Chaetarthria chenjuni Jia & Yang, 2020

Jia, Fenglong, Yang, Zhenming, Jiang, Lu, Chen, Kai & Jiang, Shujiao, 2020, Chaetarthria chenjuni Jia & Yang, sp. nov. (Coleoptera: Hydrophilidae), a new species from China and additional faunistic records, Zoological Systematics 45 (2), pp. 146-149 : 147-149

Chaetarthria chenjuni Jia & Yang , sp. nov. ( Figs 1–7 )

Type material. Holotype. male ( SYSU), China, Hainan, Wuzhishan Mt., Guanshandian , 18˚53´N, 109˚41´E, elev. 650 m, 21.IV.2012, Yin Ziwei leg. Paratypes (3 spec. IZCAS; 2 spec. NMPC; 2 spec. SHNU; 6 spec. SYSU) . 5 spec. same data as holotype ; 1 male, 1 female, China, Hainan, Lingshui County, Diaoluoshan Mt., Winding Road , 18˚42´N, 109˚52´E, elev. 600–1000 m, 28.IV.2012, Peng & Dai leg. ; 2 females ( IZCAS: IOZ(E)20022538, IOZ(E)20022533), China, Guangxi, Napo, Defu , elev. 1440 m, 3.IV.1998, Wenzhu Li leg. (transcribed from Chinese) ; 1 female ( IZCAS: IOZ(E)20022536), locality as above, elev. 1300 m, 14.VIII.1998, Tongli He leg. (transcribed from Chinese) ; 3 females, China, Guangdong, Shenzhen, Dapeng Peninsula, Getian Village , 22.48157°N, 114.62643°E, 2.VIII.2019, Jia & Mai leg. (transcribed from Chinese) .

Diagnosis. This new species may be close to C. indica d'Orchymont, 1920 . It can be distinguished from C. indica by its labrum black, elytra uniformly black, maxillary palps piceous, ventral surface black, legs black with tarsomeres dark brown, elytra with distinct punctures as well as the systematic punctures, an arrangement otherwise only known from C. saundersi d'Orchymont in the Oriental Region; aedeagus with median lobe broadly rounded apically, without a flagellum arising out of the middle of anterior margin, gonopore oval ( Fig. 7 ).

General description. Labrum same colour as clypeus, maxillary palps uniformly dark reddish brown, pronotum with posterior angles dark brown, only slightly lighter than disc, elytra uniformly black. Ventral surface black; legs black, with tarsomeres dark brown. Head and pronotum without punctures. Pronotum without distinct anterior angles, posterior angles acute. Elytra with 4 distinct regular series of punctures, between regular series of punctures with 2 distinct irregular series of punctures, lightly finer than systematic punctures, lateral portion with irregular punctures, coarser than those on disc. Aedeagus with phallobase ca. 1.6× as long as parameres, median lobe broadly rounded apically, without a flagellum, gonopore situated apically.

Description. Size and Form. 2.4–2.6 mm. Broadly oval, strongly convex ( Fig. 1 ). Elytra slightly longer than wide. Colour. Dorsum black. Labrum same colour as clypeus or slightly lighter, without lighter anterior margin. Maxillary palps uniformly dark reddish brown. Pronotum with posterior angles dark brown ( Jia et al., 2018: fig. 3a), only slightly lighter than disc. Elytra uniformly black ( Figs 1, 3 ). Ventral surface black. Mentum dark brown. Legs black with slightly lighter tarsomeres; epipleura dark brown.

Head. Ground punctation on labrum, clypeus and frons undetectable ( Fig. 4 ). Systematic punctures on labrum, frons and clypeus very fine but detectable. Labrum not emarginate anteriorly. Eyes small, slightly protruding, separated by ca. 5.5 × width of one eye. Maxillary palps about a half as long as width of head, apical palpomere almost symmetrical and longer than penultimate ( Jia et al., 2018: fig. 3d). Labial palps about one-third as long as width of mentum, apical palpomere conical, shorter than 2nd, 2nd palpomere with numerous long setae on inner and outer face. Antennae 8-segmented, scape almost as long as following antennomeres combined, club loosely segmented. Mentum ( Jia et al., 2018: fig. 3d) longer than wide, quadrate, entire anteriorly; with very fine and scattered punctures anteriorly, not punctate medially.

Thorax. Pronotum shinning, without distinct anterior angles, lateral margin of anterolateral angle dilated, posterior angles acute ( Fig. 6 ); lateral stria present along entire lateral margin, terminating posteriorly at hind angle. Pronotal ground punctation undetectable, systematic punctures very fine but detectable. Elytra smooth and shining, with 4 distinct regular series of punctures ( Fig. 5 ) between regular series of punctures with a few irregular series of punctures ( Fig. 3 ), lateral portion with irregular punctures that are coarser than those on disc. Sutural stria reaching half of elytral length ( Jia et al., 2018: fig. 3c), no series of punctures before sutural stria. Prosternum extremely short, only slightly convex, not carinate. Mesosternum glabrous, slightly concave, with a median, transverse and lightly arcuate ridge at level of anterior mesocoxal margin. Metasternum slightly raised, a little more convex and sparsely pubescent medially. Metepisterna about 4.3× as long as wide, more densely pubescent than metasternum, almost parallel sided except posteriorly, where inner margin bends smoothly towards outer margin. Procoxae densely pubescent, meso- and metacoxae glabrous. Femora with sharply defined tibial grooves on inner face; Femora stout. Pro- and meso-femora densely pubescent except on apical extremity; anterior half of metafemora densely pubescent, posterior half glabrous with some coarse punctures ( Jia et al., 2018: fig. 3b), posterodorsal margin densely pubescent. Tibiae slender, hardly flattened. Tarsi with 5 tarsomeres, first metatarsomere shorter than second.

Abdomen. Ventrites 1–2 with a large cavity on each side, filled with a hyaline mass supported and covered by a fringe of long stiff yellow setae rising from anterior margin of basal ventrite ( Fig. 2 ); first two ventrites carinate medially.

Aedeagus. Aedeagus with phallobase ca. 1.6× as long as parameres; parameres narrowly rounded apically; median lobe distinctly broader than parameres medially, broadly rounded apically, without a flagellum, gonopore situated apically ( Fig. 7 ).

Etymology. The species is named after Dr. Jun Chen, a specialist of mites from Institute of Zoology, Chinese Academy of Sciences, Beijing, China, who kindly invited the senior author to examine the specimens in IZCAS.

Distribution. China (Hainan, Guangxi, Guangdong).

Figures

Figures 1–7. Chaetarthria chenjuni Jia & Yang, sp. nov. 1. Habitus, dorsal view. 2. Habitus, ventral view. 3. Posterior half of elytra. 4. Labrum and clypeus. 5. Pronotal punctures of disc. 6. Pronotum, right portion. 7. Aedeagus. Scale bars: 1–3=0.5mm; 4=100μm; 5=50μm; 6=200μm; 7 =0.1mm.