Megarthrus panda, Liu & Cuccodoro, 2021

Liu, Zhiping & Cuccodoro, Giulio, 2021, Megarthrus of China. Part 4. The M. hemipterus complex (Coleoptera, Staphylinidae, Proteininae), with description of a new species from Yunnan Province, ZooKeys 1056, pp. 17-34 : 17

Megarthrus panda sp. nov.

Figs 19-21 , 22-23 , 24-32 , 33-40

Type material.

Holotype (♂): China: Yunnan Prov.: Jizu Shan 25.58N 100.21E, 2500-2700 m, 6-10.vii.1994, leg. V. Kubáñ, in NHMB. Paratypes (20): Same data as holotype, 1 ♂ and 1 ♀ in NHMB, 1 ♂ and 1 ♀ in MHNG; China: Yunnan Prov.: NE Kunming, 25°08'35"N, 102°53'49"E, 2320 m, 13.viii.2014, leg. M. Schülke [CH14-06], mixed forest with alder, oak and pine, litter and mushrooms, sifted, 2 ♂ and 3 ♀ in cSch, 1 ♂ and 1 ♀ in MHNG & 1 ♂ and 1 ♀ in SWUC; NE Kunming, 25°08'40" N, 102°53'48"E, 2290 m, 11.viii.2014, leg. M. Schülke [CH14-05], mixed deciduous forest with scattered pine trees, litter and mushrooms sifted, 1 ♂ in cSch; Dali Aut. Pref. Mão Jiao Shan, E pass, 58 km NE Dali, 25°56'41"N, 100°40'05"E, 2525 m, 4.ix.2009, leg. M. Schülke [CH 09-26] secondary mixed forest, litter, moss & mushrooms, sifted, 1 ♂ and 4 ♀ in cSch & 1 ♀ in MHNG.

Description.

Combined length of head, pronotum and elytra = 1.7-2.1 mm; maximal pronotal width = 0.9-1.3 mm. Body (Figs 19-21 ) predominantly chestnut brown, with pronotum usually slightly paler, frons slightly paler than vertex, and legs slightly paler than elytra. Anterior frontal margin slightly carinate, evenly convex in dorsal view. Antenna as in Fig. 36 . Prothorax as in Figs 22 , 23 .

Male. Protibia fairly straight and evenly expanding from base to apex; adventral side flattened. Mesotrochanter (Fig. 28 ) with about twenty peg-like setae grouped as a field. Mesofemur (Fig. 28 ) slightly arcuate and slightly swollen. Mesotibia (Fig. 27 ) subangulate, bearing peg-like setae arranged in two rows. Metatrochanter and metafemur (Fig. 29 ) markedly swollen; posterior margin of metatrochanter broadly rectangular; posterior margin of metafemur concave in ventral view, forming sharp ridge on half length. Metatibia (Fig. 26 ) swollen, with adventral side flattened and broadly emarginated on apical two-thirds; metatibial peg-like setae grouped as a field on apical quarter with additional peg-like setae arranged in scattered row bordering each side of emargination. Abdominal tergite VIII as in Figs 30 , 31 ; abdominal sternite VIII in Fig. 32 ; hemitergites IX as in Fig. 39 . Aedeagus (Figs 24 , 25 ) with ventral wall strongly narrowed at apical third in ventral view, with ventral outline markedly sinuate to slender apex strongly recurved ventrally in lateral view.

Female. Abdominal tergite VIII as in Figs 37 , 38 . Valvifers as in Figs 34 , 35 . Gonocoxal plate (Figs 34 , 35 ) with lateral portions of dorsobasal margin oblique to median portion truncate, markedly projecting anterad. Dorsal part of genitalia (Fig. 33 ) with arcuate sclerite slightly wider at middle.

Comparisons and diagnostic notes.

Megarthrus dentipes , M. flavolimbatus , M. hemipterus and M. panda sp. nov. are the only members of the genus to have the anterior frontal margin carinate, the antennae bearing short and dense pubescence only on antennomeres 5-11, hemispherical eyes with the highest point above level of the vertex, the lateral sides of pronotum and elytra slightly deplanate, the prohypomera without a marked ridge, and the pubescence on abdominal tergites parallel. Within these species M. panda sp. nov. can be easily distinguished by the shape posterior legs of the males (Figs 26 , 29 ). Its genitalia are also diagnostic, notably in the male by the aedeagal ventral wall strongly sinuate in lateral view (Fig. 25 ), and in the female by the arcuate dorsal genital sclerite slightly wider at middle in combination with the dorsobasal margin of the gonocoxal plate evenly narrowed to its truncate median portion projecting anterad (Fig. 34 ).

Distribution and natural history.

The species is endemic to Yunnan Province (Fig. 41 ), where it was found at elevations ranging from 2290 to 2700 m a. s. l. from July to September by sifting leaf litter with mushrooms in mixed deciduous forests with alder, oak and pine.

Etymology.

Megarthrus panda sp. nov. shares the main body color and the forested mountains of Yunnan Province with its eponymous mammal the small Megarthrus panda , Ailurus fulgens Cuvier, 1825. Noun in apposition.

Figures

Figure 41. Distribution map in China of Megarthrus dentipes Bernhauer, M. flavolimbatus Cameron, M. hemipterus (Illiger) and Megarthrus panda sp. nov. Scale bar: 300 km.

Figures 19 - 21. Megarthrus panda sp. nov.: habitus, male: dorsal 19 ventral 20, and lateral 21 views. Scale bar: 0.5 mm.

Figures 22 - 23. Megarthrus panda sp. nov., prothorax in dorsal 22 and ventral 23 views. Scale bar: 0.2 mm.

Figures 24 - 32. Megarthrus panda sp. nov., aedeagus in ventral 24 and lateral 25 views; metatibiae 26 mesotibiae 27 mesotrochanter and mesofemur 28 metatrochanter and metafemur 29 tergite VIII in lateral 30 and ventral 31 views sternite VIII in ventral view 32. Scale bar: 0.1 mm.

Figures 33 - 40. Megarthrus panda sp. nov., female genital segments, dorsal part in ventral view 33 and ventral part in dorsal 34 and lateral 35 views antenna 36 female tergite VIII in lateral 37 and dorsal 38 views male left hemitergite IX 39 female sternite VIII in ventral view 40. Scale bar: 0.1 mm.