A new species of the stag-beetle genus Aegus MacLeay, 1819 (Coleoptera: Lucanidae) from Northern Vietnam

A new lucanid species, Aegus robustus sp. nov., is described from Northern Vietnam (Ha Giang and Yen Bai provinces) based on 16 male specimens with diverse body sizes. This new species resembles Aegus imitator Nagel, 1941, which is known from mainland China in terms of general external morphology, but it is distinguishable by several characteristics, including the mandibular teeth and abdominal segments VIII and IX. A checklist of all named species of Aegus from Vietnam is provided, with 15 species and one subspecies.