South Australian Senator Skye Kakoschke-Moore of the Nick Xenophon Team is standing down, having become the ninth casualty of the dual citizenship debacle.

"I am resigning from the Senate today and will request that this matter be referred to the High Court when the Senate meets next week," she said in Adelaide.  Despite being born in Darwin, it turned out she is a dual citizen by descent.  Section 44 of the Australian Constitution says dual citizens cannot serve in the Federal Parliament.

"Today I have received confirmation that I am a dual citizen as I have inherited British citizenship from my mother.  I am heartbroken by this news.  My mother was born in Singapore in 1957 to British parents," Ms. Kakoschke-Moore announced in Adelaide. 

The byzantine rules of who is and who isn't a dual citizen appears to have snuck up on Kakoschke-Moore, as the family believed this was cleared up a long time ago when they were living in Oman.  At that time, her father had sought a British passport for his daughter.  But the UK said she was ineligible not only for a passport, but also for UK citizenship.

"It was always my understanding I was not a British citizen," she said. 

She joins the list of lawmakers who've either stepped down or been ruled ineligible:  Former Deputy PM Barnaby Joyce and Fiona Nash of the Nationals, Stephen Parry and John Alexander of the Liberals, One Nation's Malcolm Roberts, independent Jacqui Lambie, along with Greens Larissa Waters and Scott Ludlam fill out that roster.  Joyce and Alexander are currently campaigning in by-elections to regain the seats they were forced to surrender.