Janolus sp.

Image courtesy of Dave Mullins
24 metres, Governor Island Marine Reserve, Bicheno, Tasmania, Australia.
Sony DSC-RX100 in Nauticam Housing with wet macro diopter, Inon Z220 strobe.

Dave Mullins on location

Janolus sp. undescribed

During some cold water diving last year whilst catching up with my old dive buddy Gary Cobb, who has moved to Tasmania, a number of undescribed species were found off the fishing village of Bicheno located on the east Tasmanian coast. I use the expression "cold water diving" only as a relative term as 13C water is cold for a subtropical diver like me.

One interesting specimen we came across in those waters was a Janolus. Our first thoughts were that it is Janolus eximius , a species that has only previously been reported from the North Island of New Zealand. It exhibits some similarity to the external features of that species however the rhinophores, caruncle and markings on the dorsum are definitely different. I consulted renowned temperate water opisthobranch taxonomist Bob Burn who is of the opinion it is an undescribed but not unknown species of Janolus having been reported previously from southern Victorian waters of Australia. Unfortunately our specimen was unable to be collected for more detailed taxonomic photos due to the dive site being a fully protected declared marine reserve.

Janolus of course are recognized by having their cerata continue uninterrupted around the anterior of the dorsum in front of the rhinophores and possession of a longitudinal elevated caruncle situated between the rhinophore bases. They all feed on arborescent bryozoans.


- Burn R. (2006) A checklist and bibliography of the Opisthobranchia (Mollusca: Gastropoda) of Victoria and the Bass Strait area, south-eastern Australia. Museum Victoria Science Reports 10: 1-42
- Coleman N. (2008) Nudibranchs Encyclopedia. Neville Coleman's Underwater Geographic Pty Ltd.
- Miller M. C. & Willan R. C. (1986) A review of the New Zealand arminacean nudibranchs. New Zealand Journal of Zoology, Vol. 13: 377-408
- Willan R. C. (1998) Suborder Arminina Pp 1009-1010 in Beesley, P.L., Ross, G.J.B. & Wells, A. (eds) Mollusca: The Southern Synthesis. Fauna of Australia. Vol. 5. CSIRO Publishing : Melbourne, Part B.
- Willan R. C. (2001) & Rudman, W.B. (2006) Janolus eximius, Factsheet & related messages. The Sea Slug Forum, Australian Museum, Sydney.

Dave Mullins
Queensland, Australia
February 2015
Send Dave email at marineimages@hotmail.com

WEBMASTER'S NOTES: Dave has been active in underwater photography since the early 70's and is presently the Webmaster/Publisher of Insights , a web site you definitely should put on your list of sites to visit!

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