Citrus inodora hybrid
This plant produced two mature fruits for the first time in January 2019.
Although open-pollinated in my greenhouse, everything suggests this is a hybrid with a red finger lime which is also growing in the same greenhouse.
Leaf size comparison with Citrus inodora behind.
page created 6th February 2019 & 23rd May 2020
The hybrid fruit, about 7cms long, is at the top, with the yellow Citrus inodora fruit in front for comparison.
This fruit from May 2020 shows the slight internal colouration. The vesicles are similar to the finger lime parent but the taste, while still acidic, is noticeably less sharp.

Leaves are about one quarter the size of C. inodora, and the second of the dual spines is much reduced.
Fruits are slightly longer, thinner and less ridged than C. inodora.
Final skin colour suggests genes from a red-skinned finger lime.
Note the fruit shown below is slightly over-mature which shows in the depressed areas on the peel.
For some other Australian citrus hybrids see Saga University Hybrids