About Sinodendron rugosum Mannerheim, 1843
This species, Sinodendron rugosum Mannerheim, 1843, displays sexual dimorphism in its adults, which is a common trait among Lucanidae. Adults also have unopposable clubbed antennae. Both sexes of this species are black, measure between 11–18 millimetres (0.43–0.71 in) in length, and have small mandibles. The pronotum and elytra are covered in many small pits, which gives the insect an overall rugose texture. Males have a much narrower head than the pronotum, plus a short, median rhinoceros-like horn. Females either lack a horn entirely, or only have a small median tubercle. Sinodendron rugosum occurs in moist woodlands ranging from British Columbia to California. Adult individuals are commonly found on the ground between spring and early summer.
