First reported in Canberra in 2016 (https://www.canberratimes.com.au/story/6039072/queenslands-bladder-cicada-lands-in-canberra/). Most likely introduced in pot plants. The established population in Sydney may have also resulted from a similar introduction about a decade earlier.
Cystosoma saundersii is listed in the following regions:
Canberra & Southern Tablelands