Lucanus gradivus n.sp. from Vietnam is described. It belongs to the large of L. fortunei Saunders, 1854 species group and is closely related to L. fujitai Katsura & Giang 2002. Lucanus gradivus differs mainly through the stronger and differently denticulated mandibles, larger and more pronounced posterolateral corners of the cephalic lobes, and the aedeagus, with longer flagellum, shorter and thinner median lobe, and longer apically curved parameres.
Lucanidae, Lucanus, new species, Vietnam