Lamelligomphus formosanus and Melligomphus ardens

June 8 I visited Xuan Son National Park with the hope of finding the Idionyx male of the enigma species of the week before. Not a single Idionyx crossed my path. But I was intrigued to see that next to Lamelligomphus camelus, which I already spotted last week, there was another Lamelligomphus sharing the same habitat in the same place. It was about as large as L. camelus and had spots on the labrum, unlike the L. hainanensis of Yen Bai. It had more pronounced raised edges to the apical segments, but no humps. In fact, as can be seen from the shape of the appendages, the apical segment of the penis and the thumb-like projection on the anterior hamulus, this was L. formosanus, a species I already had ran into last year. It is the third Lamelligomphus species I see this year and if we count the enigma species of last autumn, the fourth in total. Like L. camelus, it was quite active in the late afternoon, with several males hovering near the third bridge, but also above the concrete path along the river, where L. camelus was also active.

I left the park with the idea of making it to the river nearby to see if anything would fly there at dusk. I saw quite a few Lamelligomphus specimens hovering in the remaining light and because I wanted to know which one it was, I waded into the fast flowing stream. When I finally caught a few, I had a big surprise, because these were not Lamelligomphus, but Melligomphus. And under the microscope they were clearly Melligomphus ardens. The day was made complete by a fine male Burmagomphus vermicularis.

Lamelligomphus formosanus, male. A dark specimen with second and third lateral stripe fused to form almost completely black metepisternum.

A second male with obvious yellow line on metepisternum separating 2nd and 3rd lateral stripe. Note also the pattern on S2. Very different from L. camelus, rather similar to L. hainanensis.

Distinctive appendages of L. formosanus, without dorsal tooth to basal part of superiors, small teeth ventrally on close to bend and highly divergent and long inferiors. Note also the raised edges of S8-9 and the "near" hump, slightly raised middle of S8.

Same appendages in dorsal view

Another close-up of appendages of L. formosanus

The appendages of L. hainanensis for comparison. Very different tips to inferiors.

Facial pattern of L. formosanus

Rather similar facial pattern of male Melligomphus ardens

The complete insect, male Melligomphus ardens. Note the different shape of especially the superior appendages, but not easy to see in flight. Pattern on S2 very similar to L. camelus.

S8 displays minimal humps, not unlike L. formosanus.

The appendages of M. ardens. Note the light tips to the inferior appendages (this being dorso-lateral view) and large lateral tooth on inner surface of superiors at halfway point.

The same appendages in lateral view.

Finally, the small and lovely Burmagomphus vermicularis, hovering above the stream at dusk.