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

Libellago lineata (Burmeister, 1839)

Name of the species was named after C. Linnae, the father of taxonomy who developed the natural systematic.

They are tiny damselfly with two colours of the body of the males: deep black and brighten yellow. Wings are hyaline with orange-brownish at base and the fore wing has an apical dark spot. The species are one of smallest of chlorocyphid damselflies. The thorax of male is deep black with brighten yellow strip markings on both dorsal and lateral sides. Legs of male are black with while tibia on ventral side. The abdomen of male is somehow depressed with light yellow marking dorsally on basal and middle segments while the apical segments are deep black. Female of the species is stout and duller and simpler in colour with hyaline wings and fade pterostigma. They inhabit at running waters in secondary forests or opaque rivers. Males commonly protect their territory around fallen timbers, and mate with arriving females. Females oviposit into the floating logs.

Male, photographed by Cuon Do, Mai Chau, Hoa Binh

Male, photographed by Nguyen Ba Quang, Ma Da, Dong Nai Province 23 August 2015

Female, photographed by Nguyen Ba Quang, Ma Da, Dong Nai Province 23 August 2015

Rhinocypha watsoni Tol & Rozendaal, 1995

In 1995, Tol and Rozendaal described this species base on specimens collected from Bach Ma National Park, Thua Thien Hue Province. Recently, this species also were recorded in Khanh Hoa Province and it made their distribution had been known wider to the south of the country.

They are small damselflies, with nearly unicolour body. The head is dull black; the thorax is dark with red dark brown marking and yellow strip marking on lateral side of the synthorax. Legs of male are black, with white inner side tibia of middle legs. In male, fore wings are hyaline but hind wing hyaline with an iridescence area at tip. And in the iridescence area, there is a distinct apical metallic blue flash spot. Females are fader than males with dusk hyaline wings.

This damselfly was found in the centre to south of Vietnam in the forests on high mountains with elevation from 700 to more than 1000m. They are found next to shaded clean streams in pristine forests; usually share their habitat with D. cyanocephala. Particularly we found them in Hon Ba Nature Reserve, Khanh Hoa province as they were flying in the jungle at the coming out area of underground streams.

The damselfly is somehow active species, males usually perch middle or high above that water surface but they do not fly far from breeding sites, where are clean and swift flowing streams.

Male, photographed by Cuong Do, Bach Ma National Park, Thua Thien Hue

Rhinocypha seducta Hamalainen & Karube, 2001

Base on specimens that were collected from Bao Loc, Lam Dong Province, in 2001, Hamalainen and Karube described this species as a new for science. Now, their distribution was reported in many localities of high land in south of the country.

It is colorful and enigmatic species, a rare species but quite common locally. Males and females are similar but females are lightly duller. In males, the head is deep black with orange-red spots marking, the thorax dull black with dark orange-red strips on thorax on both dorsal and lateral sides. The fore wings are hyaline; each hind wing is hyaline with an apical iridescent spot. The abdomen is somehow elongate, dull black and unicolour.

The species lives in pristine or lightly disturbed forests on high lands of Southern Vietnam, where the temperature is not too high and they are very humid forests. The mature forms do not fly very far from their breeding sites, so they are not so active insects. Males of this species usually perch up above the water which is muddy streams. They fly up and down and spend most of the time for perching on leafs or branches of trees above the stream. They are very sensitive to temperature and humidity of environment. They usually perched very high up to the canopy, and they got down gradually as sunlight went directly to the surface of the forest. Hiding in deep shade of the forest, they got down and perched near the stream where the humidity high enough. But immediately, after the sun was covered by clouds, they flew up to the higher positions. Their territory is very narrow area but they some time have vivid courtship daces, the male try to protect his own territory by showing to his neighbour the golden flash spots of his hind wings and the action just little above the water surface.

Male, photographed by Cuong Do, Da Lat, Lam Dong

Face and thorax of male, photographed by Cuong Do, Da Lat, Lam Dong

Aristocypha fenestrella (Rambur, 1842)

Aristocypha fenestrella is one of the odonate species with wide range of altitudinal distribution (0-1700 m). It is one of several common mountain stream damselflies and widespread species.

They are small glittered damselfly with broad violet wings. The body of male is deep black basically with some yellow stripes on thorax and a particular triangular purple marking on dorsal of synthorax. Head is uncoloured black in both male and female with the swollen clypeus as characteristic of the family. Fore wings are narrow, hyaline and some how brownish and hind wings are much broader, with shining violet cell areas insert into dark background. Wings of female just are hyaline or hyaline-brownish. Legs of mature male are very typical with tibia developed to be broader and white coloured. The colours of teneral males usually are fader than it of mature forms.

Those damselflies usually are found in the primary forests, the mature forms fly around their breeding sites which are clear, swift streams. Although they are forest species, this species is quite common, they are widespread species and could be found in whole of the country.

It is one of the most active species of the family with and males are strict territorial individuals. Each male usually appropriates a micro-habitat (a rock, floating timber or a branch of tree..) near the water surface. And when another male enters his territory, rival flying dance will be observed. In courtship flying dance of male and female, or rival flying dance of males, the male usually stay-flies in the air and shows his flash violet hind wing and white tibia of his legs to the partner. A territorial flying between two males take place from some second to many minutes.

Larvae of the species live in sand, gravel swift streams; they are very typical with two long filament gills at the end of abdomen.

Young male, photographed by Cuong Do, Ba Vi National Park

Mature male in full color, photographed by Cuong Do, Hon Ba, Khanh Hoa

Mature male in full color, photographed by Dang Ngoc Tu, Tu Son, Hoa Binh

Female, photographed by Cuong Do, Hon Ba, Khanh Hoa