Adam, Carlos said it could be a relative to Annona and not to Duguetia!?!
By the way, the guy sent me these photos is going to give me more info in the next days. I suspect this will be not a bad fruit to eat when ready for ripe..
In the meantime I'm going to get from him also some fresh seeds of Annona Crassiflora now and Annona Coriacea in July
Cheers,
Giampaolo