Surprisingly, yesterday was rather sunny and I had another shot at various gomphids. I was able to catch two Nihonogomphus specimens and was struck by the differences with the Nihonogomphus schorri specimen from Xuan Son the other day. I doubt whether the differences are large enough to warrant a discussion of the species level, but it is an interesting case of geographical variation or inter population variability.
First, here is a Xuan Son specimen photographed perched and one from Huu Lien.
|Xuan Son, Nihonogomphus schorri, male, April 13|
|Huu Lien, Nihonogomphus species, male, April 26|
|The Huu Lien specimen in hand, different from the one perched in the photo|
|Xuan Son specimen in hand, also different from one perched in photo|
What can already be seen here is the difference in shape of the first segment of the penile organ. Let's pull that close:
|Huu Lien Specimen 1, look at the hook directed posteriorly|
|Huu Lien Specimen 2, identical hook|
|Xuan Son Specimen, no hook, just pointed straight down|
|Huu Lien Specimen 1, appendages in ventral view. Note the inferior appendage is not spread and although bent upwards, reaches the shoulder of the superiors.|
|The Xuan Son specimen, spread in a V and falling short clearly off the shoulder of the superiors|
|Second Huu Lien specimen, identical to the first specimen|
|Dorsal view Huu Lien specimen 1|
|Dorsal view Huu Lien specimen 2|
|Dorsal view Xuan Son specimen|
The lamina of the anterior lamina is also drastically different. It is, in short, a completely different structure. And the anterior hamule, with a shoulder in the Xuan Son specimen, as to be expected for N. schorri, only broadens somewhat, without a clear shoulder, in the Huu Lien specimens.
|This is a Huu Lien specimen, note the rectangular, but almost square, lamina at the bottom of the structure|
|This is the Xuan Son N. schorri. Note the narrow and clearly excavated lamina, which also almost disappears under the adjacent structure. It is very different.|