I have one of these trees, orr I think I do.
It was identified as Citrus reshni, aka Cleopatra mandarin. My property was a Citrus grow in the 1960s and a few trees are still growing since then. In the past (currently) Cleopatra mandarin was (is) widely used as a rootstock. It is now 12-15 feet and bears fruit regularly.
Although, I'v lost two other Cleopatra mandarin trees due to the drought 2016-2017