Platynectes pangu, Jiang & Zhao & Jia & Šťastný, 2023

Jiang, Zhuo-Yin, Zhao, Shuang, Jia, Feng-Long & Šťastný, Jaroslav, 2023, Two new species of Platynectes Régimbart, 1879 from China with notes on other Chinese members of the genus, including a key to species (Coleoptera: Dytiscidae: Agabinae), Zootaxa 5227 (4), pp. 401-425 : 404-406

Platynectes pangu sp. nov.

( Figs 1B, E–F , 9D , 12B )

Type locality. China, Yunnan Province, Lvchun County, Huanglianshan Reservoir , ca. 22.8898N, 102.2952E, 1720 m .

Type material. Holotype ♂ ( SYSU), labelled: “ ř南ḂữƀhĦḖƜṁw / 22.8898N,102.2952E / 1717.3 m, 2021.IV.30 / ƃfflDz，KflM，RDZƛ，ĦÍṮ [p] // CHINA: Yunnan Province / Lvchun County / Huanglianshan Reservoir / 22.8898N, 102.2952E / 1717.3 m, 30.iv.2021 / Z. Jiang, Z. Yang, Z. Mai & / B. Huang leg. [p] // HOLOTYPE / PLATYNECTES / pangu sp. nov. / Jiang, Jia & Šťastný det. 2022 [red label, p]” . Paratypes: 18 ♂, 5 ♀, same label data as holotype and with respective paratype labels ( SYSU) .

Description of male holotype. Habitus ( Fig. 1B ) oblong-oval, with continuous outline, broadest before middle of elytral length, moderately convex. Dorsal surface slightly matt due to distinct reticulation.

Colouration. Head orange-brown, with black triangular spots on frons between eyes, antero-lateral part to eyes and vertex reddish-brown; pronotum black with anterior angles and lateral margins orange-brown, anterior margin and transverse medial band reddish-brown; elytra black with yellow transverse basal fascia and with eight longitudinal vittae; appendages reddish-brown; ventral side black with reddish-brown spot on each side of abdominal ventrites II–IV.

Head. Moderately broad, ca. 0.65× width of pronotum. Anterior margin of clypeus semicircular, with pair of sublateral foveae. Antenna with antennomeres long and slender. Eyes emarginate anterolaterally. Punctation double; several coarse setigerous punctures present in fronto-clypeal grooves and in depressions along inner margin of eyes; fine punctures distributed sparsely and irregularly on head surface, mainly at intersections of reticulation. Reticulation deeply impressed consisting of heterogeneous, somewhat elongate, polygonal meshes; most meshes closed, usually with several micropunctures inside.

Pronotum. Transverse (width/length ratio = 3.5), broadest between posterior angles. Sides moderately curved, with distinct bead. Anterior margin nearly straight, posterior margin slightly sinuate. Punctation double, similar to that of head; rows of coarse setigerous punctures present along anterior margin and lateral parts of basal margin; fine punctures distributed irregularly on pronotal surface, mainly at intersections of meshes. Reticulation similar to that of head, on disc meshes larger and less impressed, sometimes not closed, near sides becoming much smaller and more deeply impressed. Centre of disc with small indistinct longitudinal furrow.

Elytra. Base of elytra as broad as pronotal base; lateral margins of elytra moderately curved. Yellow transverse fascia presents at base of elytra, interrupted only sublaterally. Eight yellow longitudinal vittae present on each elytron: vitta 1 almost continuous, vittae 2–7 formed by series of dots, vitta 8 continuous, vitta 5 bifurcate anteriorly; all vittae beginning at transverse basal fascia and ending at apex. Punctation double; coarse setigerous punctures present along vittae 1, 3, 5, 7 and lateral margins of elytra; fine punctures distributed irregularly over elytral surface, mainly at intersections of reticulation. Reticulation well impressed, similar to that of head and pronotum, meshes usually with several micropunctures inside, sometimes not closed.

Legs. Meso- and metafemora with tuft of spiniform setae along ventral margin of anteroapical angle. Pro- and mesotibia broadened, club shaped, densely punctured with spinigerous punctures over ventral surface. Metatibia with two lines of coarse spinigerous punctures on ventral surface. Pro- and mesotarsomeres 1–3 moderately broadened, with adhesive setae on ventral side; claws simple. Metatarsal claws subequal; anterior claw slightly shorter than posterior one. Surface of legs with distinct reticulation consisting of elongate meshes.

Ventral side. Anterior margin of prosternum sinuate anteriorly, obtusely keeled medially. Prosternal process shortly lanceolate, in cross-section convex, with distinct lateral bead in basal half, apex pointed; surface with irregular sparse double punctation. Medial part of metaventrite without microsculpture, shiny, with sparse fine punctation; lateral parts of metaventrite (“metasternal wings”) tongue-shaped, slender, reaching lateral margins. Metacoxal lines distinct, well impressed, subparallel anteriorly, divergent posteriorly. Metacoxal plates covered with shallow transverse wrinkles; reticulation consisting of polygonal meshes, punctation consisting of sparse fine punctures. Conjoint posterior margin of metacoxal processes slightly concave. Abdominal reticulation consisting of elongate polygonal meshes, longitudinal on ventrites I, oblique on ventrite II and transverse on ventrites III–V; ventrites III–V additionally with numerous fine transverse wrinkles medially. Punctation double; ventrites III–V with setigerous punctures arranged sparsely in transverse line in medial part and with one coarser setigerous puncture presents in the middle; fine punctures distributed sparsely and irregularly on ventrite surface. Abdominal ventrite VI with sublateral rugose area comprising more than 10 deep longitudinal grooves on each side; reticulation present only baso-laterally; punctation double, coarse setigerous punctures present along posterior margin, fine punctures distributed densely on middle part.

Male genitalia. Median lobe of aedeagus in lateral view strongly curved; strongly broadened in apical fifth, with distinct setae subapically along both ventral and dorsal margins; apex rounded, bevelled on both dorsal and ventral sides ( Fig. 1E ). Parameres slender, with dense setae dorsally, with distinct subbasal tooth on ventral side ( Fig. 1F ).

Female. Identical to male in habitus. Meshes of dorsal surface reticulation more deeply impressed and longitudinally stretched; in some specimens reticulation consists of extremely dense meshes, all meshes closed, elongate mainly on elytra; surface appearing more matt. Abdominal ventrite VI without deep longitudinal grooves sublaterally. Pro- and mesotibia less broadened; pro- and mesotarsomeres not broadened, without adhesive setae ventrally.

Variability. All specimens of the type series are rather uniform, being variable in body size. Ventrite II sometimes without reddish-brown spot on each side.

Measurements. TL: 7.3–8.2 mm (mean value: 7.8 ± 0.1 mm); holotype: 7.8 mm. TL-h: 6.6–7.5 mm (mean value: 7.1 ± 0.1 mm); holotype: 7.2 mm. MW: 4.2–4.8 mm (mean value: 4.5 ± 0.1 mm); holotype: 4.6 mm.

Differential diagnosis. The new species can be easily distinguished from other Chinese Platynectes by its large size. In terms of habitus, P. pangu sp. nov. is similar to another large species P. njai Brancucci, 2008 from Laos; however the shape of median lobe is distinctive: in both species, strongly broadened in apical fifth, but with apex widely rounded (see Brancucci 2008, Figs 2–3 ) in P. njai and rounded but bevelled on both dorsal and ventral sides in P. pangu sp. nov..

Collection details. Except for one specimen collected by light trap, all other type specimens were collected in a puddle on the bottom of spillway of the Huanglianshan reservoir ( Fig. 9D ).

Etymology. The species name “ pangu ” refers to a giant in ancient Chinese mythology, representing the large size of the species of subgenus Gueorguievtes Vazirani, 1976 . The species name is a noun standing in apposition.

Distribution. So far known only from the type locality in Huanglianshan Mt., southern Yunnan, China ( Fig. 12B ).

Notes. Brancucci (2008) described a large-sized species P. njai from Laos. He was pretty sure that the two large female specimens from Yunnan (Naturhistorisches Museum Wien) cited by Nilsson (1998) were not conspecific with P. njai . According to the information provided by Nilsson (1998) and Šťastný (2003), these two females probably belong to P. pangu sp. nov.

Figures

FIGURE 1. Habitus and male genitalia of new species. (A, C–D) P. maizuqii sp. nov. (holotype ♂; Danxiashan, Guangdong); (B, E–F) P. pangu sp. nov. (holotype ♂; Huanglianshan, Yunnan). (A, B) habitus in dorsal view; (C, E) median lobe in lateral view; (D, F) paramere. Scale bar = 2.0 mm (A, B); Scale bars = 0.5 mm (C–F).

FIGURE 2. Habitus of Platynectes species. (A) P. babai Satô (♂; Kaohsiung, Taiwan); (B) P. davidorum Hájek et al. (♂; Yaowangshan, Zhejiang); (C) P. dissimilis (Sharp) (♂; Dinghushan, Guangdong); (D) P. dissimilis (Sharp) (♂; Yunhe Village, Hunan). Scale bar = 2.0 mm.

FIGURE 3. Habitus of Platynectes species. (A) P. dissimilis (Sharp) (♂; Gutianshan, Zhejiang); (B) P. gemellatus Šťastný (♂; Nanling, Guangdong); (C) P. gemellatus Šťastný (♂; Gutianshan, Zhejiang); (D) P. hainanensis Nilsson (♂; Limushan, Hainan). Scale bar = 2.0 mm.

FIGURE 9. Habitat of Platynectes species. (A) Limushan, Hainan (P. hainanensis); (B) Pianma, Yunnan (P. kashmiranus lemberki); (C) Lvchun, Yunnan (P. major); (D) Huanglianshan, Yunnan (P. pangu sp. nov.).

FIGURE 12. Maps of distribution of Platynectes species in China. (A) P. kashmiranus lemberki, P. maizuqii sp. nov., P. major and P. mazzoldii; (B) P. nanlingensis, P. pangu sp. nov. and P. rihai.