Janolus capensis from False Bay, Sth Africa
June 23, 2005
From: Wilhelm van Zyl
Hi Bill
Concerning your comments about the other animal [#14092 ]:
It was actually this ridge or absence thereof that made me think it was Bonisa. I cannot see any ridge between the rhinophores in that picture. On my next dive I will specifically look for this. Another thing that made me wonder was the shape of the cerata, they are more club shaped than the other Janolus specimens I have.
I do not know if this can be used to differentiate between the 2. I am sending you my best photo of Janolus capensis to date. I took it on a dive site called Castle Rock near Simons Town in False Bay at about 5m water depth. Although you cannot see the ridge I am sure this is Janolus.
Regards
Wilhelm
diving@cyberdale.co.za
van Zyl, W., 2005 (Jun 23) Janolus capensis from False Bay, Sth Africa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14114Dear Wilhelm,
The large caruncle between the rhinophores is probably the best bet but as you can't see that in many photos it doesn't help much. I don't think how flattened the cerata are is a good thing to use as their shape is fairly plastic. One very important feature though is whether there is a branch of the digestive gland in the cerata. There is branch in species of Janolus, but not in species of Bonisa. In your photo here the reedish-brown branch, which forks near the tip is quite visible.
Best wishes,
Bill Rudman
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