Gononemertes australiensis is a parasitic ribbon worm.

[1] It lives commensally in the ascidian Pyura pachydermatina found in the sublittoral waters of the New Zealand.

G. australiensis was found in specimens of P. pachydermatina collected in Sydney harbor.

[note 1] These worms were found specifically in the atrium of P.

Each of its gonads produce several oocytes while the male worms carry testes along its parenchyma.