Known from southeastern Australia (Victoria, South Australia).
Portsea Pier, Victoria, Australia on 19 December 2000. The specimen was one of two found in close proximity on the bottom at a depth of 4.5m. It is 13mm in length. Photo: John Chuk.
First described from Victoria by Burn (1957), it was placed by him in the genus Nembrotha because of its general external appearance. It was later (Burn, 1973) removed to the genus Gymnodoris, but I know of no published anatomical information on this species. Burn mentions a spiculate skin. I doubt whether it is a species of either Nembrotha or Gymnodoris.
• Burn, R.F. (1957) On some Opisthobranchia from Victoria. Journal of the Malacological Society of Australia, 1: 1-20
• Burn, R.F. (1975) A list of the dorid nudibranchs of Australia (Gastropoda, Opisthobranchia). Journal of Zoology, London, 176: 477-517.
Rudman, W.B., 2001 (March 18) Nembrotha arnoldi Burn, 1957. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/nembarno