This is noteworthy, its occurrence in Vietnam, because its occurrence in the south of China, although reported, has been questioned. The species has a wide distribution, ranging from Nepal to Japan, but generally is believed to be a more northern type of gomphid.
That is why it was an even larger surprise that I ran into it again on June 23 just below Sa Pa in Lao Cai. Which means that it cannot be that rare and must be rather widespread. Here too I found it at a rocky stream in relatively open terrain. At least 7 males were present.
There are several Anisogomphus species in Vietnam. Besides the relatively uncommon Anisogomphus koxingai that also includes Anisogomphus tamdaoensis, which was placed in the wrong, but closely related genus Merogomphus originally, but now placed in Anisogomphus. In fact, it would not surprise me if it would turn out to be a junior synonym of Anisogomphus pinratani from Thailand. The two species are very similar, to say the least. Anisogomphus tamdaoensis is a widespread and common species. And then there is the Anisogomphus sp. novum that I first saw at Pia Oac. As a matter of fact I saw a female at the same place as where I first saw Anisogomphus maacki. That location is actually not that far from where I saw this unknown species first (about 40-50km).
|Male Anisogomphus maacki, with widely expanded S7-9 and big yellow markings, although quite reduced on S9.|
|Another shot of the same individual from Cao Bang|
|Close-up of the thorax and head of a different specimen|
|S7-10 and appendages in dorsal view. This specimen even less yellow on S9|
|Face of the same second specimen from Cao Bang|
|One of the males from Lao Cai. Note the large spines on the distal part of the femur of the last pair of legs.|
|S7-10 and appendages in dorsal view, this specimen clearly with more yellow on S9|
|Scan of the Lao Cai specimen|