Nigidius, MacLeay, 1819

Paulsen, M. J., 2018, Revision of the obesus species group of the stag beetle genus Nigidius MacLeay (Coleoptera: Lucanidae: Lucaninae: Figulini), Insecta Mundi 2018 (624), pp. 1-13 : 6-7

Key to Nigidius species in the obesus group

1. Pronotal disc each side of me dian sulcus with small but deep punctures, thus surface appearing entirely punctate ( Fig. 8 ); Sumatra .............................. N. helleri Boileau

– Pronotal disc each side of median sulcus with minute, shallow punctures, thus appearing nearly impunctate, contrasting with adjacent groups of coarse punctures ( Fig. 9 ); not from Sumatra ................................................................... 2

2. Elytral intervals almost impunctate medially, appearing more carinate (intervals with punctures only lateral, adjacent to striae); peninsular Malaysia................. N. obesus Parry

– Elytral intervals punctate medially thus appearing less strongly carinate (intervals irregularly punctate); not from peninsular Malaysia......................................... 3

3. Male genitalia with flagellum sinuous, with small lobe near apex ( Fig. 11 ); Southeast Asia...................................................... N. dawnae Gravely

– Male genitalia with flagellum overall straight, with large lateral lobe distant from apex ( Fig. 12 ); Borneo.............................................. N. gravelyi Paulsen , n. sp.

Figures

Figures 8–9. Pronotal punctation of obesus group species. 8) Surface more uniformly punctate, N. helleri. 9) Surface variable with almost impunctate and coarsely punctate areas, N. gravelyi Paulsen, n. sp.

Figures 10–13. Male genitalia of obesus group species. 10) N. obesus. 11) N. dawnae, arrow indicates small apical lobe. 12) N. gravelyi Paulsen, n. sp. 13) N. helleri, arrow indicates large lateral lobe.