Heliocypha biforata biforata (Selys, 1859)

Very similar to H. perforata, they are also black and cobalt-bluish marking damselflies. Their wings are narrow like H. perforata but the iridescent areas on the wings are broader. Males of the species are distinct by markings on the synthorax and the abdomen. The abdomen of male is stouter than it of H. perforata, with distinct blue markings on lateral side of each segment. Females have no valuable in identification of the species. Their habitats, territorial and courtship behaviours are very similar to it of H. perforata, but H. b. biforata prefer opened running waters. They are widespread species but distribute locally.

Young male, photographed by Cuong Do, Quang Binh

Thorax marking of full mature male, photographed by Cuong Do, Phu Yen

Heliocypha perforata perforata (Percheron, 1835)

The black and cobalt-blue damselflies, they are similar to H. biforata generally. The triangle on mesepisternum on synthorax is smaller than it of Aritocypha fenestrela and there is a pink marking on the posterior edge of prothorax as well as on two sides of the synthorax. Thorax and abdomen are marked with white cobalt-bluish at lateral view. The mid and hind legs of male are black with white tibia. Same to H. biforata, wings of H. p. perforata are narrow in comparing to A. fenestrella but the iridescent area on the wing of male is smaller than H. biforata. Blue markings on the abdomen of male are also good characteristics to separate this species to H. biforata. The colour of male changes in stronger after teneral stage. The female are less colourful, they are black with cream-bluish mark on thorax and smoky hyaline wing, and the external morphological characteristics of female have no value in identification of the species.

They live in swift and high concentrate of oxygen flowing waters in primitive forests or secondary forests. Male are active flying insects, their territory is around floating timbers or rocks on water surface while female usually perches on higher positions. They are not too common species but distribute nearly whole the country.

 Male with red parasites, photographed by Cuong Do, Huu Lien, Lang Son

Two males in flying dance, photographed by Cuong Do, Hu Lien, Lang Son