variation of apex of paramera) 21: D. corbetti, 22: D. pui (phallobase missing), 23: D. nanlingensis sp. nov., paratype (23a: ventral view, 23b: dorsal view), 24: D. hydrophiloides

FIGURES 39–47. Morphology characters of Dactylosternum spp. SEM micrographs. 39–40: antennal club (39: D. nanlingensis sp. nov., 40: D. abdominale), 41–42: ventral surface of mesofemora (41: D. pui, 42: D. nanlingensis sp. nov.), 43–47: punctures on pronotum (43: D. pui, 44: D. songxiaobini sp. nov. (surface with two sizes of punctures, the blue arrow indicates the coarser puncture, the yellow arrow indicates the finer puncture), 45: D. nanlingensis sp. nov., 46: D. corbetti (arrow indicates two short divergent lines connected with a puncture), 47: D. abdominale (arrow indicates mesh-like microsculpture between punctures))