Dactylosternum corbetti Balfour-Browne 1942
Creators: name: Mai, Zuqi
name: Hu, Jian
name: Minoshima, Yûsuke N.
name: Jia, Fenglong
name: Fikáček, Martin
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Hydrophilidae
Dactylosternum
Dactylosternum corbetti

description: Dactylosternum corbetti Balfour-Browne, 1942
(Figs. 2, 21, 46, 50, 68)
Dactylosternum corbetti Balfour-Browne, 1942: 860. Type locality: Peninsular Malaysia
Type material: not examined.
Material examined. CHINA: Guangdong: 1 male (SYSU), Shenzhen, Dapeng District, Shenshuitian, 22°38′36″N 114°26′16″E, 40 m, in the rotten wood, 23.VII.2019, Liang, Yang, Jiang & Ji leg.; 4 spec. (SYSU), Shenzhen, Dapeng District, Jingui Village, Xintang, 22°39′35″N 114°23′10″E, 62 m, 15.V.2019, Xie & Xiang leg.; 17 spec. (SYSU), Taishan Prefecture, Shangchuan Island, Hening Village, 21°43′59″N 112°46′35″E, 0 m, 18.I.2019, Jia & Liang leg. Hong Kong: 1 male (IZCAS), Tai Po District, Sha Lo Tung 187 m, 22.47578°N, 114.18192°E, 14.iv. 2013, Lin Mei-ying leg. Macao: 12 spec. (SYSU), Dangzai Mangrove Reserves, 22°8′24″N 113°33′11″E, 12 m, in the rotten banana tree, 16.I.2021, Jia & Mai leg.
Diagnosis. Length 2.9–3.8 mm. Body elongate oval, anterior half of elytra nearly parallel-sided (Fig. 2), moderately convex. Dorsal black. Anterior margin of clypeus without marginal rim. Vertex, pronotum and elytron with microsculpture consisting of punctures connected to two short diverging lines forming a flying-bird-like impression, those impressions connected to others in a loose reticulation (Fig. 46). Antenna yellow-brown, club compact. Elytron with 10 distinct rows of serial punctures, all nearly reaching elytral base. Aedeagus (Fig. 21): phallobase rather shorter than parameres; parameres slender and straight; outer margin of median lobe nearly parallel-sided, truncate and slightly concave apically, gonopore situated apically.
Redescription. Total length 2.9–3.8 mm; maximum width 1.7–2.2 mm; body oblong oval, moderately convex.
Coloration. Dorsal black, with lateral margin of elytron slightly paler (Fig. 2). Ventral black. Legs and mouthparts reddish brown. Maxillary palps and antenna yellow brown.
Head. Clypeus weakly convex, surface with microsculpture consisting of two short diverging lines connected to each ground pucture, forming a flying-bird-like impression, those impressions connected to others in a loose reticulation. Anterior margin of clypeus without marginal rim. Frons with punctures sparser than those on clypeus. Eyes small, nearly semicircular in dorsal view, separated by ca. 6× as width as one eye, distinctly emarginate anteriorly in lateral view, smooth medially. Maxilla with basistipes bearing sparse long setae. Mentum transverse, ca. 1.25× as wide as long, widest between anterolateral corners, slightly narrowing posteriorly, bearing sparse setae, strongly impressed anteromedially, lateral sides with series of fine setae. Submentum yellow-brown, pubescent. Labial palps rather stout, palpomere 1 minute, palpomere 2 strongly widened distally, with dense brush of long yellow setae on its inner face and distal margin, palpomere 3 longer than other ones. Antennal scapus longest, rather thick, ca. 2× as long as antennomeres 2–6 combined, antennomere 3 thin and almost as long as pedicellus, antennomeres 4 and 5 slightly widening distally, cupula (antennomere 6) short and wide, without any seta, club densely pubescent, with few long setae, compact, ca. 1.6× as long as wide.
Prothorax. Pronotum moderately convex, widest basally, arcuately narrowing anteriorly, anterolateral angles obtusely rounded, posterolateral angles with blunt corners, anterior and lateral margins with narrow marginal bead, surface with punctures similar to those on vertex (Fig. 46). Prosternum weakly tectiform medially, 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 moderately convex, elytral margin slightly explanate in posterior half, sutural stria deeply impressed in posterior half; each elytron with 10 longitudinal serial punctures, all nearly reaching elytral base, the three inner series deeply impressed in posterior half; elytral intervals with flying-bird-like fine punctures sparser than those on pronotum between series (Fig. 50). Epipleuron very wide and strongly oblique, ending at elytral apex, pubescent. Mesoventrite fused to mesepisterna, strongly elevated posteromedially to form an arrowhead-shaped process.
Legs. Reddish to yellowish brown, rather short, femora and tibiae flattened. Procoxae globular, pubescent; profemora without pubescence ventrally; protibiae cylindrical, with strong apical spurs and a sparse series of lateral stout spines; protarsomeres pubescent ventrally. Mesocoxae pubescent, separated by metaventral process. Metacoxae pubescent, contiguous medially. Ventral surface of meso- and metafemora without pubescence, with sparse punctures and microsculptures; meso- and metatibiae flattened, with short spines along lateral and mesal faces, and two apical spurs; meso- and metatarsomeres with sparse pubescence ventrally, almost equal in length.
Abdomen. Pubescent, ventrite 1 with complete median carina, other ventrites uniformly convex, with complete marginal bead. Posterior margin of ventrite 5 rounded, with a stria in front of the marginal bead.
Male genitalia (Fig. 21). Aedeagus about 0.7 mm long, ca. 2.1× as long as wide. Phallobase ca. 0.3× as long as parameres. Parameres straight, gradually narrowing towards apex. Median lobe a little shorter than parameres, ca. 0.7× as long as parameres, widest basally, outer margin nearly parallel-sided, truncate and slightly concave apically, gonopore situated at apex.
Biology (Figs. 65, 68). Living in rotting plant tissues, like rotten wood and rotten banana stems.
Distribution. China (Guangdong, Hong Kong, Macao, Taiwan). Outside of China known from Malaysia and the Philippines (Hansen 1999).
description: Published as part of Mai, Zuqi, Hu, Jian, Minoshima, Yûsuke N., Jia, Fenglong & Fikáček, Martin, 2022, Review of Dactylosternum Wollaston, 1854 from China and Japan (Coleoptera, Hydrophilidae, Sphaeridiinae), pp. 269-300 in Zootaxa 5091 (2) on pages 274-275, DOI: 10.11646/zootaxa.5091.2.3, http://zenodo.org/record/5843837