Asiagomphus, two different new species?*

*This entry was adjusted on January 1, 2020. In August 2018 I published an article on Asiagomphus species in Vietnam in Zootaxa. By then I had verified 8 species of Asiagomphus in Vietnam, several of which were new to science and others were not previously recorded from the country. I did not want to change the 'historic' entry below that reflects my first ramblings when confronted with specimens of this tricky genus in Vietnam, so I left it as it is, but added the proper scientific names for the species involved between block-marks. (These are Asiagomphus auricolor and A. superciliaris.)

I already posted on an Asiagomphus species occurring at Huu Lien Nature Reserve. Until now I only had a female in hand. Useful, because the horn on the occiput immediately helped to eliminate most possible species. It was however pretty much impossible to say more on the specific identity.

On May 1 I went again to Huu Lien with the objective of catching the male. I saw a great many (15+), but this is a wary and large insect and I was clumsy too, so it took a while before I finally was able to catch one.

Later that morning I ran into another Asiagomphus male, perched on a stone in the stream, something the other Asiagomphus had not done, always sitting on leaves and branches over the water or hovering and patrolling above the stream. It seemed smaller and darker. And luckily this one specimen was not as difficult, to I was not that clumsy, or both. Anyway, I was able to catch it.

With this, trouble only started. It is clearly another species, but which one? Interestingly, both males share the pattern on the abdomen with transverse yellow lines at the sutures between the segments, and do not have longitudinal lines. The also lack a antehumeral stripe, and the second male even a spot. This is a pattern shared with A. xanthenatus acco [= Asiagomphus acco], which otherwise of course is very different, with a ventral tooth to the upper appendages and largely yellow S1-2. For now, I am at a loss. There seems to be no direct hit with any of the known species in the larger region. The occipital pattern of the female rules out most species for species 1 and species 2 is so dark, it is also different from any others. Of course, most species display quite a bit of geographical variation, or in the details of the appendages. This does not make things easier, but my hope is that scholars with experience of many of the Chinese species may be able to say something on the subject. My gut feeling however is that these are both undescribed species.

Possible species in the area include A. auricolor (Fraser 1926, only one female known, I do not have the description, but it is apparently from "Tonkin")*, A. hainanensis, A. pacificus, A. pacatus, A. perlaetus, A. septimus, A. takashii, A. giza, A. xanthenatus acco and A. x. xanthenatus. I have no match. Suggestions are very welcome.

Measurements:
Species 1 TL 63mm, Abdomen (+app) 47mm, HW 39mm
Species 2 TL 57mm, Abdomen (+app) 41mm, HW 33mm

* I received a copy of Fraser courtesy of Matti Hamalainen. The synthorax pattern of the female in the description is reminiscent of species 1, but lacks the antehumeral spot. The measurements are also off (abdomen length 45mm, mine 50mm). It has all yellow S1-2. Therefore species 1 is not A. auricolor [subsequently I could establish that it is].

To fresh up our memory, the female of Asiagomphus species 1 [=A. auricolor], with two horns over the lateral ocelli and one on the occipital ridge

The vulvar lamina of the female Asiagomphus species 1 [=A. auricolor]

Asiagomphus species 1 [=A. auricolor], with antehumeral spot, large posterior hamulus, second lateral stripe, lots of yellow on S1-2

Asiagomphus species 2 [=A. superciliaris], no antehumeral spot, no second lateral stripe, small posterior hamule, S1-2 dark dorsally

Here the two species scanned in dorsal view. Species 1 [=auricolor] is on the top left.

Species 1 [=auricolor] appendages in dorsal view

Species 2 [=superciliaris] appendages in dorsal view

Species 1 [=auricolor] secondary genitalia, note especially posterior hamule

Species 2 [=superciliaris] secondary genitalia, much smaller posterior hamule with inconspicuous hook

Species 1 [=auricolor] appendages in ventral view, very widely separated inferiors in broad basin like U-shape

Very different inferior appendages, shallowly cut in V-shape [=superciliaris]

Species 1 with stump superior appendages [=auricolor]

Species 2 with sharp point to superiors [=superciliaris]

Species 1 [=auricolor], black labrum. Note the flat area between the two bumps behind the ocelli

Species 2 [=superciliaris], black labrum. Note the gentle V-shape between the two bumps behind the ocelli and the hump on the occiput

The problem with penises. They all look alike. Species 1 [=auricolor], distal segment

Species 2 [=superciliaris], distal segment