Tramea transmarina euryale

During a visit to Van Long Nature Reserve, Ninh Binh, last weekend, I stumbled into a Tramea with hardly any basal markings in the hindwing. Because Tramea virginia has very extensive markings it seemed likely that this was another species. In hand the primary and secondary genitalia proved that it was indeed another species, likely none other than T. transmarina euryale, possibly its first record for Vietnam. T. transmarina euryale is known for the limited extent of the basal markings in the hindwing, but in this specimen it is even more restricted than normal. That it is not just an aberrant T. virginia is shown by the close-ups of the hamule. 

T. transmarina euryale is widely distributed in south-east Asia, known for instance from Thailand, Cambodia and Hong Kong,  even ranging to Japan, and its occurrence in Vietnam was to be expected. 

Tramea transmarina euryale, male

Tramea virginia, male

Hamule and genital lobe, T. transmarina euryale

And for comparison, hamule and genital lobe, T. virginia