Cybister (Melanectes) danxiaensis, Jiang & Zhao & Mai & Jia & Hendrich, 2023

Jiang, Zhuo-Yin, Zhao, Shuang, Mai, Zu-Qi, Jia, Feng-Long & Hendrich, Lars, 2023, Review of the genus Cybister in China, with description of a new species from Guangdong (Coleoptera: Dytiscidae), Acta Entomologica Musei Nationalis Pragae 63 (1), pp. 75-102 : 93-95

Cybister (Melanectes) danxiaensis sp. nov.

( Figs 14A–E ; 15A–E ; 22B )

Type locality. China, Guangdong Province, Shaoguan, Renhua County, Danxiashan Mt., ca. 25.0244N, 113.7158E.

Type material. HOLOTYPE: J ( SYSU), labelled:“tṭ ṯffl ñȇ / 1941. VIII / Hľ [hw] // CHINA: Guangdong Province / Renhua County /

Danxiashan Mt. / viii.1941, Ping Lin leg. [p] // HOLOTYPE / CYBISTER / danxiaensis sp. nov. / Jiang, Zhao, Mai & Jia det. 2021 [red label, p]”.

Description. Habitus ( Fig. 15A ) elongate oblong oval, with continuous outline, widest in apical third of elytra, moderately convex. Dorsal surface distinctly matt. TL 21.7 mm; TL-h 19.4 mm. MW 11.3 mm.

Colouration. Head black; pronotum black with broad brown sides; elytra blackish brown; appendages black; ventral side blackish brown.

Head moderately broad, ca. 0.6× width of pronotum, trapezoidal. Surface densely covered with fine punctures. A pair of depressions present near anterior margin of clypeus. Anterior margin of clypeus concave. Labium and genae with some punctures near gular suture.Antenna with antennomeres long and slender.

Pronotum transverse (width/length ratio = 2.36), broadest between posterior angles, lateral margins moderately curved, without lateral bead. Punctation double; coarse setigerous puncture row present along anterior margin, with a perpendicular setigerous puncture row laterally that does not reach posterior margin; fine punctures dense throughout whole surface. Centre of disc with a moderately impressed longitudinal line medially.

Elytra with dense large protuberances that are arranged almost in rows; each protuberance with a puncture medially in which is a small granule ( Fig. 14A ). Punctation double; larger punctures sparse between protuberances; finer punctures dense throughout whole surface. Medioapical area of elytra with a field of short, coarse setae ( Fig. 14B ).

Ventral side ( Fig. 15B ). Prosternal process lanceolate, with distinct lateral bead, surface flat, apex pointed ( Fig. 14C ). Lateral parts of metaventrite tongue-shaped, slender, not reaching lateral margins; metacoxal lines distinct, well impressed, nearly parallel medially, divergent anteriorly, along metacoxal lines with a row of punctures ( Fig. 14D ). Lateral part of abdominal ventrites without spot.

Legs. Protarsomeres 1–3 with four rows of adhesive setae on their ventral side, broadly expanded into a palette; claws simple. Mesotibia with setae in a continuous line on posteroapical margin; mesotarsomeres with two separate series of setae present along posteroventral and posterodorsal apical margin; claws simple ( Fig. 14E ). Hindlegs lost.

Male genitalia. Median lobe of aedeagus ʻCʼ- shaped in lateral view, strongly curved, broadest at middle, strongly narrowing in apical fourth, apex rounded ( Fig. 15C ); in ventral view broad at base, apical fourth slender like a tubular spine, apex rounded ( Fig. 15D ). Parameres moderately broad, distinctly curved in apical third, strap-like apically ( Fig. 15E ).

Female. Unknown.

Differential diagnosis. Based on the pronotum and elytra without distinct lateral yellow margins, the new species can be assigned to subgenus Melanectes ( MILLER et al. 2007) . Within the subgenus, the new species is similar to Cybister sugillatus but can easily be recognized by the large punctate protuberances on the elytra and the longer apical slender part of the median lobe of the aedeagus (elytra smooth without punctate protuberances, apical slender part of median lobe of aedeagus shorter in C. sugillatus ).

Etymology. The species is named after the type locality, Danxiashan Mt., Guangdong Province, China; the name is an adjective.

Distribution. So far known only from the type locality in northern Guangdong, China ( Fig. 22B ).

Figures

Fig. 14. Morphological characters of Cybister danxiaensis sp. nov. A – detail of elytral structure; B – Medioapical area of elytra viewed with sutural margin at bottom of picture;C – prosternal process; D – metacoxal lines; E – mesotaromeres. Scale bars: 1.0 mm.

Fig. 15. Cybister danxiaensis sp. nov. (holotype J). A – habitus in dorsal view; B – habitus in ventral view; C – median lobe of aedeagus in lateral view; D – median lobe of aedeagus in ventral view; E – paramere. Scale bars: 5.0 mm (A, B), 1.0 mm (C–E).

Fig. 22. Map of distribution of Cybister in China.