Dactylosternum pseudolatum Mai et Jia 2022, sp. nov.
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 pseudolatum

description: Dactylosternum pseudolatum Mai et Jia, sp. nov.
(Figs. 7, 19, 27–29, 52, 56, 60)
Type material examined. HOLOTYPE: male (SYSU), Guangdong, Shaoguan Prefecture, Chebaling Nature Reserve, 23°14′46″N 113°33′56″E, 496 m, 28–29.V.2017, Jia, Wang & Leung leg. PARATYPE: 1 male (IRSNB) “ Laos / 28.3.1918 / Vitalis // male symbol // co- / type // Para- / type // A. d´Orchymont det. / Dactylosternum 1922 / Vitalisi d´Orchymont ”; Fujian: 1 male (SYSU), Nanping City, Mangdangshan, 26°41′51″N, 118°07′00″E, mixed forest, leaf litter shifted, 400 m, 10.XI.2015, Yan & Tang leg.; Guangdong, 7 spec. (SYSU), same information as the holotype; 1 male, Shaoguan Prefecture, Chebaling Nature Reserve, 23.7038°N 114.1914°E, 399 m, 27.V– 1.VI.2019, XingminWang.; Hainan, 3 spec. (SYSU), Bawangling, Dongwu District, 8.V.2011, Zhao leg.; 1 spec. (SYSU), Limushan, Limu Temple, 5.V.2011, Zhao leg.; Jiangxi, 15 spec. (SYSU), Jinggangshan Prefecture, Xiangzhou, 26.IV.2011, Jia leg.; 4 spec. (KMNH), Jinggangshan Prefecture, Xiangzhou, 26.IV.2011, Jia leg.; 4 spec. (NMPC), Jinggangshan Prefecture, Xiangzhou, 26.IV.2011, Jia leg.; Yunnan, 6 spec. (SYSU), Baoshan Prefecture, Baihualing, 25°10′N 98°16′E, 1516 m, 18.IV.2015, Lin & Tang leg.; 1 spec. (SYSU), Xishuangbanna, Wangtianshu, 23. V.2016, Lu Qiu leg.; 2 spec. (SYSU), Cheli, 600 m, 22.IV.1957, Hong leg.; 2 spec. (SYSU), Xishuangbanna, 580 m, 22.IV.1957, Pu leg.; 1 spec. (HBUM), Laiyanghe, Xinzhai village, 22.631°N 101.132°E, 1487 m, 21.V.2011, Song leg.
Diagnosis. Length 5.9–7.2 mm. Body oval, anterior half of elytra slightly parallel-sided (fig. 7), moderately convex. Dorsal black, surface with dense and fine punctures. Anterior margin of clypeus without marginal rim (Fig. 19). Antenna yellowish brown, club compact. Elytron with sutural stria and 10 distinct rows of serial punctures, all nearly reaching elytral base, ground punctures attached with one/two short transverse microsculptures.Anteromedial portion of metaventral process with a short transverse groove (Fig. 56). Posterior margin of ventrite 5 with distinct marginal bead and a stria behind the marginal bead (Fig. 60). Aedeagus (Figs. 27–29): Phallobase shorter than parameres. Parameres distinctly sinuate on outer margin, and strongly curved subapically. Median lobe widest in the middle, a little shorter than parameres; ventral plate triangular, strongly pointed at apex, gonopore situated at apex of ventral plate (Figs. 27c, 28c).
Description. Total length 5.9–7.2 mm; maximum width 3.6–4.2 mm; body oval, moderately convex.
Coloration. Dorsal black, with lateral margin of elytron reddish brown (Fig. 7). Maxillary palps and antenna yellowish brown. Ventral black to reddish brown, legs reddish brown.
Head. Clypeus weakly convex, surface with dense and fine punctures, anterior portion with denser punctures. Interstices between punctures smooth. Anterior margin of clypeus without marginal rim (Fig. 19). Frons with punctures sparser than those on clypeus. Eyes of moderate size, separated by ca. 6× as wide as one eye, distinctly emarginate anteriorly in lateral view, smooth medially. Maxilla with glabrous basistipes. Mentum transverse, glabrous, 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 longest. Antennal scapus longest, rather thick, ca. 7.5× as long as pedicellus, antennomere 3 thin and a little shorter than pedicellus, antennomeres 4 and 5 almost equal in length, slightly widening distally, 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, with punctures sparser than those on vertex, interstices between punctures smooth; posterior margin slightly arcuate. Prosternum strongly tectiform, with median carina and a distinct tooth anteromedially.
Meso- and metathorax. Scutellum distinctly longer than wide, apex rounded, in shape of isosceles triangle, with punctation similar to those on pronotum. Elytron moderately convex, sutural stria deeply impressed in posterior half; each elytron with 10 longitudinal serial punctures, deeply impressed in posterior half, intervals with fine ground punctures, each puncture with one/two short transverse lines especially in posterior half (Fig. 52); series 3+4 and 6+7 linked together subposteriorly, others serial punctures reaching end of elytron; lateral four series with punctures larger and deeper than those in the inner six series. Anteromedial portion of metaventral process with a short transverse groove (Fig. 56).
Legs. Reddish brown, rather short. Procoxae globular, pubescent; 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. Posteromedial portion of ventrite 5 without pubescence, with fine punctures, posterior margin of ventrite 5 rounded, with a stria in front of the marginal bead (Fig. 60).
Male genitalia (Figs. 27–29). Aedeagus about 1.1 mm long, ca. 2.2× as long as wide. Phallobase shorter than parameres, with short manubrium and rounded posteriorly. Parameres strongly curved inwards apically, pointed at apex, sinuate on outer margin. Median lobe ca. 0.94× as long as parameres, widest in the middle, gradually narrowing towards apex; ventral plate triangular, widest basally, tapering towards apex, strongly pointed at apex (Figs. 27c, 28c). Gonopore triangular, situated at apex of ventral plate, reaching ca. distal 0.8 of median lobe.
Etymology. This species name is a combination of the Latin pseudo -, false, and the species name of Dactylosternum latum. The name refers to the fact that this species is quite similar to D. latum in morphology characters.
Biology. Living in moist plant material, such as decaying pseudostem of banana trunks and in leaf litter.
Remarks. We examined two specimens of the type series of Dactylosternum vitalisi (the holotype and a paratype from Laos), in which we found several morphological differences. The holotype differs from the paratype in the morphology of the anterior part of the metaventral elevation, the mesoventral elevation, especially in the shapes of the aedeagus (compare Figs 29 and 36). This indicates that the holotype and paratype of D. vitalisi each represent a different species. The paratype of D. vitalisi is possibly represent an undescribed species. This new species is similar to D. salvazai Orchymont, D. latum (Sharp, 1873) and D. frater sp. nov. in both habitus and aedeagus morphology. It can be distinguished from the latter three species by dorsal surface with rather densely arranged fine punctures, less shiny (with sparser punctures on the dorsal surface and shiny in the latter three species). It can be distinguished from D. salvazai by anteromedial portion of metaventral process with a short transverse groove (Fig. 56) (anteromedial portion of metaventrite, behind metaventral process with a Λ-shape divergent ridge in D. salvazai, Fig. 57), each elytral ground puncture with one/two short transverse line especially in the posterior half of elytra (Fig. 52) (each puncture with a K/H-shape microsculpture in D. salvazai, Fig. 53), posteromedial portion of ventrite 5 with fine punctures (Fig. 60) (with mesh-like microsculpture instead of puncture in D. salvazai, Fig. 61), parameres distinctly sinuate on outer margin and more curved on lateral margin subapically (Figs. 27–29) (not sinuate and less curved on lateral margin subapically in D. salvazai, Figs. 25a,b) and ventral plate of the median lobe strongly pointed apically (Figs 27c, 28c) (rounded at apex in D. salvazai, Fig. 25c). The new species differs from D. latum and D. frater by anteromedial portion of metaventral process with a short transverse groove (Fig. 56) (with a strongly impressed pit in D. latum (Fig. 58) or slightly impressed pit in D. frater (Fig. 59)), posterior margin of ventrite 5 with distinct marginal bead and a stria behind the marginal bead (Fig. 60) (with fine marginal bead and without stria in D. latum and D. frater; Figs. 62–63).
Variability. Outer margin of parameres of the specimen from Hainan Island not so sinuated in apical twothirds as in specimens from other areas (Figs 28a,b). In this aspect, the aedeagus of the Hainan specimens is almost the same as that of the paratype of D. vitalisi from Laos. The latter specimens also corresponds with the Chinese specimens of D. pseudolatum in external morphology. We hence treat the paratype of D. vitalisi as a paratype of D. pseudolatum herein.
Distribution. China (Guangdong, Jiangxi, Fujian, Hainan, Yunnan), Laos.
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 289-292, DOI: 10.11646/zootaxa.5091.2.3, http://zenodo.org/record/5843837