Thursday, 21 November 2013

Macrogomphus rivularis, maybe - but no, Labrogomphus**

Martin in 1904 described a large Hagenius species, now put in the genus Sieboldius. The description has no plates and is of a male, found in Tonkin. Do Manh Cuong et al. described males from Cuc Phuong and also recorded it from Huu Lien. We observed several very large aeschnid-like dragonflies that turned out to be female Gomphids looking for places to oviposit along a moderately large stream in open country close to a forested karst mountain. I could take a few shots with the telephoto lens, but with my new camera and all that, the settings were wrong. However, what can still be seen is the double yellow band at the base of S7. So, I concluded these were likely Sieboldius gigas. But I consequently found out the Cuc Phuong record was later ratified, in fact it is Megalogomphus sommeri, and checking other records of that species, that seems a better match! I am sure we will run into it for better shots next time. It was interesting to see gomphids this late in the season. Of course Ictinogomphus pertinax, but also Paragomphus capricornis was still around.

*Matti Hamalainen sent me a photo of female Megalogomphus sommeri and pointed out that the shape of the abdomen was not consistent with that species. I have to concur. He also suggested it might be the rare Macrogomphus rivularis and yes, the long S9 seems to suggest that genus. All the more reason to try to relocate it.

** Well, we now know that it is another genus with very long S9, but new to Vietnam, Labrogomphus

Labrogomphus torvus, female

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