This species was described by R. Martin in 1904 base on specimens collected from
. Tonkin, Vietnam
They are medium-large sized damselflies and the heavy body is unicolour shining black. Their elongate wings are dark at haft base and tip.
They live in open opaque rivers with mud and sand bottom layer; the males are active and highly territorial. They fold their wing at rest but many times the clap or open the wings under strong sunlight above the water surface. Mostly the damselflies fly not far from their breeding habitats but some time they fly very high and perch high above on vegetation beside the rivers.
Male, photographed by Cuong Do, Mai Chau, Hoa Binh