The Atemoya, a hybrid of the Sugar Apple and the Cherimoya, is a member of the Annonaceae family. The fast growing tree has a short trunk, drooping
branches holding deciduous, elliptical leaves and tiny yellow triangular flowers that develop into heart shaped fruit. The fruit pulp is snowy white with a sweet taste and fragrance. The cross was developed in Miami in 1908 producing the hardiness of the cherimoya and the seductive taste of the sugar apple. The Atemoya thrives in a variety of soil but best results come from deep, rich loam. Irrigation during fruit development increases size and quality of fruit. 

Atemoya is best eaten chilled. Half a fruit and spoon out the fruit pulp. Seeds should not be eaten. A fruit contains 94 calories, 1-1 1/2 g protein, 24 g carbohydrates. The fruit is a good source of potassium, protein, and
carbohydrates.

Atemoyas will split at the ends and the skin color will darken when the fruit is ripe. These are not signs of declining quality. The fruit should be stored and displayed at room temperature. Cracked fruit should be overwrapped and labeled with ripe stickers.

http://www.fl-ag.com/commodities/atemoya.htm

http://www.hort.purdue.edu/newcrop/morton/atemoya.html