Sinorogomphus nasutus satoi (Asahina, 1995)

Male resting vertically near a stream, Ba Vi NP, May 2013 

These shots were taken during some field trips at Ba Vi National Park in May. Males were on territory, rather slowly coursing up and down a well-shaded stream, at some dozens of centimeters above water’s surface, and sometimes were observed perching vertically on the stems of plants like cordulids. I had many sightings during sunny days and none when the weather was overcast.

The male of this species can be confidently identified by the general maculation pattern and the structure of the anal appendages. 

It is a large-sized species. Synthorax black, both sides being striped with  bright yellow markings. Wings smoked pale brown in aged insects.

Male, head from different angles. Note the frons triangularly protruded.

Caudal appendages black, superior one (=cerci) deeply bifurcate, the inferior (=epiproct) widely opened with bifid apices.

Dorsal view

Dorso-lateral view

Lateral view

 Male
The yellow pattern on the basal two segments of abdomen is characteristic of this subspecies, described based upon specimens collected at Tam Dao.

 Female

 Female, face

Left: female caught when ovipositing over a shallow gravel section. 

Right: valvula valvae broadly trapezoidal with middle part of apex sharply pointed

Wings, male

 This species is widespread in east, south and southwest China, and has only been recorded from a very few localities in Vietnam : Tam Dao and Ba Vi.

At Ba Vi, the specimens were found along shady streams and brooks with rocky substrate, through secondary forest (but unexploited, with closed canopy), at ca 900m a.s.l., together with Chlorogomphus auratus.