https://www.researchgate.net/profile/Camilla-Whittington/publication/228347583_Platypus_Venom_a_Review/links/00b7d518054327fd13000000/Platypus-Venom-a-Review.pd

https://www.researchgate.net/profile/Camilla-Whittington/publication/228347583_Platypus_Venom_a_Review/links/00b7d518054327fd13000000/Platypus-Venom-a-Review.pdf https://www.researchgate.net/profile/Camilla-Whittington/pub... has a review of studies into the venom but the only source for the pain I’ve seen is the same, Fenner 1992. That said, a decent amount of painful stuff exists in Australia, so I wouldn’t be surprised; https://en.wikipedia.org/wiki/Dendrocnide_moroides https://en.wikipedia.org/wiki/Dendrocnide_moroides springs to mind.