the pics Aurthur Lee Jacobson posted on his website are of B. armeniaca (his plant from Logees)...that is the only species they propagate.
they are easy to tell apart...argentea has stiff, shiny, elliptical leaves, with round fruits...
armeniaca has flimsy, lanceolate leaves, that are not shiny.
read this from Arthur's article...he states the same thing that I've been harping on for years now(about B. argentea)...
Native in Bolivia, Brazil, Colombia, Costa Rica, Ecuador, the Guianas, Panama, Peru, Venezuela. A Kichwa (Quechuan language variant) name is Wanpula panka. Spanish names include: Ciruela del monte --translating Mountain Plum; and Marmelo. In English, we call it Peanut-Butter Fruit.
George Don in 1831 wrote that its twigs were minutely hairy; leaves lance-shaped, glandular, and silvery beneath; and that it had been cultivated since 1810. The Latin name argentea means silvery.
The Flora of Suriname 1976, gives a technical description that I here paraphrase: Small tree [it can reach 65 feet tall] or shrub; young parts and flower clusters densely appressed-hairy; leaves densely silky on both sides, later hairless above; ovate or oblong; up to 16 by 9cm [6.25 by 3.5 inches]; 2(3) glands 1-2cm above the leaf base. Fruit silky.
Clearly, this species, despite being listed in many books, catalogs and websites, is in fact never cultivated, and plants so-called are really either B. Armeniaca or B. glandulifera. It has hairy fruit. I suspected this, and it was confirmed by the expert botanist Dr. William R. Anderson, of University of Michigan's Herbarium; he is writing a monograph on the genus Bunchosia, and kindly supplied accurate corrections to my first draft of this article."
but, Jacobson is wrong, argentea has been cultivated, it's just not as common, because it doesn't perform as well over a wide range of growing conditions (unlike armeniaca, which can fruit in FL or CA). I suppose argentea struggles because of low elevation, and high humidity...much like Cherimoya or Lucuma.