February 23, 2001
From: John Chuk
Once again I seek your help in identifying a nudibranch. This one was photographed on a night dive at Portsea Pier, Victoria, on 19 December 2000. The specimen is 7mm in length and is covered in inflated papillose cerata. It was found at a depth of 4.5m, apparently feeding, on an arborescent bryozoan attached to a pylon. A portion of the bryozoan is visible in one of the photo's.
My guess would be a zephyrinid and possibly a Janolus sp.? Your opinion would be appreciated!
Many thanks for your help.
email@example.comChuk, J., 2001 (Feb 23) Zephyrinid from Victoria, Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/3772
This is certainly a species of Janolus as can be seen by the tuberculose crest between the rhinophores.
One species with tubercules on the cerata has been reported from Victoria previously. and it has been identified as the European species, Janolus hyalinus, which Miller & Willan (1986) also report from New Zealand. As far as I can determine, that species in Europe does not have the blue and yellow pigmentation visible in your animal.
I wonder if it is the New Zealand species Janolus novozealandicus (Eliot 1907) which is characterised by blue and gold bands at the ceratal tips, and pustules on the cerata. The body has brown and opaque white patches, and grows to about 40mm.
In Miller & Willan's review they say " The closest known species to Janolus novozealandicus is J. hyalinus ... features in common are ground coloration, pustulose cerata, unbranched ceratal diverticula, .... However the two differ in several points ... J. novozealandicus has blue pigment on the sparsely pimpled cerata, a lozenge shaped patch of opaque white immediately behind the caruncle .....'
Your photo has both the blue on the cerata and the white patch behind the caruncle.
• Miller, M.C. & Willan, R.C. (1986) A review of the new Zealand arminacean nudibranchs (Opisthobranchia: Arminacea). New Zealand Journal of Zoology, 13: 377-408.
Any comments and photos from people familiar with either species would be welcome