Tropical Indo-West Pacific (Japan, Palau, Papua New Guinea, Queensland, Madagascar)
Kerama Island, near Okinawa, Japan. PHOTO: Atsushi Ono. See message below.
It is characterised by the pattern of orange stripes. Length 3-4mm. Gosliner reports this species to be the most abundant gastropterid in Madang, Papua New Guinea, where it is found in the undersurface of coral rubble, on shallow reefs. According to Gosliner it has never been observed swimming.
• Gosliner,T.M. (1989): Revision of the Gastropteridae (Opisthobranchia: Cephalaspidea) with descriptions of a new genus and six new species. The Veliger, 32(4): 333-381.
• Ono, A. (1999) Opisthobranchs of Kerama Islands. Tokyo: TBS-Britannica Co.
Rudman, W.B., 1999 (July 29) Siphopteron tigrinum Gosliner, 1989. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/siphtigr
November 16, 2006
From: C.Carlson & P.J. Hoff
Concerning message #18348:
We think Yuji's animals are probably S. citrinum. It would be nice to find some S. tigrinum in the Marianas but so far we have had no luck. I have attached a sample of S. citrinum from the back yard. The body can be solid yellow, or all pink --generally found as a mixture of the two; the pink being the underlying color.
An example of S. tigrinum from Palau is also included for comparison. Afraid neither of the slides is of recent vintage.
Upper photo: Siphopteron citrinum (Carlson & Hoff, 1974), 3.2 mm; Guam, Bile Bay, 26 March 1970. Photographer: Carlson & Hoff
Lower photo: Siphopteron tigrinum Gosliner, 1989; 4.0 mm; Palau, Ngkesill, reef flat; 6 August 1978. Photographer: Carlson & Hoff
Clay & Patty Jo
email@example.comCarlson, C. & Hoff, P.J., 2006 (Nov 16) Siphopteron tigrinum or Siphopteron citrinum?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18364
Thanks for your comments. I had begun to wonder whether these two species were colour forms of the one species, but on reading your original description I didn't realise the pink you mentioned was this background colour. My feeling is that S. tigrinum must be a colour form of S. citrinum. There is certainly nothing in what we know of the anatomy of the two 'species' to think they were different. I would appreciate your views on the other animals on the Forum which I have identified as S. tigrinum. Would you consider the spotted ones to be S. citrinum? If so I can't see why the yellow-lined ones aren't also that species. The only real colour difference is that in S. tigrinum there is a thin dark bluish line separating the yellow and the pale pink? or bluish? regions.
I am happy to identify them as S. citrinum but I suspect if I do that I may as well remove the S. tigrinum page. What do you think?
- Carlson, C. H. and Hoff, P. J. (1974) The Gastropteridae of Guam. with descriptions of four new species (Opisthobranchia: Cephalaspidea). Publications of the Seto Marine Biological Laboratory 21: 345-363.
November 15, 2006
From: Yuji Fujie
Following my last message [#18347], I attach 3 photos of Siphopteron tigrinum mating.
Locality: Laulau Beach, 8 m, Saipan, Northern Mariana Islands, Pacific Ocean, 7 April 2006, on the dead coral. Length: 3 mm. Photographer: Yuji Fujie.
Sorry for the poor pictures.
firstname.lastname@example.orgYuji Fujie, 2006 (Nov 15) Re: Siphopteron tigrinum mating. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18348
Considering the size of the animals I don't think you need to apologise about the quality of the photos - I think its amazing that you got any photos at all.
Like all cephalaspideans, the penis is on the right side of the head and the female genital opening is on the right side near the posterior end of the body. This leads to many cephalaspideans mating in a head to tail position. However this is not always the case and in your upper photo the upper animal (which acting as the male) has approached from the right side, and I am pretty sure I can see the long inflated, almost transparent, penis lying across the open parapodial 'wing' and entering the female genital opening which is under the front part of the visceral hump.
November 15, 2006
From: Yuji Fujie
Concerning message #6427:
I think this is Siphopteron citrinum. This animal is very common in Saipan.
We did not see any over 4 mm in length.
Locality: Laulau Beach, 6 m, Saipan, Northern Mariana Islands, Pacific Ocean, 6 June 2006, on the dead coral. Length: 2 mm. Photographer: Yuji Fujie.
email@example.comYuji Fujie, 2006 (Nov 15) Re: Siphopteron tigrinum from nthn Mariana Islands. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/18347
This is an interesting find. I suspect this is a spotted form of Siphopteron tigrinum. In this species the yellow markings are usually broad bands rtaher than the large spots of your animals, but in general shape and purplish background colour they are the same.
The external colour of Siphopteron citrinum (Carlson & Hoff, 1974) seems to be known only from the original description. The animal is similar in shape, but the background colour seems to be a uniform yellow. I guess more specimens willl need to be studied before we can say whether it is always uniform yellow in colour or not.
In a message yesterday [#18337] about Siphopteron michaeli I discussed the shape of the 'siphon' in species of this genus. Your photos show the median crest on the enrolled siphon very well. The crest extends beyond the end of the siphon as a black rod.
June 15, 2001
From: Erwin Köhler
here is the first one of my recent trip to the Philippines, Cebu Island, Moalboal. It looks to me like Siphopteron tigrinum, but it can be something else as well. I found it upon a dead Acropora sp. coral at 4 m depth on May 27, 2001, divesite "Dolphin House". One photo shows the tip of my forefinger, so you can see it was pretty small, I guess 2-3 mm.
Köhler, E., 2001 (Jun 15) Siphopteron tigrinum? from the Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4544
Yes this is Siphopteron tigrinum, and yes they are usually pretty small.
August 6, 2000
From: Kazuko Matsuda
These were found quite near to the place where I found the other species of Siphopteron on the same day. They were rotating clockwise slowly.
Data: 23 July 2000, 4mm long, 16m depth
Sunabe in Okinawa, Japan
firstname.lastname@example.orgMatsuda, K., 2000 (Aug 6) A mating pair of Siphopteron tigrinum. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2839
Thanks very much
July 30, 1999
From: Atsushi Ono
Attached is the photo you requested.
S.tigrinum is rare on Kerama Is,near Okinawa. I have seen only 5 individuals in the last 3 years.
We can find it from 3-10m depth, but size is very small 3mm long. I think that they are seen all the year round.
email@example.comOno, A., 1999 (Jul 30) Siphopteron tigrinum from Kerama Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1136
Again thanks for the photo. Your side views of the very small animals give us a very good idea of the shape of these amazing animals.