Dear Sandrine et Hugues,

This is an interesting find. It certainly seems this species can have orange and black marks around the mantle edge as can be clearly seen in the animal you mention from Pemba.

The presence of both a grey and a red sponge in your photos is also rather tantalising as either - or both - could be the food of this species. Chromodoris boucheti belongs to a group of similarly coloured species of Chromodoris some of which eat both a red species of Negombata and some dark grey thorectid sponges. The light grey sponge in your photo looks like a dysideid. Species of Chromodoris don't usually feed on sponges of that family but there are a few species with black lines which seem to prefer them. So it would not be unreasonable to find C. boucheti feeding on either of the sponges in your photo. If you have any other photos of it associated with either of these sponges or the dark grey thorectid in the Pemba message [#16373], I would be very interested. By coincidence, there is another photo from Pemba [#16384] showing C. boucheti associated with a light grey Dysidea probably identical to the one in your photos.

Best wishes,
Bill Rudman

Dear Bob,
Thanks for the extra photos. Firstly, in your upper photo the left one is obviously C. willani but I am pretty sure the right one is not one of the colour forms of C. dianae. As I said in my earlier comments, the lack of a white speckled mantle [see insets comparing C. willani (left) and C. ? (right)]  makes me pretty sure this is C. boucheti. Also in C. dianae the yellow colour on the gills is confined to the upper half [see Roberto Sozzani's photo (message #15230) showing both these features].  Another difference between C. dianae and C. boucheti is more difficult to quantify, but C. boucheti and C. lochi are more elongate in shape, with a narrower mantle skirt than either of the colour forms of C. dianae. I guess we will never be sure now, but on balance I am pretty sure it is C. boucheti.

The photo alongside is a form of C. lochi with pinkish gills and rhinophores. The greyish colony it is on, with whitish spots, seems to be an ascidian colony rather than a sponge. This ascidian seems to have partially overgrown a sponge colony, which is probably what the chromodorids are feeding on.
Best wishes,
Bill Rudman

Dear Bob,

This is a useful message to get just after I posted Peter Southwood's photo of mating? Polycera capensis and P. chilluna [message #19387]. In my comments to that message I may have sounded a bit pedantic in saying that the animals were not actually mating although both had their mating apparatus fully extended. I explained that closely related species, seemed to participate in preliminary mating behaviour, when they were close to each other,  but did not complete the mating once contact had been made. It seems their chemical signals are very similar, but once actual contact is made each species can recognise its own kind - even from close relatives. I suspect this photo is an example of that. The one with white-spotted gills is C. willani, as you thought, and the other one looks a bit like C. dianae, but I don't think it is. One form of C. dianae has the upper half of the gills bright yellow, but in that species there are very distinctive white spots [glands?] all over the mantle, like in the photo of C. willani. There is no sign of these spots in this animal. In many ways it looks like C. lochi, but the way the orange colour on the gills stops above the base does not occur in C. lochi.

An interesting possibility is that this is C. boucheti, which has a median black line down the inside of each gill, near the base. If you look at the lower left close-up, there are traces of black at the base of the orange on each gill. Chromodoris boucheti has normally been found only in the western Indian Ocean but we have a record on the Forum from the Maldives Islands [message #11895] and a possible record from Sulawesi [message #5982] so your animal may be the third from the eastern Indian Ocean.

The animals seem to be on a weedy rock, but if you look at the underlying background it is a dark gray sponge which I am pretty sure is Petrosaspongia sp which is the food chosen by C. dianae, C. willani, and C. lochi. We have a  record of C. boucheti feeding on a sponge of the same family, so this could be a useful addition to our knowledge of its feeding specificity. If you have other photos of this C. boucheti, showing the gills from a different angle, I would be interested. I suspect the aggregation of similar animals like this is the result of them all preferring this food sponge. For completeness, perhaps you could send a photo of the C. lochi as well, and any photos showing more of the sponge.

Best wishes,
Bill Rudman

Dear Pasquale,
No this is C. boucheti. If the yellow edged one turns out to be different them it will need the new name not your one. However I think the black lines on the gills - both on the inside and outside edges - are a pretty good indicator of this species. We know little about this species so finding new things about its colour variation is always to be expected.

Concerning the sponge. It's always possible it is feeding on this sponge, but it looks in this photo to be crawling over the top of the colony rather than settling down to feed. I could be quite wrong so if you have any other photos of it or its kind on this sponge, or any other sponge for that matter,  I would be interested in seeing them.
Best wishes,
Bill Rudman

Dear Rob,

I haven't seen one with the yellow around the mantle ledge like this, but I am sure it is C. boucheti. The black lines on the gills seem to be a good character. I am very interested in the dark grey sponge in your photo which I suspect may be this species' food. Have you any more photos of this species from Pemba showing it on sponges? For that matter have you any photos showing the C. quadricolor and C. hamiltoni in your other message [#16372] being even slightly interested in any sponges?

Best wishes,
Bill Rudman

Dear Colin,
I guess the golden rule is that if you find something which doesn't fit the book, then the book may be wrong. We know so little about these animals that books are only as good as the information available when the book was written. One of the values of the Forum is that it is allows us to gradually build up new information as it becomes available. The depth range given for a species is really the 'known' depth range so increases to the range are always possible and always welcome. Certainly the small black line on the gills in the upper photo suggests it is C. boucheti, and I would agree that finding a more typical 'friend' at the same site is also very suggestive that it is that species. Chromodoris lochi never has opaque yellow pigment like this on its gills, although it can have a translucent yellow tinge at times. At present I am pretty sure there are no convincing records of C. lochi from the western Indian Ocean
Best wishes,
Bill Rudman

Thanks Fredy,
A useful addition to our knowledge of the species. I suspect the greyish sponge it is crawling on may be its food but it is so overgrown with algae etc that I don't think it will be possible to identify it.
Best wishes,
Bill Rudman

Thanks Marina,
It's good to get some more photos of this species. And thanks for the close-ups of the gills which show how it diifers from C. willani and C. lochi. Neither of those species have a black line up the inner and outer edge of each gill, and neither have a yellow tip.
Best wishes
Bill Rudman

Dear Paul,
Thanks for these nice photos of Chromdoris boucheti which is another species found only in the Indian Ocean. The gills, with their yellow tips, and a black line up the bottom half of both the inner and outer edges, differentiates this species from other similarly coloured chromodorids with black lines on a bluish-white background.
best wishes,
Bill Rudman

Dear Lindsay,
I think this is probably C. boucheti which has a yellowish rhinophore clubs and yellow-tipped gills, with a black line up the inside edge of the rachis. Its hard to be sure about the gill colouration in your photo but there are clearly signs of yellow and black. If it is C. boucheti, it is further east than its been reported before.
Best wishes,
Bill Rudman

Thanks Bernard,
It's nice to get further information on what parts of these colour patterns are consistent and which parts are variable. It's also interesting to hear about the sand encrusted sponge food (upper right, lower right photos).

Hypselodoris bennetti feeds on a sand-encrusted sponge like this. For a long time we didn't know what it ate - it was never seen near a 'real' sponge, until someone realised the 'substrate' was in fact a sponge, covered in algae, hydroids etc, but still a sponge.
Best wishes,
Bill Rudman

Dear Jim,
It's nice to get confirmation of its presence in the Maldives. This is quite tricky to sepaarate from Chromodoris lochi when you haven't got a good view of the black line on the inner edge of the gills.
Best wishes,
Bill Rudman

Dear Valda,
Another interesting, if not unexpected find. This is Chromodoris boucheti which I described some years ago from the western Indian Ocean. It is very similar in colour to C. lochi and C. willani which I distinguish from each other at the top of the page.

it would be interesting with some of your common species to see if they are found regularly on a particular sponge and if so taking a photo of them on the sponge. Knowing the preferred food and the shape and nature of their egg ribbon are two bits of information that can be very useful clues to whether two very similarly coloured animals are the same species or two different species.

Best wishes,
Bill Rudman.