Dear Francis & Pirjo,

This is a nice find. Yes I agree its H. sagamiensis which is very interesting because it provides a link between what we thought was the "home range" of this species in the Sino-Japanese region of the north Pacific and the large populations Gary Cobb [#19421] has reported from southern Queensland in eastern Australia. It looks like this species, rather than being endemic to the north-eastern Pacific has a wider distribution at least in the tropical western Pacific. As I discuss in Gary Cobb's message, this has an interesting similarity to the way the distribution of H. maritima , which was initially considered a Japanese endemic, was extended firstly to eastern Australia and then the intervening region was gradually filled in.

Concerning the juvenile. With the usual hesitation in identifying juveniles, I am pretty sure this is also H. maritima.

Thanks also for the sponge photo. Dark coloured sponges are always a problem to interpret from photos as much of the detail is lost in the shadows. It certainly could be a species of Euryspongia but I can't be sure. While concentrating on the detail, I almost missed the whitish mass on the right side of your feeding photo. As you can see in the close-up, it is the fibrous skeleton of a dysideid sponge - probably the same as the one the Hypselodoris is eating. Although I can't be sure, it seems reasonable to assume that this slug has eaten the first bit and has now moved on to the next bit - they may both be parts of the same colony. I think we can make a tentative determination that this species feeds on a dysideid sponge, possibly Euryspongia sp. This is the first indication we have of the feeding choice of this species.

I have also ringed a white spot on the edge of the mantle [middle photo]. This is one of the mantle glands which store distasteful chemicals from their sponge prey. In species of Hypselodoris and closely related genera the mantle glands are like this - discrete spherical or ovate sacs, quite different from the dendritic glands found in species of Chromodoris.

Best wishes,
Bill Rudman

Dear Bruce,
Thanks for letting me know. I am afraid I must get in a confused state when  H. rudmani is mentioned. I think of H. sagamiensis as a 'black-spotted' species so it didn't enter my list of possibilities when I tried to identify your animal, but I am sure Richard is correct. This is apparently a colour variant in which black spots are absent except for a very few near the mantle edge. It also lacks most blue spots down each side of the mantle. But the opaque white bumps all over the mantle and the other elements of the colour pattern are the same as in Gary Cobb's recent specimens [#19421] from southern Queensland.

I'm glad we have that sorted out
Best wishes,
Bill Rudman

Note added 5 June 2007: This is H. sagamiensis see message #19985.

Dear Bruce,

I'll do the easy bit first - yes the little bubble shell is a juvenile Bullina lineata.

As to the Hypselodoris. I feel a bit of failure not being able to identify a species named after me with certainty, but I would hesitate to say that this is H. rudmani - but then again it definitely has similarities to the animal in Colin's message which you refer to. H. rudmani was described from the NE coast of South Africa so it most probably has a wider distribution in at least the Indian Ocean. Perhaps Terry Gosliner or Rebecca Johnson could give us their opinion.

Best wishes,
Bill Rudman

Thanks Gary,

I was 'up to speed' on your finds of H. sagamiensis in southern Queensland, from your book, but I needed a photo or message to add it to the Forum. I wish I had time to search all the other excellent websites to pick up new distribution records but as you no doubt realise, I don't. When I said it was only known from the north west Pacific I was thinking in terms of what I was considering to be its 'natural' distribution.

The presence of H. sagamiensis in eastern Australia is interesting in itself, and it reminds me of H. maritima, which for a long time was known only from Japan and eastern Australia. As I mentioned recently [message #18625]  there was some thought that its presence in Australia was due to shipping, but we now have a number of records from places in between, suggesting it may be naturally found all through the western Pacific. At present H. sagamiensis seems to have a similar distribution in the north west Pacific and eastern Australia. It will be interesting to see if it begins to turn up in the tropical Pacific between these two regions.

Another equally interesting possibility is that H. sagamiensis is a colour form of H. maritima. Much of the basic pattern of the two species is the same, the main difference being that the longitudinal lines in H. maritima are replaced by spots in H. sagamiensis. However if we look at an earlier message from Erwin Koehler [#13910], it seems that H. maritima can have black spots instead of lines.

Thanks for sending the photos, they certainly reminded me of your find, and hopefully they have opened up an interesting line of investigation
Best wishes,
Bill Rudman

Dear Rick,
Your animal has similarities to H. infucata but I am pretty sure it is the Japanese species Hypselodoris sagamiensis. I won't even try and explain how it ended up in a UK aquarium, but allowing for a bit of overexposure in your photo I am pretty sure this is what it is.

Best wishes,
Bill Rudman

Dear Nishina,
I separated these photos from your message about Hypselodoris maritima as these are the similarly coloured species Hypselodoris sagamiensis. Can you confirm these are its egg ribbons?
Best wishes,
Bill Rudman

Dear Nishina,
Thanks for these photos. I think I have only seen a couple of photos of H. sagamiensis before. This species is very interesting in having quite strongly developed pustules on the mantle, which is unusual in the family Chromodorididae. Another unusual feature is that no-one has found mantle glands in this species. In species of Hypselodoris the mantle glands are usually small sacs around the mantle edge, and in many species they become much larger and numerous around the posterior end of the mantle.

Best wishes,
Bill Rudman