Janolus sp. 6
Order: NUDIBRANCHIA
Suborder: ARMININA
Family: Zephyrinidae
DISTRIBUTION
New Zealand & southern Australia
PHOTO
Poor Knights Ids, [NE New Zealand] about 200 metres north of entrance to Riko Riko, 19 May 1999. Approx 7-10 metres. Length about 8-10mm. Photos: Andrew Green
RELATED TOPIC
Miller & Willan (1986) identify this species with the North Atlantic species Janolus hyalinus, suggesting it arrived in Australian and NZ waters artificially. As I discuss below I find it difficult to reconcile the differences in colour and the fact that the digestive gland of the Australasian species runs to the ceratal tip, with the 'typical' Atlantic form. In the Forum this species has a confused history having been previously named Janolus cf. novozealandicus and Janolus cf. hyalinus. See discussion by Rudman and Willan below. See also Bernard Picton's message. See also Richard Willan's message agreeing that this is not J. hyalinus.
Reference:
• 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.
Rudman, W.B., 2001 (June 8) Janolus sp. 6 [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/janosp6
Related messages
Re: Andrew Green's Janolus cf. novozealandicus
June 10, 2001
From: Richard Willan
Dear Bill,
Andrew Green's animal animal from New Zealand which you tentatively associated with Janolus novozealandicus is what Michael Miller and I (1986) identified as Janolus hyalinus. J. hyalinus is a European species, that we believe has been introduced by shipping into both temperate Australia and New Zealand. It is essentially a golden or brown species (no white patches on the body, or blue or gold rings on the cerata). The cerata of J. hyalinus are very pustulose, and it will cast them off at the slightest touch. J. hyalinus seems to be commoner in Victoria than New Zealand, so it is a case of “Murphy’s Law” that Andrew Green’s records of adults from New Zealand made it onto the Forum first; the name used there for it “Janolus cf. novozealandicus” needs to be changed to J. hyalinus.
References:
• Willan, R.C. & Coleman, N. (1984) Nudibranchs of Australasia. Australasian Marine Photographic Index, Caringbah, Sydney, 56 pp.
• 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.
Richard Willan
Richard.Willan@nt.gov.au
Willan, R.C., 2001 (Jun 10) Re: Andrew Green's Janolus cf. novozealandicus. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4542Dear Richard,
I have a bit of a problem with your identification of this animal with the European Janolus hyalinus. I have discussed this with Michael Miller and must admit I am in the minority, with him in total agrement with you. What I find difficult is that you, and European workers characterise J. hyalinus as having the digestive gland duct running only halfway up the cerata while in Andrew Green's photos the NZ one defintiely has a digestive gland which runs to the ceratal tip. The European species is also a uniform golden brown whereas the NZ one has quite a colouful pattern.
I may be quite wrong, but its taken me hours to untangle the Janolus cf. novozealandicus messages on the Forum so I think it is prudent, for editorial reasons, to leave this animal on a separate page as Janolus cf. hyalinus until we are quite sure.
best wishes,
Bill Rudman
Janolus cf. novozealandicus from New Zealand
May 23, 2001
From: Andrew Green
Bill,
Phil Bendle from Norseman Charters at Tutukaka, NZ gave me your website address. Here is a photo of an unidentified nudibranch.
Location: Poor Knights Ids, [NE New Zealand] about 200 metres north of entrance to Riko Riko, site known locally as "The Garden", taken at night, 19/5/99. Estimated
depth: 7-10 metres. taken with micro-nikkor at 1:1. Length of nudibranchs about 8-10mm.
Would appreciate advice of ID some time, when you have time. I am about to head back there in 2 weeks, for annual week long charter with Phil (6th trip). I have some other odd nudis from earlier trips if you are interested.
Regards,
Andrew Green
agreen@acr.net.au
Dear Andrew,
Thanks for the photo of this interesting species. The two animals are apparently feeding on the red arborescent bryozoan which I would tentatively identify as Orthoscuticella cf. margaritacea. It is almost certainly a species of Janolus. New Zealand members of this group were reviewed quite recently by Miller & Willan (1986), but your animal doesn't fit the known species very well. It seems that the cerata in these animals are somewhat variable in shape sometimes long and slender, and at other times more like in your photo.
The only species yours seem to resemble is Janolus novozealandicus. We recently were sent photos of a similar looking animal from Victoria, Australia. One distinctive feature of both your animal and the Victorian one is the tubercles on the cerata, which Miller & Willan say occur in both J. novozealandicus and the apparently introduced species Janolus hyalinus. In your lower right photo you can see the dark brown digestive gland duct passing right to the tip of each ceras. Miller & Willan say that is characteristic of J. novozealandicus. In J. hyalinus the duct stops about halfway up the ceras. I am not sure if these animals are the same species or if either is J. novozealandicus so for the moment I am putting them together on a Janolus cf. novozealandicus Page.
Hopefully Richard Willan or Michael Miller can offer their views
Best wishes,
Bill Rudman
Janolus hyalinus? from Victoria, Australia
April 30, 2001
From: John Chuk
Dear Bill,
Here are photo's of another Janolus species from Portsea Pier, Victoria, Australia. I suspect that this one is Janolus hyalinus but I would be keen to have your opinion on this ID. The specimen was photographed on a night dive on 19 March 2001. It is 18mm in length and was found crawling on brown algae at a depth of 4.5m.
The specimen has inflated, papillose cerata. The cerata appear translucent with some brown mottling and are covered in minute white spots. A dark extension of the digestive gland could be seen extending into the cerata for about half their length.
The rhinophores are lamellate and are closely placed, separated only by an obvious sensory caruncle. This can be seen in one of the views.
Best Wishes,
John
jchuk@giant.net.au
Chuk, J., 2001 (Apr 30) Janolus hyalinus? from Victoria, Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4252Dear John,
From external appearance I think this is the animal that Burn and subsequent authors have recorded from Victoria as J. hyalinus. It certainly looks like the European species. This certainly suggests that the animal in your earlier photo was not J. hyalinus. I still suspect it is probably the species, previously known only from New Zealand Janolus novozealandicus.
best wishes,
Bill Rudman
