Sue has a former student from China who says the name of my mystery fruit is "Pipa." Once I had the name in was pretty easy to find information about it. It seems it grows on a loquat tree and ripens in southern China in May (or perhaps a little earlier around Xiamen!). It is called pipa after the musical instrument -- or the musical instrument is called pipa after the fruit (you find both explanations on the internet!), and that is either because the leaves are the same shape as the instrument or the fruit is the same shape as the instrument -- you decide.
Anyway, in looking for information, I ran across this interesting article about the symbolic meaning of certain fruit in China. Enjoy!