This one is a really nice, classic Pangoniinae with the long proboscis from the first batch of French Guianan flies. Keith Bayless has suggested that it is Fidena (Fidena) sp. from the tribe Scionini.
Here is the largest and grandest tabanid I have found so far in the French Guianan samples. The body length is about 18mm. This one is destined to go to Theo Zeegers in Holland, who gets all my tabanids. Keith Bayless has suggested a genus of Fidena, in the tribe Scionini.