Nigidius distinctus, Parry, 1873

Lin, J. - Z., 2022, A new species of the genus Nigidius MacLeay (Coleoptera: Lucanidae) from the Green Island, Eastern Taiwan, Far Eastern Entomologist 451, pp. 19-28 : 26

Key to the species of the Nigidius distinctus species group from East Asia

1. Canthus with outer margin entirely outside of the eye laterally. Pronotum without a minute central process at posterior carina. Myanmar, China: Yunnan. ( Fig. 22 ) ....................... ......................................................................................................................... N. distinctus

– Bottom of the emargination of the canthus inside of the outer limit of the eye. Pronotum have a minute central process at posterior carina .............................................................. 2

2. Canthus posterior angles more horizontal, with the processes at anterior and posterior angles more subequal in length. Corner lobe of the pronotum is placed more anteriorly than laterally; pronotum distinctly serrate in front. Female genitalia with stylus noticeably stouter and situated at a little prior to the gently rounded distal end. China: Hong Kong, Guangdong, Hainan. ( Fig. 23 ) ............................................................................ N. sinicus

– Canthus with the process at posterior angle much longer than that at anterior angle. Corner lobe of the pronotum is placed more laterally than anteriorly, with a straight, convex or waved inner border on the pronotum. Stylus of female genitalia placed at the inner apex of the hemisternite ............................................................................................................. 3

3. Canthus less developed, with posterior margin more weakly produced. Pronotum with lateral margin distinctly to sinuous in middle. Body relatively shorter and wider. Female genitalia with clearly slender and very sharp stylus. Japan. ( Figs 10–12 , 16–18 , 25, 28 , 32 ) ......................................................................................................................... N. lewisi

– Canthus well developed. Pronotum with lateral weak sinuous in middle ............................ 4

4. Pronotum surface variable with almost impunctate and coarsely punctate areas. Elytra shorter. Female genitalia with strongly hooked and short stylus. Taiwan: main island. ( Figs 6–9 , 19–21 , 26, 29 , 33 ) .................................................................................. N. lohi

– Pronotum surface more uniformly punctate. Elytra distinctly longer and slender. Female genitalia with stylus distinctly longer and situated at triangular distal end. – Canthus with posterior margin very strongly produced outward as a fairly sharply pointed projection. Taiwan: Green Island. ( Fig. 34 ) ............................................................. N. wushuae sp. n.

Figures

Fig 34. Type locality and habitat of Nigidius wushuae sp. n.

Figs 13–23. Habitus of Nigidius spp., dorsal view. 13–15 – N. wushuae sp. n.; 16–18 – N.

Figs 10–12. Nigidius lewisi, syntype. 10 – habitus, dorsal view; 11 – the same, ventral

Figs 24–29. Male (24–26) and female (27–29) genitalia of Nigidius spp. 24, 27 – N.

Figs 30–33. Head and pronotum of Nigidius spp. 30, 31 – N. wushuae sp. n.: 30 – cantus;

Figs 6–9. Nigidius lohi, holotype. 6 – habitus, dorsal view; 7 – the same, ventral view; 8 –