Hoff & Carlson, 1990
Previously known only from the Mariana Islands, but reported below from Sulawesi, Indonesia.
UPPER: 3.3mm; Guam, Bile, boat channel; 27 April 1990. LOWER: 3.2mm; Guam, Cocos Lagoon; 6 November 1971
PHOTOS: Clay Carlson.
This species was reported by Hoff & Carlson to be quite variable in colour, two extremes being illustrated here. They record over 700 specimens from the Mariana Island chain, the largest being 4.2mm long, but were unable to find it south of the island of Guam. See Lindsay Warren's message below, for a record from Indonesia.
• Hoff, PJ. & Carlson, CH. (1990). A new Runcinacea from the Mariana Islands (Gastropoda: Opisthobranchia). Venus, Japanese Journal of Malacology, 48(4): 263-269.
Rudman, W.B., 1999 (March 23) Ilbia mariana Hoff & Carlson, 1990. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/ilbimari
July 22, 2006
From: Yuji Fujie
Concerning message #16226:
Locality: Obyan Beach, 5m, Saipan, Northern Mariana Islands, Pacific Ocean, 7 June 2006, under the dead coral. Length: 1mm. Photographer: Yuji Fujie.
email@example.comYuji Fujie, 2006 (Jul 22) Ilbia mariana in an ascidian. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/17149
Certainly in colour these animals inside the ascidian wall look like juvenile Ilbia marina but they seem to have thin orange, forked, structures coming out of the front (or back?) of the black section. Did you actually take one of these things out of the ascidian and have a look at it?
Nothing's impossible, but Ilbia is a herbivore, so it is a strange place to find it in large numbers like this. Unless you actually looked at one out of the ascidian, I would be inclined to think this was some sort of parasite, or worm. I look forward to your comments
April 3, 2006
From: Clay Carlson
Concerning message #16226:
Just a tad more info to go with the rush of material on Ilbia mariana. [it sure would have been nice to have had photos of this quality to work with 40 years ago]. In our database, through 2003, I. mariana is recorded 718 times: plus, 'A' [abundant] occurs 10 times. The largest measured specimen was 4.3mm, the smallest 1.5. The average of 53 measured specimens was 2.8mm.
The last 'A' record was from Gachogna Beach, Tinian; Jan. 1999.
Clay & Patty Jo,
Mariana Islands, Western Pacific
firstname.lastname@example.orgClay & Patty Jo, 2006 (Apr 3) Re: A juvenile Ilbia mariana ?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16233
April 3, 2006
From: Yukari Tani
Hafa Adai Dr.Bill,
I've found five very cute animals at the same place. Could you tell me if they are juvenile Ilbia mariana?
Locality: Shikatsuno-sango, 2m, Saipan, Northern Mariana Islands, Pacific Ocean, 02 April 2006, in the seaweeds. Length: 1mm. Photographer: Yukari Tani.
Si Yu'us Ma'ase !
Yukari Tani, 2006 (Apr 3) A juvenile Ilbia mariana ?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16226
Thanks for these photos of your very small animals. They are Ilbia mariana, and from their size they may be juveniles, but some of these species mature and mate at quite a small size so you can't really judge if they are 'juvenile' - in the sense of being 'immature' - just through size. I am also pretty sure this is not a juvenile colour pattern as Hoff & Carlson (1990), in their description of this species, describe 4 specimens from Guam which had a colour pattern almost identical to yours. Their animals had more black on the 'tail' but they also had the large black patch on the back. It must be the time for this species in the Nthn Marianas.
April 1, 2006
From: Takao Uraswa
Dear Dr Rudman
Thank you for your welcome advice every time.
I think this is Ilbia mariana Hoff & Carlson, 1990. What do you think?
Locality: Laulau Beach, 6m, Saipan, Northern Mariana Islands, Pacific Ocean, 30 March 2006, Coral gravel back. Length: 2-3 mm. Photographer: Takao Urasawa
email@example.comTakao Urasawa, 2006 (Apr 1) llbia mariana from Northern Mariana Islands. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16215
Yes this must surely be I. mariana. The colour pattern is very distinctive. There are very few records of this species every new one is very welcome
December 3, 2001
From: Scott Johnson
Not a very clear photo, but this looks like Ilbia mariana. It measured about 3mm and was found recently at Kwajalein, Marshall Islands.
firstname.lastname@example.orgJohnson, S., 2001 (Dec 3) Ilbia mariana from the Marshall Islands. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5770
March 23, 1999
From: Lindsay Warren
Please find attached another opisthobranch found in the Tukang Besi Islands [Sulawesi, Indonesia - Operation Wallacea] last year:
Length: 3 mm. Found at a depth of 5 m on dead branching coral covered in algae and tunicates. Initial thoughts are that it might be an Ilbia or Pseudoilbia. Overall the notum was white with yellow spots although parts of it near the mantle edge were transparent without any pigmentation as was part of the foot. Posterior mantle distinctly separate from tail. No rhinophores or gills visible. Two very noticeable black eye spots and behind these a 'butterfly' section with no pigment but bears clustered black spots. Square anterior head shield.
email@example.comWarren, L., 1999 (Mar 23) 'runcinid' from Sulawesi, Indonesia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/693
From the field sketches you have sent me it is almost certainly a runcinid or a related ilbiid, such as Ilbia.
It would be interesting to know if the black "eyes" are really eyes or just colour spots which look like eyes. Opisthobranch eyes are seldom as prominent as that, and in runcinids are usually only visible through the side of the body.
Bill Rudman.Rudman, W.B., 1999 (Mar 23). Comment on 'runcinid' from Sulawesi, Indonesia by Lindsay Warren. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/693
March 23, 1999
From: Clay Carlson
It looks like Lindsay's runcinid is Ilbia (or Pseudoilbia) mariana Hoff & Carlson, 1990. Don't know what it is doing so far from home.
UPPER PHOTO: 3.3mm; Guam, Bile, boat Channel; 27 April 1990. LOWER PHOTO: 3.2mm; Guam, Cocos Lagoon; 6 November 1971.
The species can vary quite a bit in color. I think we sent some color (colour) prints with the reprint we sent you. I can't get decent scans of the two darker variations.
firstname.lastname@example.orgCarlson, C. & Hoff, P.J., 1999 (Mar 23) Sulawesi runcinid is Ilbia mariana. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/718
Thanks again. I'm afraid I looked at your 2 colour prints of the dark colour form and didn't connect them with Lindsay's animal. Once I got your message and checked your reprint it is very clear that the Sulawesi animal is your Ilbia mariana. I'll see if I can scan your colour print.