Meligethes yak, Liu, Meike, Yang, Xingke, Huang, Min, Jelínek, Josef & Audisio, Paolo, 2016

Liu, Meike, Yang, Xingke, Huang, Min, Jelínek, Josef & Audisio, Paolo, 2016, Four new species of Meligethes Stephens from China and additional data on other species of the genus (Coleoptera: Nitidulidae: Meligethinae), Zootaxa 4121 (2), pp. 101-116 : 106-108

Meligethes (s.str.) yak sp. nov.

( Figs. 5–6 , 28–29)

Diagnosis. Meligethes yak sp. nov. is a member of the M. binotatus-auripilis group ( Audisio et al. 2015), where it appears to be related to some species of the large M. binotatus complex as defined by Audisio et al. (2015). Among members of this complex, which are easily distinguished by the different shape of male and female genitalia, the new species could be sister to M. nivalis Audisio, Sabatelli & Jelínek, 2015 from SW China (Tibet, Chongqing); these two species share, in fact, not only the typical chromatic characters of members of the M. binotatus complex [blackish to brown elytral coloration combined with yellowish to orange legs and antennae (with darker antennal club) and orange or yellowish pronotum with darker discal spots], but also the peculiar shape of the median lobe of the aedeagus, long, large, parallel-sided and abruptly narrowed distad, bearing along its distal lateral edges a series of short but distinct sensillum-like setae ( Figs. 5–6, 7–8 ). The new species can be differentiated by the shorter elytra, the peculiarly small-sized tegmen with broadly rounded apices of paramera, separated by a peculiarly narrow and deep excision, and the truncately rounded distal apex of the peculiarly large median lobe of the aedeagus ( Figs. 5–6 ). Female genitalia of the new species are unknown.

Description (male holotype). Size: Length 2.6 mm, width 1.7 mm.

Body color and pubescence: External habitus and coloration as figured (Figs. 28–29; the type specimen is slightly teneral); dorsal body surface yellowish-orange on pronotum, with darker (brown) spots on pronotal discal area, and slightly darker (orange-brown) head and elytra; ventral surface mostly orange-brown (Fig. 29). Antennae yellowish, with slightly darker (pale brown) antennal club; legs entirely yellowish (Fig. 29). Pubescence on pronotum with peculiarly long and recumbent setae, silvery-golden and dense, partly obscuring the dorsal surface at least in posterior half and towards sides, shorter and much darker (nut brown) on part of pronotal disc (Fig. 28); elytral pubescence silvery-golden and dense, shorter and finer than on pronotum and usually uniformly disposed, never obscuring dorsal surface.

Dorsal habitus: body moderately convex, peculiarly wide and relatively short (Fig. 28). Ratio LPR1/LELY = 0.65; ratio WPR1/LPR1 = 1.90; ratio WPR2/LPR1 = 1.92; ratio WPR2/WPR1 = 1.01; ratio LELY/WELY = 0.75; ratio WPR1/WPRA = 1.73; ratio WPR1/WELY = 0.89; ratio WPR2/WELY = 0.90.

Anterior margin of clypeus distinctly and widely arcuately emarginate; pronotum with blunt but distinct posterior angles (Figs. 28–29), distinctly projecting backwards. Frons and pronotum with punctures nearly of same size as eye facets, separated by <1 diameter. Elytral punctures markedly finer, shallower and more dense than those on pronotum, smaller in size than eye facet, oval, separated by <1 diameter, with distinct traces of fine transversal strigosity, more marked around scutellum. Interspaces between punctures on head and pronotum more or less shining; interspaces between elytral punctures more distinctly reticulated and much duller. Pygidium with rather dense flatly granular punctures, its apex scarcely obtusangulate, not prolonged into a distinct process (Fig. 29).

Ventral habitus (Fig. 29): Prosternal process subparallel-sided, narrow, acute distad. Male metaventrite exhibiting a marked and deep mediolongitudinal impression, widened behind its midlength, area lateral to this impression markedly convex, densely punctate, shining, at sides duller, without tufts of erect setae.

Appendages: antennae (Fig. 29) rather long and slender, exhibiting ratio ANLE/HWEA = 1.09; ratio CLLE/ W10J = 1.42; ratio L03J/W03J ≈ 3.30; ratio L03J/L02J = 1.35; ratio L03J/L04J =1.45. Protarsal plates (Fig. 29) moderately wide, ratio WFTA/LFTA = 0.33; protibiae with minute rather sharp teeth on apical third of outer margin, exhibiting a ratio LETI/WITI ≈ 3.2. Male metafemora normally developed, when extended protruding outwards beyond elytral sides as in most other known species of the genus, the ratio between the protrusion of distal apex of male metafemora beyond elytral lateral edge being ≈ 0.22× of the head width (HWEA) (Fig. 29); this character state is combined with not sinuate, simply arcuated male meso- and metatibiae along inner edge. Metatibiae only moderately elongate, ratio WPTI/LPTI = 0.32.

Male genitalia: shape of both tegmen and median lobe of the aedeagus as figured ( Figs. 5–6 ), characterized by large, long and parallel-sided median lobe of the aedeagus, abruptly narrowed distad, with truncately rounded apex, ratio LEAE/WIAE = 2.60. Lateral and dorso-lateral edges of the median lobe of the aedeagus in dorsal view with a series of short but quite distinct, sensillum-like setae ( Fig. 6 ). Tegmen moderately wide, small, much shorter than the median lobe, parallel-sided, medial distal excision rather deep and peculiarly narrow (ratio DTIN/LETE ≈ 0.43), inner margin without marked projection, paramera obtusely and widely rounded distad ( Fig. 5 ); ratio LETE/ WITE = 1.36. Main sclerites of internal sac (endophallus) not available in the examined specimen.

Female: unknown.

Type material. Male holotype: China: Sichuan Province, Barkam County, Maerkang [ca. 31.56 ° N, 102.09 ° E], 2500 m a.s.l., 20.viii.1983, Wang Ruiqi lgt., 1 ♂ ( IZAS).

Distribution. EPA: SCH.

Meligethes yak sp. nov. is only known from a single locality in central SW China (middle-high altitude areas of the NW Sichuan Province).

Chorotype. Central-SW Chinese.

Host-plants. Unknown. Probably associated with mountain Rosaceae , perhaps Rosa or allied genera.

Habitat. Scrub in high altitude plains; collected at 2500 m.

Phenology. VIII.

DNA data. Not available.

Name derivation. Name derived from the common name of the Yak ( Bos grunniens Linnaeus, 1766 ), the widespread long-haired representative of the family Bovidae characteristic of the Tibetan Plateau.

Taxonomic remarks. Meligethes yak sp. nov. is member of a large complex of related species mainly distributed in central and southern China, easily distinguishable from each other by the different shape of male genitalia (see Diagnosis above). It could be geographically vicariant of the closely related M. nivalis , which is distributed in E Tibet and W Chongqing.

Figures

FIGURES 1 – 8. Male genitalia of Meligethes spp. 1 – 2: M. macrofemoratus sp. nov. (male paratype from China, Ningxia Hui Autonomous Region, Xixia Valley). 3 – 4: M. clinei Audisio, Sabatelli & Jelínek, 2015 (male holotype from China, Yunnan, Yulong Mts). 5 – 6: M. yak sp. nov. (male holotype from China, Sichuan, Maerkang). 7 – 8: M. nivalis Audisio, Sabatelli & Jelínek, 2015 (male paratype from China, Tibet, Yang Jing). Scale bar = 0.2 mm (Figs. 1 – 8).