Two Davidius species

May 11 in Yen Bai Province I was checking a stream in relatively good forest. The stream split into smaller streams, heavily vegetated with shrubs along it. In one stretch I found 4 small gomphids. I was able to get some photos and close-ups. Interestingly, these all were perched on leaves. Later on, I found superficially similar gomphids, but seemingly even smaller and with different pattern. For instance, the antehumeral spot was missing. Interestingly, the 3 specimens I saw were perched on rocks in the sun, one obilisking magnificently. Checking at home both were Davidius gomphids. Coincidentally, that is genus 100 to feature in this blog!
3 species of Davidius are known from Vietnam according to Do & Dang (2007). These are D. fruhstorferi, D. trox and D. monastyrskii. My two species fitted very well with the first two species.

Davidius trox, male

Davidius fruhstorferi, male

Davidius trox, male. Note the antehumeral spot.

Another Davidius trox in dorsal view. Perched on a leaf.

Male Davidius fruhstorferi, perched on a stone in the open

Davidius trox, appendages in lateral view

Davidius trox, appendages in dorsal view 

Davidius trox, appendages in ventral view

Now compare Davidius fruhstorferi, appendages in lateral view

Davidius fruhstorferi, appendages in dorsal view

And the same, in ventral view

Penile organ of Davidius fruhstorferi

The same of Davidius trox, actually very much not the same