Notes on the genus Onychargia Selys, 1865 (Odonata: Zygoptera: Platycnemididae) with description of O. hungeri sp. nov. from southern Vietnam

This study updates the distribution and provides notes on the habitat of three species of the genus Onychargia Selys, 1865 in Vietnam, including the description of a new species, O. hungeri sp. nov. (holotype ♂, 10.52238° N, 107.47591° E, altitude 41 m, Binh Chau-Phuoc Buu Nature Reserve, Ho Chi Minh City, southern Vietnam), which is described based on male and female specimens. The new species can be easily distinguished from two other congeners by having smaller body size, U-shaped pruinosity on male’s synthorax and differences in the male’s appendages structures.