Sorry Riverland, South Australia I see and not the northern hemisphere where. most people are on the forum. I am almost at the northern limits for quite a few citrus and chopped out minneola, imperial mandarin and navel which can't handle wet tropics and the fruit are crappy. Generally the same variety of mandarin or orange will have thinner skin, higher sugar to acid ratio, larger fruit and less skin colour at the most tropical end of the tolerance compared to towards the cooler tolerance limits.