Acanthacorydalis fruhstorferi is a species of dobsonfly native to Vietnam and China. It holds the title of largest aquatic insect by wingspan according to the Guinness Book of World Records at 21.6 cm. The title formerly belonged to the Brazilian damselfly Microstigma rotundatum.

Acanthacorydalis fruhstorferi was first described by Herman Willem van der Weele in 1907 from a specimen from "Than-Moi" (probably in Lạng Sơn Province), Vietnam. It is found throughout Southern China (Fujian, Guangxi, Guangdong, Guizhou, Jiangxi, Yunnan, and Zhejiang) and Northern Vietnam.

Liu and associates proposed in 2005 that the species is most closely related to Acanthacorydalis sinensis citing morphological similarities relative to similar Chinese genera of Acanthacorydalis. Specifically the wing and body colouration, yet differed by A.sinensis's lack of sagittal dorsal division.

...