Austrophorocera cf. yahuarphrynoides (Townsend) (French Guiana)
This one keys out nicely to Austrophorocera but this determination will need confirming. The abdomen has a fascinating and highly distinctive tuft of orange hair on the genitalia.
EDIT (5/01/2011): Monty has confirmed this genus and said that the tuft of hairs looks like A. yahuarphrynoides (Townsend) but there are apparently a few similar species.