There is another genus that I considered, the very rare Psephactus that found from Taiwan, Japan and Malaysia. However I quickly found that my material can not be Psephactus because its elytra, not same to Psephactus, my material with long elytra and not as short as all member of the genus. So only one male of my collection not yet known in genus level and maybe something very rare. I continued searching all the genus that closes to Drumontiana, in the area, there are only 2 genera of the tribe Mecroscelisini that not be confirmed with my specimen: Hystatoderes and Sarmydus. But the Sarmydus is clearly separated by the short tibia and tarsus, the antenna also very depressed. Then the last confusing is Hystatoderes, a genus with single species H. weissi by Lameere in 1915, under the genus Emphiesmenus.
On the species H. weissi, this species is well known with the female rather than the male, my material is male specimen. In the original description, Lameere described this species base on a single female that collected from North Vietnam, the specimen was deposited in Paris Museum of Nature. I try to find the photo of the female in the Museum website but it did not worked, no photo at all.
Making some emails to my fellows, Francesco, Antonio and Mikhail, I got the paper by Drumont et al. with the reviewing of the genus Emphiesmenus in 2000 from Francesco. In the paper, Alain and his fellows confirmed about the female specimen that Lameere described as vitalisi in 1917 is the synonym of weissi and the species be placed in the genus Hystatoderes. The photo of the female also given in Drumont et al. paper. In my database, Ziro sent me his pdf before, the Komiya and Nisanto, 2001 in which the male and female photos of the species be published, however the photo of the male is very poor and look like there is only one lateral spine on pronotum. The full structure of the male had not been known and I did have to continue finding the description.
Antonio helped me some descriptions of the female H. weissi and he suggested that the male description should be published by Gressit and Rondon in 1970. And it is the reason why the species be recorded in Laos. I emailed to Mikhail and asked him about the paper because Antonio did not have this book with him that time. Milkhail replied that he could not find any Hystatoderes in the book, I asked him try again with Emphiesmenus. Mikhail sent back to me later the description of the male of E. weissi, very clear and understandable structure with black and white photos of both male and female. My specimen is true H. weissi and all the characteristics matched very well with the description.
So happy with the result, my material male is true H. weissi and recorded the first time in South Center of Vietnam. I did hope that maybe it is a new species because Sa Pa and Hoa Binh are two sites of type specimens but very far from center of Vietnam. And in the Komiya and Nisanto paper, the pronotum looks only has 1 lateral spine. Now everything clear enough to understand, H. weissi the only species of the genus can be found not in a narrow area, maybe in the past, the species quite common in the Indo-China region, my opinion maybe this species can be found in Yunnan, or South of China. It is not a new species, but interesting taxon in my collection.
Hytatoderes weissi Lameere, 1915 (Do Collection)
The first description of the male by Gressit and Rondon in 1970.
Thank you so much to my fellows and friends: Francesco, Antonio, Ziro, Alain and Mikhail for helping me.
Note: There still a confusing, it is the photo of the male in Komiya and Nisanto paper, the male in my view looks only with a single spine on lateral side of pronotum and two composed eyes of the specimen looks not close together. Until the specimen in the paper be confirmed, I have not been sure about the taxonomical position of the species that gave by Komiya and Nisanto.