In the mid-1980's, Laurence Zill, sometimes accompanied by his son Gary, collected red Annona reticulata varieties in Belize and northern Guatemala. These Custard-Apple varieties he usually named after the town or community where he got graftwood. These included 'Sarteneja' from the town of Sartenaja, 'Chonox,' 'Benque,' 'Canul,' and 'San Pablo,' all from Belize (so not from a state of Brazil), and Tikal (not from the actual ruins). Gary Zill later returned alone to northern Guatemala and collected the 'El Remate,' 'Tart,' and 'León,' named in honor of Dr. Jorge León, eminent plant collector in Central America, who provided us with a lot of initial guidance.
The Zills sent me to western Guatemala several times. I collected varieties of ilama, Annona diversifolia, including 'Genova Red,' and Genova White,' both from the town of Genova, 'Guillermo' from the yard of a man by that name near Retahuleu, and 'Pajapita' from the town of that name near the border with Mexico.
On cold hardiness--- several degrees of difference can be made by the general condition of the plant and the abscence or presence of other stressing factors, and by presence or lack of frost-nucleating bacteria or other particles.