Dactylosternum hydrophiloides
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 hydrophiloides

description: Dactylosternum hydrophiloides (MacLeay, 1825)
(Figs. 6, 18, 24, 51, 69)
Sphaeridium hydrophiloides MacLeay, 1825: 36. Type locality: Indonesia, Java.
For complete synonymy, see Hansen (1999)
Type material: not examined.
Material examined. CHINA: Guangdong: 6 spec. (SYSU), Fengkai County, Heishiding Natural Reserve, decaying pseudostem of banana, 5.VII.2014, Jia & Song leg.; 1 spec. (SYSU), Fengkai County, Heerkou, decaying bamboo, 15.VIII.2010, Jia leg.; 12 spec. (SYSU), Guangzhou, Guanzhou Island, pseudostem of banana, 26.VIII.2012, Song leg.; 4 spec. (SYSU), Guangzhou, Haizhu District, 12.VIII.2012, Song leg.; 4 spec. (SYSU), Shaoguan Prefecture, Ruyuan County, Danxiashan, Jinshiyan, 22. IV.2012, Jia & Liao leg.; 1 spec. (SYSU), Heshan Prefecture, 27. VIII.2002, Liu leg.; 1 spec. (SYSU), Heshan Prefecture, 22–24. IV.2002, Wen leg.; 1 spec. (SYSU), Guangzhou, Sun Yet-sen University, 20.VII.1997, Jia leg.; 1 spec. (SYSU), Guangzhou, 27.IX.1993, Liang leg.; 5 spec. (SYSU), Shipai, VII.1952, Chen leg. 1 spec. (SYSU), Guangzhou, IX.1964, Li leg.; 1 spec. (SYSU), Shenzhen, Futian District, Meilinyicun, 13.ii.2017, Huang & Mai leg.; Guangxi: 3 spec. (SYSU), Rongshui County, banana tree, 17.iii.1959, Wu leg.; 6 spec. (SYSU), Wuzhou, banana tree, 15.iii.1959, Guangx Team leg.; 3 spec. (SYSU), Longlin County, Jinzhongshan, VIII. 2014, Zhou leg.; 1 spec. (SYSU), Shiwandashan Forest Park, 267 m, light trap, 9.VII.2011, Song leg.; 1 spec. (IZCAS), Napo, Nonghua, 1000 m, 14.iv.1998, Li Wen-zhu leg.; Guizhou: 1 spec. (SYSU), Kuankuoshui, 746m, light trap, 9.VII.2010, Liu leg.; Hainan: 1 spec. (SYSU), Jianfengling, 9–10.V.2011, Zhao leg.; 1 spec. (SYSU), Jianfengling, light trap, 9.V.2011, Zhao leg.; 2 spec. (SYSU), Baishabanxi Natural Preservation Zone, 2–3.IX.2013, Xie leg.; 2 spec. (SYSU), Lingmushan, Lingmu Temple, 5–6.V.2011, Zhao leg.; 1 spec. (SYSU), Jianfengling, Tianchi, light trap, 26.VII.1983, He leg.; 1 spec. (SYSU), Jianfengling, Tianchi, light trap, 17.V.1985, Long leg.; Hong Kong: 1 spec. (SYSU), Hong Kong Island, VIII.1933, W. E. Hoffmann leg.; Yunnan: 1 male, 1 female (SYSU), Mengla County, Menglun Reservoir, 620 m, 16.V.2018, Qiu & Xu leg.; 9 spec. (SYSU), Mengla County, Nazhuo Village, pseudostem of banana, 700 m, 4.X.2010, Zhou leg.; Mengla County, 850 m, 3.V.1957, Wang leg.; 7 spec. (SYSU), Xishuangbanna, Nabanhe National Natural Reserve, Naban Village, 12.I.2004, Li & Tang leg.; 13 spec. (SYSU), Xishuangbanna, Nabanhe National Natural Reserve, Mandian, 11.I.2004, Li & Tang leg.; 3 spec. (SYSU), Xishuangbanna, Nabanhe National Natural Reserve, Manfei, 9.I.2004, Li & Tang leg.; 2 males, 2 females (SYSU), Xishuangbanna Botanical Garden, 5.VII. 2003, Hu & Tang leg.; 16 spec. (SYSU), Jiangdong County, Taizhong Town, 24°30′N 100°56′E, 1395 m, 15.IV.2015, Lin & Tang leg.; 2 spec. (SYSU) Jiangdong County, Taizhong Town, 25°10′N 98°16′E, 1516 m, 18.IV.2015, Lin & Tang leg.; 6 spec. (SYSU), Yuanjiang County, 500m, 12.V.1957, Liang leg.; 3 spec. (SYSU), Xishuangbanna, Jinghong Prefecture, Damenglong Town, 600 m, 29. IV.1957, Liu leg.; Xizang: 3 spec. (SYSU), Linzhi Prefecture, Motuo County, Yarang, 760 m, 19.VIII.2006, Bai leg.
Diagnosis. Length 5.7–8.1 mm. Body elongate oval, anterior half of elytra nearly parallel-sided (Fig. 6), weakly convex. Dorsal black, surface with fine punctures. Anterior margin of clypeus with distinct marginal rim (Fig. 18). Antenna yellow-brown, club compact. Elytron with sutural stria and 10 distinct rows of serial punctures, interstices of ground punctures with dense micropunctures, especially in posterior half (Fig. 51). Aedeagus (Fig. 24): Phallobase almost as long as parameres. Median lobe very short and wide, reaching only to the middle of parameres, gonopore situated subapically.
Redescription. Total length 5.7–8.1 mm; maximum width 3.5–4.0 mm; body elongate oval, weakly convex.
Coloration. Dorsal black, with lateral margin of elytron slightly paler (Fig. 6). Ventral black. Legs and mouthparts reddish brown. Maxillary palps and antenna yellowish brown.
Head. Clypeus weakly convex, surface with dense punctures, anterior portion with denser punctures. Interstices smooth, without microsculpture. Anterior margin of clypeus with distinct marginal rim (Fig. 18). Frons with punctures similar with those on clypeus. Eyes of moderate size, nearly semicircular in dorsal view, separated by ca. 5× the width of one eye, distinctly emarginate anteriorly in lateral view, smooth medially. Maxilla with basistipes glabrous. Mentum transverse, glabrous, widest between anterolateral corners, slightly narrowing posteriorly, strongly impressed anteromedially, lateral sides with series of fine setae. Submentum reddish 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. 7× 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, compact, ca. 2.5× as long as wide.
Prothorax. Pronotum moderately convex, widest basally, arcuately narrowed in front, anterolateral angles obtusely rounded, posterolateral angles almost rectangular, posterior margin slightly arcuate, anterior and lateral margins with narrow marginal bead, pronotum with punctation similar to those on vertex. Prosternum moderately tectiform medially, with median carina and a distinct tooth anteromedially.
Meso- and metathorax. Scutellum distinctly longer than wide, apex rounded, in shape of isosceles triangle, with punctuation similar to those on pronotum. Elytron moderately convex, sutural stria deeply impressed in posterior half; each elytron with 10 longitudinal serial punctures, punctures impressed mesally, becoming slightly sulcate posteriorly and laterally, with shallow fine punctures between serial punctures; series 3+4 and 6+7 linked together subposteriorly, other serial punctures reaching end of elytron; lateral four series with punctures larger and deeper than in inner six series; interstices of ground punctures with dense micropunctures in posterior half of elytron, especially in females (Fig. 51).
Legs. Reddish brown, rather short, profemora without pubescence ventrally; protarsomeres pubescent ventrally. Ventral surface of meso- and metafemora without pubescence, with sparse punctures and microsculptures; 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. 24). Aedeagus about 1.7 mm long, ca. 4× as long as wide. Phallobase well developed, almost as long as parameres. Parameres widest in the middle, gradually narrowing towards apex. Median lobe almost as wide as phallobase, apex rounded, reaching only to the middle of parameres, gonopore situated subapically.
Biology (Figs. 65, 69). Living in moist decaying plant material, such as rotten pseudostem of banana trunks, rotten bamboo or rotten figs.
Remarks. Large-sized species (over 5 mm long). Orchymont (1925) described this species to have a distinct shagreen between ground punctures in the posterior half of the elytron. By observing specimens using a scanning electronic microscope, we that this “shagreen” is actujally formed by numerous micropunctures between ground punctures (Fig. 51).
We examined other five large-sized species of Dactylosternum from the Orienal region. Dactylosternum dytiscoides (Fabricius, 1775) can be easily recognized by its reddish head, pronotum and scutellum (Fig. 71). The other four species (D. latum, D. salvazai, D. pseudolatum sp. nov. and D. frater sp. nov.) are all generally black, but can be distinguished from D. hydrophiloides by anterior margin of clypeus without distinct marginal rim (Figs 18, 19) (with marginal rim in D. hydrophiloides); ground punctures with associated microsculpture (Figs. 52–55) (ground punctures simple and interstices with dense micropunctures in D. hydrophiloides, Fig. 51); phallobase shorter than parameres (almost as long as parameres in D. hydrophiloides); and median lobe slender, reaching to subapical part of parameres (very short and broad, reaching only to the midlength of parameres in D. hydrophiloides, Fig. 24).
Distribution. China (Fujian, Guangdong, Hong Kong, Hainan, Guangxi, Guizhou, Taiwan, Yunnan, Xizang) (this paper, Fikáček et al. 2015). New for Xizang, China. Outside China known from the following regions: Oriental: Bhutan, Nepal, India (West Bengal, Andaman Islands), Indonesia (Borneo, Buru, Java, Sulawesi), Malaysia (Malay Peninsula), the Philippines, Singapore, Thailand, Vietnam. Afrotropical (introduced): South Africa. Australian: Australia, Palau Island. Pacific (introduced): Hawaiian Island. Neotropical (introduced): Jamaica (Orchymont 1935, Hansen 1995).
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 275-278, DOI: 10.11646/zootaxa.5091.2.3, http://zenodo.org/record/5843837