Nudibranch from New Zealand.

August 10, 1998
From: Ross & Diane Armstrong

My wife and I photographed this (we assume it is a nudibranch) on a night dive in Nursery Cove at the Poor Knights Islands on 31 January 1998. The depth was about 12m.
We have been unable to identify it.


Ross and Diane Armstrong

Armstrong, R. & D., 1998 (Aug 10) Nudibranch from New Zealand.. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

This is a species of nudibranch belonging to the Suborder Arminina. Some of the more common genera you will find illustrated in books are Caldukia, Madrella and Janolus. The zephyrinids feed on encrusting and arborescent bryozoans (lace corals) and appear to be fairly specialised feeders, each species specialising on a particular food species. We don't know what this species feeds on.

Zephyrinids all have tapering tubular cerata on their backs, much like the aeolids. In many species the cerata can be cast by the animal when it is disturbed.

I am not totally confident of my species identification, but hopefully, Richard Willan, who is an expert on this group in New Zealand, will see this and confirm or correct my identification.

Galeojanolus ionnae differs from other zephyrinids by having somewhat swollen pustulose cerata but it is difficult to be sure from your photo.

Unfortunately a hiccup in our computer cutoff your email address. Could you please let me know what it is. ... Bill Rudman

Rudman, W.B., 1998 (Aug 10). Comment on Nudibranch from New Zealand. by Ross & Diane Armstrong. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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