It's interesting that Poncirus polyandra shows a bit of similarity to citranges. P. polyandra isn't considered to be a Citrus- Poncirus hybrid, but either a sister species to P. trifoliata, or perhaps ancestral to it. In some aspects it's apparently intermediate between Citrus and P. trifoliata, or perhaps closer to Citrus than P. trifoliata is.
Having suggested this, I have no experience with P. polyandra, and haven't seen it.