Neptosternus wewalkai Balke, Hendrich & Yang, 1997

Zhao, Shuang, Hájek, Jiří, Jia, Fenglong & Pang, Hong, 2012, A taxonomic review of the genus Neptosternus Sharp of China with the description of a new species (Coleoptera: Dytiscidae: Laccophilinae), Zootaxa 3478, pp. 205-212 : 210

Neptosternus wewalkai Balke, Hendrich & Yang, 1997

(Figs. 3–4, 10)

Neptosternus wewalkai Balke, Hendrich & Yang, 1997: 372 (original description; Vietnam).

Material examined. 14 spec., “ China, Guangxi Autonomous Region, Jingxi County, Bangliang, 31.vii.2010, Jianhua Huang leg.” ( NMPC, SYSU).

Notes. Neptosternus wewalkai was described based on the female holotype from northern Vietnam. The specimens from Guangxi are distinctly smaller than the holotype, and their yellow elytral colouration varies among the specimens and differs from that of the holotype. However, no other obvious differences were found, therefore we assign our material to N. wewalkai and provide additional information about its morphology based on both male and female specimens:

Middle-sized, oval species, more or less arched in lateral view. Body distinctly narrowed after elytral midlength.

Measurements (N=8). TL: 2.8–2.9 mm, TL-h: 2.6–2.7 mm, TW: 1.7–1.8 mm.

Colouration. Head dark reddish brown to black, clypeus yellowish brown; pronotum black, sometimes with indistinct transverse reddish brown band medially; elytra black with yellow subbasal band and large apical spot (Fig. 3), in some specimens also with additional more or less distinct one or two median spots (Fig. 4). Venter reddish, procoxae, mesocoxae, mesofemur slightly paler; epipleura yellow anteriorly.

Surface sculpture. Head covered with fine microreticulation composed of shallowly impressed isodiametric meshes. Punctation consist of sparse large punctures between eyes. Head with punctured depression along eyes and another small transverse depression anterolaterally of eyes. Microreticulation of pronotum similar to that of head. Punctation double, small punctures between meshes rather indistinct; large punctures confined predominantly along anterior and posterior margins, several large punctures sparsely distributed on disc. Lateral margin of pronotum medially indistinctly bordered. Microreticulation of elytra composed of shallowly impressed slightly transverse meshes. Punctation of elytra double: densely distributed small punctures between meshes, and coarse large punctures forming four (sutural, discal and two lateral) longitudinal rows; few large punctures distributed sparsely also on disc, especially in basal half. Prosternal process trifurcated, apically pointed. Abdominal ventrites 3–5 with row of sparse setigerous punctures. Abdominal ventrite 5 with one median long and thick seta. Ventral part with fine microreticulation composed of slightly transverse polygonal meshes; punctation fine and dense.

Male. Median lobe of aedeagus in ventral view broadened in middle, broadest in apical third, then abruptly attenuated to acute apex ( Fig. 10 ).

Collection circumstances. Collected at light.

Distribution. Southern China (Guangxi) and northern Vietnam.

Figures

FIGURES 9 – 13. Median lobe of aedeagus in ventral view. 9 — Neptosternus punctatus sp. nov.; 10 — N. wewalkai; 11 — N. hydaticoides; 12 — N. coomani; 13 — N. strnadi. Scale bar = 0.1 mm.