Polycanthagyna erythromelas (McLachlan, 1895)

Polycanthagyna erythromelas is one of the 4 Aeshnids I encountered the most in the Hanoi area (sensu lato, i.e. within a 60-70 km radius)- with Tetracanthagyna waterhousei, Gynacantha subinterrupta and Anax guttatus. If the two latter species are commonly spotted in agricultural landscapes, along ponds, the two former ones are strict stream forest-dwellers.

A resting male, photographed at a tiny pond in secondary forest (foothills of Tam Dao)

P. erythromelas is a dragonfly of very large size (wingspan of about 120 mm), with striking colours: male dark, female coppery red, both yellow striped.
The strongly contrasted sexes and their powerful build make a pair of magnificent insects.

According to literature, P. erythromelas is quite common in suitable habitat across much of its range. But for me it is an uncommon sight (4-5 sightings in 3 years) - like other jungle Aeshnids I could say, due to their inconspicuous nature.

Male and female were observed at forest ponds or streams, the latter as she was coming to oviposit in soil in steep banks or wet mossy rocks. 

Male :

Face greenish, upper surface of frons, vesicle, occiput black.

Thorax dark, broadly marked with bright yellow as follows : moderately broad antehumeral stripes, two broad bands on each side, one on middle of mesepimeron, the second, much broader, covering nearly the whole of metepimeron.

Wings, male.

Wings hyaline, very long and rather pointed at apices.

Abdomen black with yellow markings, tumid at base, markedly constricted at S3, then very gradually dilating to S7.

Anal appendages:  superiors black, coated with long thick hair on upper surface; inferiors simple, triangular, curled upward.

Tip of abdomen, dorsal.

 Dorso-lateral.

Lateral.

Female :

She differs rather broadly from the male, especially in shape and colouring of abdomen. 

Thorax dark reddish, marked as the male.

Abdomen bright coppery red, yellow striped, with the intersegmental sutures and whole of terminal three segments black.

Simply beautiful. That's all I really have to say.

Large robust ovipositor, extending nearly to end of abdomen; dentigerous plate produced and furnished with a number of variably sized robust spines, longer and more robust at apical border. Like Tetracanthagyna, the female oviposits in dry soil, the powerful ovipositor and pitchfork-like dentigerous plate being adapted for this purpose (Fraser, 1933).

End of abdomen of an ovipositing female, covered with soil. 

P. erythromelas is a widespread species, known from India and Pakistan, Nepal, Thailand, Myanmar, China, Thailand, Laos and Vietnam.

I found it in both primary (Cuc Phuong NP) and secondary forests, sometimes in intermediate-aged secondary forests (<30 years).