Bill, your Mitoyo looks like Aswad to me.
When I grew Mitoyo, the fruit had a black calyx and was a bit skinnier in shape. Still a squat teardrop, but less round and more bottom heavy.
Here you can see a Mitoyo in front at center left (it was a late season fruit that I let go a bit long on the plant) and right next to it an Aswad.
Here are some pics of the plant:
For comparison, here are some pics of my Aswad:
FWIW, both were excellent, just in different ways. Mitoyo was creamy and delicate and the sweeter of the two, and Aswad was really meaty and richly flavored. Neither seemed to get bitter even when left too long.