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Geitodoris planata

(Alder & Hancock, 1846)


Tony Gilbert Whilst visiting St. Abbs a couple of weeks back we were unfortunate to be cancelled off Pete Gibson's on our last day owing to the incessant ground swell that has plagued this area for a few weeks now. So rather than mope around, we (and a few others) went into Loch Long on the west coast. I was pleasantly surprised when I spotted this Geitodoris planata which isn't seen that often. It was right next to a long rope just off Tighness boat slip in 12m, great dive!

Message posted on NE Atlantic Nudibranchs on 20 Jun 2012
David Fenwick Snr Geitodoris planata have been very common this year in Mounts Bay and we've even found them mating in the past week or two. Today we found three egg masses and wondered if they could be attributed to this species.

Message posted on NE Atlantic Nudibranchs on 10 Apr 2012
Arie Vreugdenhil Geitodoris planata 7 cm large animal at 5m in the "Oosterschelde" the Netherlands. Wasn't seen here for 2 years, after an explosive appearance in 2000.

Kiki Vleeschouwers Geitodoris planata in the Oosterschelde, the Netherlands

Message posted on NUDIBRANCH LOVERS on 01 Jun 2013
Philippe Velghe Extraterrestrial creatures exist, they call Geitodoris Planata. Enjoy :-)

Message posted on UWphotographers on 11 May 2013
George Brown A couple of Geitodoris planata, enjoying some sponge, on Aequipecten opercularis. Can anyone help me with the sponge ID please? Loch Creran, 13 steps, 20m depth, nice dive.

Jade Berman Mycale macilenta maybe? Beautiful picture

Bernard Picton You've a good eye, Jade. I call this Mycale cf. macilenta because the ones on Aequipecten in Strangford Lough had some small spicule differences to the Mycale macilenta in other habitats in the Lough. It is hard to find in Strangford now as the Aequipecten seem to have gone extinct. There were plenty of big ones even after the Modiolus reefs were trashed but I suspect that the massive ecological consequences of that fishery changed things in a way that has now stopped recruitment or increased predation on juveniles.

George Brown Thank you Jade and Bernard, not just for the ID but for the background information sad though it is. I recently gave a talk to the Highland Biodiversity Forum, taking the opportunity to criticise scallop dredging, especially inshore. The forum is sponsored by the local authority, The Highland Council. This has resulted in the Council asking for more information on the effects of dredging and I've been asked for more photos/video of before/after dredging has been carried out. In an effort to maximise this opportunity do you know of any photos or video I can show our Councillors? I have nothing showing physical damage. Please be in no doubt that much of the Highland seabed has been totally devastated by bottom dredging. Thanks again for the ID.

David Kipling Hasn't Joanne Porter and colleagues got a recent paper on direct before/after effects of trawling through a Modiolus bed?

George Brown Thanks David, I'm on the case!

Becky Hitchin Yes, David Kipling, its a very good paper too

Becky Hitchin Robert Cook and colleagues in this study describe the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfishreefs formed by the horse mussel Modiolus modiolus (L.). One of the study sites was trawled and the other was scallopdredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site. The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90%) or scallop dredge (59%), as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids) were recorded in the trawl track. To read more go to: http://www.plosone.org/article/fetchObject.action?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0069904&representation=PDF

George Brown Thank you Becky.

Bernard Picton The critical thing to mention is the fact that the NI fisheries and environment agencies have already spent over £1 million trying to restore the habitat in Strangford Lough because the EU will start to fine them if it is not restored to a favourable status. As the habitat may have been established gradually over thousands of years and now the climate is changing it may not be possible to fix it.

Message posted on NE Atlantic Porifera on 25 Oct 2013
David Kipling One good deed deserves another? Here Geitodoris planata nudibranchs are keeping the top valve of a scallop clean of encrusting sponge. Loch Creran SAC in ~ 15m of water

Paula Lightfoot There are very few records of this species from the east coast - definitely none on the NBN Gateway although I know there are some from St Abbs on the Scottish Nudibranchs website. Two Yorkshire records have just been published in the YNU's journal The Naturalist, from Jackson's Bay Scarborough on 15th June 2010 and Burniston Bay on 10th May 2012.

David Kipling It was locally abundant in Creran - loads of scallops with encrusting sponge helps!

David Kipling I also wonder if it is under-recorded Paula - it does look a bit like Doris pseudoargus (bit flatter and more spread out) although the habitat gave it away.

David Kipling Two more examples from the same dive, better illustrating the "flat disc" appearance of this species compared to D. pseudoargus

David Kipling

David Kipling Paula - its distribution nicely mirrors that of one sponge suggested on Habitas as its food (Mycale rotalis) - although I think Bernard thought that the sponge on the scallops at Loch Creran was another (possibly undescribed) Mycale species. As always with nudis: find the food, find the nudi ...

Paula Lightfoot I know there are plenty of west coast records and that it is common in Loch Creran - well illustrated by your excellent photos and some similar ones on the Scottish Nudibranch website too. But just saying it would be nice to mobilise some of the east coast records onto the NBN Gateway :). This topic has come up a couple of times in the NE Atlantic Nudibranch Fb group too - with some excellent pics showing the diagnostic features (pale star shaped patches around acid glands and brown spots under the mantle if I remember right??) and some discussion about its various spongy food choices. I think it's mainly the younger specimens that can look similar to sea lemons.

David Kipling So where do those YNU records end up?

David Kipling As an underwater jizz thing, this species seemed to be flatter and more circular in shape than a sea lemon. It was certainly enough to make us think "eh? something's not right here" and take a photo.

Paula Lightfoot Records sent to YNU recorders or entered into our online recording website go onto the NBN Gateway in datasets administered by the relevant national recording scheme or local records centre - no problem. Our published data policy says that all records submitted will be shared publicly in this way so we don't need to get individual permission. At last year's AGM it was clarified and minuted that records included in articles sent to the journal are also covered by this data policy - in theory - the interesting thing will be whether that works in practice ;) Agree about the jizz, it looks like a sea lemon that's been squished. Lemon squash.

David Kipling * groan * :)

Bernard Picton This species was historically confined to the SW of the UK. It underwent a spectacular increase in the Netherlands after arriving there for the first time. It now seems to be doing well in Loch Creran. The sponge on the scallop is probably Mycale cf. contarenii, which used to be common on Aequipecten in Strangford Lough but is now almost extinct there after it was targeted in 1987-1989 by the Isle of Man fishing fleet and its nursery habitat of the Modiolus beds was almost destroyed. In the Netherlands I think it took advantage of the sponge Mycale micracanthoxea which itself was probably an aquaculture related introduction. What tangled webs we weave.....

Message posted on British Marine Mollusca on 15 Sep 2013
Erling Svensen The Geitodoris planata from yesterday. I saw hundreds yesterday, and many between the Ciona. When looking at the pictures, I can see eggs. Do anybody knows if these are Geitodoris eggs?

Brendan Oonk The eggs of G.planata are ribbon shaped. For foto see website of John de Jong http://electest.home.xs4all.nl/Biologie%20Oosterschelde%20en%20Grevelingen/Zeenaaktslakken/Geitodoris%20planata%20(Millennium%20Wratslak)/slides/DSC06813.html

Erling Svensen OK. Thanks. Then I do not have any clue what these eggs are.

Peter H van Bragt Are you shure they are eggs???? Could it be possible that we are looking at developing Diplosoma listerianum (Tunicates) colonies? Are tehre better/detailed pictures available. Geitodoris planata was first observed in the Netehrlands in 1999. Ar that time there was an abundance of Mycale micracanthoxea. The G. planata population developed very fast and in 2001-2003 we found on occasions up to 30-450 speciemn per dive (75 minutes). At that time the sponges where rapidly depleted by scavenging nudi's and subsequently in the next year the G. planata population collapsed almost completely. At this moment we only occasional find them back in very small numbers. The sponge population is recovering again due to lack of predation. We have observed that G. planata also seems to be sensitive to severe winters. Cheers Peter H. Peter H van Bragt

Message posted on NE Atlantic Nudibranchs on 21 Jun 2012
John de Jong Doris pseudoargus ?? at Zeelandbrug, Oosterschelde. 27-08-2012 with Olympus E330, 50mm macro, 1/100s, F18, ISO400 with 2x Ikelite DS160/161

Peter H van Bragt No, I think it is a Geitodoris planata just an uncommon colour variant. Cheers, Peter H van Bragt

Ian Smith Hi John I think this might be a pale Geitodoris planata. The tubercles seem a bit smaller than those on Archidoris, the mantle skirt is spread out nearly horizontal, there seem to be paler areas round large tubercles (acid producing on G. planata) . The clincher would be dark mars on underside of mantle. Oh, Peter has just beaten me and agrees. Have a look at the full description at http://www.conchsoc.org/spaccount/Geitodoris-planata Groetjes Ian Smith

John de Jong Thnx, Peter H van Bragt and Ian Smith. I thought I got a new one :-(

Ian Smith Location, location! I've never seen a live G. planata; the description was with photos and advice from Malcolm Storey who found the specimens shown on the web page. There were hundreds of of Archidoris pseudoargus spawning on a shore of the Menai Straits in Wales last March. Rhaid iddi ti ddo^d i Gymru (You must come to Wales :-) Ian Smith

Peter H van Bragt Hi Ian hop over the ditch. We do have them available in the southwestern estuary of the Netherlands. Although now less common as they used to be. In 2003 I had one dive with over 450 specimen and a max. size of 12 cm. Good old days ;-)

Ian Smith Hi Peter That's a big Geitodoris. I'll alter the Conch Soc account to allow for it. Ian

Tony Gilbert To me this looks like Archidoris psuedoargus. The colouration is that of a sea lemon, not G. planata which are usually brown. Check your images of this as G. planata has 10-12 stellate acid glands on the mantle, so your specimen needs these for id. Additionally, Bernards information indicates no records exist in the North Sea for this. The G. planata specimens I've seen have always been on west coasts. http://www.flickr.com/photos/tonyjgilbert-images/7501724518/in/set-72157630420768730

Ian Smith Hi Tony, have a look at http://www.diverosa.com/categories%20NL/ff%20naaktslakken.htm on it there are unmistakeable Geitodoris from East Scheldt estuary, branch of N.Sea. One is so low profile it looks like it's melted over the substrate. Another clearly shows the purplish peppering on the stem of the rhinophore. The tubercles are right for Geitodoris on these photos and on John's. Also Peter says he had 450 in one dive. Morphology is much more important than colour, but you can make out the pale acid papillae on John's specimen even though it is a pale specimen. The most decisive colour factor is to look for the dark marks on the under side of mantle and upper surface of foot on Geitodoris. Check out the conch soc description (link on my earlier message), it raises the possibility that Geitodoris is overlooked as A. pseudoargus in Britain. Cheers Ian

João Pedro Silva An example of a very flat G. planata: http://www.flickr.com/photos/jpsilva1971/6578495629/

John de Jong I will search him next week, and make some pics from the underside. First - have to find him ofcourse........

Ian Smith John I have just looked at Peter's excellent messages & photos about Oostschelde Geitodoris on the Sea slug forum: http://www.seaslugforum.net/find/5126 It seems from his photos that the dark marks, while present on the underside of the mantle and upper surface of foot of Dutch specimens, they may not be as heavily marked as on the British ones shown on the Conch Soc site. Cheers Ian

Ian Smith Joao have you any suggestions on how to separate Geitodoris planata from 'Doris' stellata, apart from radula dissection? I've seen several Mediterranean shots of slugs identified as stellata, but I find them difficult to distinguish on external appearance. Do you on the Atlantic-Med corner have experience of both species? Thanks if you can help. Ian

João Pedro Silva Ian, the only truly safe way to distinguish them is through the radula. But, at least aroung these parts, G. planata appears to show a more regular pattern on the mantle than Discodoris stellifera. Both show dark spots on the underside of the mantle. http://www.flickr.com/photos/jpsilva1971/6824858576/

Message posted on NE Atlantic Nudibranchs on 31 Aug 2012
Erling Svensen The Geitodoris planata from yesterday. I saw hundreds yesterday, and many between the Ciona. When looking at the pictures, I can see eggs. Do anybody knows if these are Geitodoris eggs?

Brendan Oonk The eggs of G.planata are ribbon shaped. For foto see website of John de Jong http://electest.home.xs4all.nl/Biologie%20Oosterschelde%20en%20Grevelingen/Zeenaaktslakken/Geitodoris%20planata%20(Millennium%20Wratslak)/slides/DSC06813.html

Erling Svensen OK. Thanks. Then I do not have any clue what these eggs are.

Peter H van Bragt Are you shure they are eggs???? Could it be possible that we are looking at developing Diplosoma listerianum (Tunicates) colonies? Are tehre better/detailed pictures available. Geitodoris planata was first observed in the Netehrlands in 1999. Ar that time there was an abundance of Mycale micracanthoxea. The G. planata population developed very fast and in 2001-2003 we found on occasions up to 30-450 speciemn per dive (75 minutes). At that time the sponges where rapidly depleted by scavenging nudi's and subsequently in the next year the G. planata population collapsed almost completely. At this moment we only occasional find them back in very small numbers. The sponge population is recovering again due to lack of predation. We have observed that G. planata also seems to be sensitive to severe winters. Cheers Peter H. Peter H van Bragt

Message posted on NE Atlantic Nudibranchs on 21 Jun 2012
Robert Eriksson

Robert Eriksson Following Erlings discussion below. Pale A. pseudoargus, G. planata... Or?!

Klas Malmberg Aquatilis I would say G. planata because o the starlike symetrical spots?

João Pedro Silva Here in Portugal we have another similar species, Discodoris stellifera, with the same star shaped marks. I agree this is most probably G. planata.

Bernard Picton Robert, yes, certainly this is Geitodoris planata. You are right, the mix of small and large tubercles is more or less the same as in Archidoris pseudoargus. The gills directed to the rear is very typical of Geitodoris. Joao, I'd love to hear how you distinguish Discodoris stellifera....

João Pedro Silva Bernard, in the next hour or so I'll be posting one of today's photos showing D. stellifera. I made a couple of photos to show the brown spots one the underside on the mantle edge and also showing the large oral tentacles.

João Pedro Silva Hmm, same in G. planata. Maybe we should check the radula? Anyway, we collected it.

Message posted on NE Atlantic Nudibranchs on 29 Feb 2012
Erling Svensen Could this flat nudy be a Jorunna tomentosa? Its on a rock with a litle silt on it. I saw some tiny J. tomentosa during the dive, but this one (if it is J. tomentosa) was aprox. 2 cm long.

Christian Skauge I don't think so... the Jorunna should have more spiky, almost hair-like tubercles - these seem more rounded. Could it be a juvenile Doris pseudoargus?

Robert Eriksson Look at the acid glands. I'd say a starved geitodoris planata because of the few "glands". They appear more round when not moving and therefore atypical compared to e.g. Thompson o brown 1984.

Bernard Picton I agree with Christian, I think Archidoris pseudoargus (can't bring myself to call them Doris yet!) The mixture of rounded smaller and larger tubercles is just right. I don't think those are acid glands, Robert, but I don't know what they are.

Peter H van Bragt Considering the mix of relatively large and smaller tubercles, I agree with Bernard. On few occasion we also found such pale individuals on the Dutch coast.

Robert Eriksson I am not convinced. I have one photo of what I regard a G. planata. There are several characters which are different from A. pseudoargus; bilamellate mantle for instanstance. Had a discussione with Jussi regarding this... se my obsolete opisthobranch webpage... http://web.comhem.se/~u93824250/ob/

Robert Eriksson I see that this one has crenulated edges round the rhinophores. My photo shows no such character - has anyone read the species description of G. planata and A pseudoargus lately? I would say that crenlutade edges is a very stabile trait, in contrary to "spots", "brown colour" or "flattened shape".

Message posted on NE Atlantic Nudibranchs on 28 Feb 2012
Jim Anderson Here's a double - Geitodoris planata on sponge covered 'upper' shell of Aequipecten opercularis> Loch Creran, Scotland - 26 may 2013

Sutherland Maciver Wow! quite a find!

Jim Anderson This is the 3rd time I've seen this combination and always at this location.

Sutherland Maciver Is the sponge Suberites luridus do you think? Its quite pale?

Sutherland Maciver it could be any number of sponges I suppose? Inculding Myxilla incrustans

Jim Anderson I'm not sure of sponges!

Sarah Bowen Not just a double; there's a tiny brittle star to the right of the nudi as well! Beautiful!

Paula Lightfoot ...which reminds me there are still no east coast records of this species on the NBN Gateway, so if anyone has any records from anywhere on the east coast (e.g. St Abbs) that they would like to share ... ;-)

Sutherland Maciver Yes I have photographed Geitodoris planate at St Abbs and know from Jim's Scottish Nudi pages that he has also

Sutherland Maciver planata sorry!

Paula Lightfoot These are diving records? If you send Dawn Watson the date, site name, coordinates (grid ref or lat/long) and depth range she can add it to the Seasearch data and it could be on the NBN Gateway within a month. We're sending an update to correct a few errors in the Seasearch dataset shortly so now's the time to add any extra records!

Message posted on British Marine Mollusca on 27 May 2013
René Weterings Geitodoris planata.....one of the "thousands" that can be found in the Eastern Scheldt at the moment in The Netherlands!

David Kipling Apparently it's supposed to have oral tentacles (not seen in A pseudo). Which I guess means flipping it on its back?

Niels Schrieken Correct David Kipling . But if you don't want to flip it over Geitodoris planata can be distinguished from Archidoris pseudoargus by the light coloured stellate patterns on the mantle (acid glands).

Niels Schrieken The third difference is that at the underside of Geitodoris planata there are brown spots on the mantle.

David Kipling (so we have to flip it again!). Can we see the acid glands in this picture Niels?

Niels Schrieken Yes at least four glands are very obvious. Between the branchial plume and the rhinophores.

Niels Schrieken :-). I am not sure if we should say to the divers to flip over all the animals they see.

David Kipling Me too ;)

Jim Anderson In the examples I have seen the top of the rhinophore tapers to more of a point in G. planata -it's a wee bit subtle but seems to be consistent. The star shaped acis glands are usually more obvoius. We saw many of this species at Loch Creran last weekend.

David Kipling I'm going to be obsessively looking at ever Archidoris pseudoargus I see now ...

David Kipling SSF has a useful pic showing those stellate spots, and some description of G. planata versus A. pseudoargus : http://www.seaslugforum.net/find/geitplan

Brendan Oonk Try to flip some of the pics over ;)

Jim Anderson René, Lovely image - they are difficult to 'catch' with the gill and rhinophores on show.

René Weterings Thank you Jim, but there are so many of these nudi's right now, that it makes it a bit easier to "catch" them in a nice position for photography!

Bernard Picton I'm very interested to know what they are eating. They seem to eat several species of Mycale (a sponge). In Strangford Lough Mycale similaris became much commoner in the last 20 years, followed by the appearance of G. planata, for which there were no historical records.

Bernard Picton http://www.habitas.org.uk/marinelife/sponge_guide/sponges.asp?item=C5540

René Weterings They eat "Mycale micracanthoxea" according to Peter van Bragt.

Bernard Picton Thanks René, I was interested to know if you had seen them on other Mycale species. 30 years ago we only found them on the bright red Mycale rotalis. M. micracanthoxea was only named in 1977 and I wondered if it might be an invasive species of sponge. I'm interested in observations of possible interactions between invasive sponges and tunicates and nudibranch predators.

Niels Schrieken http://www.anemoon.org/anemoon/spuisluis/2007/spuisluis/2001/011118.htm/?searchterm=Mycale%20micracanthoxea is showing the different characteristics of G. planata.

Peter H van Bragt Dear all, Mycale micracanthoxea is the only Mycale sponge found in Dutch coastal waters. It was most abundant in 1999 when G. planata first appeared in our southwestern estuary. Within 4 years the G. planata population exploded. We could locally easily spot 400+ individiuals on a single dive in the Eastern Scheldt and Lake Grevelingen. Some of remarkable size: up to 12 cm. Twice as large as reported in older literature. At that time the huge G. planata population almost completly depleted the Mycale population. Result was that in 2005-2006 G. planata almost completely disappeared, presumably due to food shortages, allowing the Mycale population to subsequently recover again. This recovery was supported by two relatively severe winters for which G. planata seems to be quite sensitive: 2009-2011. Bear in mind that the Netherlands is part of the northern distribution border of G. Planata and we have in the Eastern Scheldt and Lake Grevelingen a very extreme watertemperature window.: winter close to +1 degrees C. and in summer >20 degrees C. Only this year G. planata is quickly developing a dense population in the Eastern Scheldt again. At this moment >100 per dive locally already. Needless to say, at this moment Mycale micracanthoxea is very abundantly present again! Most likely the absence of predators and pathogens at the introduction in 1999-2004 contributed also to the populaion explosion and extreme sizes. Cheers, Peter H. Peter H van Bragt

René Weterings Thank you Peter!

Vinicius Padula Dear all, I have interest in study this species (G. planata). Could some of you collect 2-3 specimens?

Brendan Oonk Surely that will be posible. What do you need them for/(What is your study)?

Paula Lightfoot Hi, I'm just re-reading these interesting comments about Geitodoris planata as I've just been told of three records made on the Yorkshire coast in 2010 and 2012. I see there is a record from Brander Point St Abbs in 2007 although this record doesn't seem to have turned up on the NBN Gateway yet. Jim Anderson do you know if the St Abbs record has been sent to the Conchological Society? I'd be interested to know if anyone else has reports of this species on the east coast and what it might be feeding on here. The three Yorkshire records were found intertidally. Thanks Brendan Oonk for the brilliant photos showing the dark spots and oral tentacles, I am going to look very closely at any 'sea lemons' I find in future and these will be useful!

Jim Anderson Paula Lightfoot - I thought that I had notified them but may be mistaken. I have east coast (St. Abbs/Eyemouth) records of it from Oct 2004, August 2006, Jun 2007, July 2007 and June 2010.

Message posted on NE Atlantic Nudibranchs on 10 Oct 2012
Jim Anderson Geitodoris planata Loch Creran, Scotland September 2012 30 mm animal atop a queen scallpop, Aequipecten opercularis, that appears to have been feeding on the encrusting sponge

Ian Smith Super picture Jim Anderson . Any idea what species of sponge David Kipling?

David Kipling Looks like an undercooked drop scone ;)

Bernard Picton This sponge is probably the same one which was common in Strangford Lough when we still had an Aequipecten opercularis population. If so it is a Mycale, similar to Mycale macilenta but in my opinion probably undescribed. Nice that you still have big Aequipecten in Loch Creran, Jim.

Jim Anderson There are thousands - they kept swimming across the view while trying to take photographs.

Message posted on NE Atlantic Nudibranchs on 11 Oct 2012
René Weterings "Geitodoris planata" in close up This nudi is making it's return in the Eastern Scheldt, since it's disappearing in early 2010. I have found over 10 examples in 1 dive on divesite "Zoetersbout" on the 26th of september 2012.

Message posted on NE Atlantic Nudibranchs on 28 Sep 2012
René Weterings "Geitodoris planata" @ Divesite "Zoetersbout", Easterscheld The Netherlands For me it was already more than 1,5 years, that I found this nudibranche in the Dutch waters....!! It sat at 6,5m at intermediate tide, west of the stairs, including eggs!!

Arne Kuilman Nice find! Haven't seen it in 2 years either.

Rob Maller Nice to have them back indeed!

Tony Gilbert Not sure which is the synonym now, but I know it as Discodoris planata, characterised by the acid glands. There is a similar southern speices. Just last weekend, I spotted and photographed one in Loch Long am sure Jim Anderson would be interested, as it was near Tighness slip.

Jim Anderson It's Geitodoris planata.

Brendan Oonk WoRMS says Geitodoris planata is the accepted name'

Tony Gilbert Ok, thanks. When I spotted mine I thought of xx.planata, and couldn't make up my mind --- underwater. I find it easier by naming things underwater as I go along.

João Pedro Silva Further south there's also Discodoris stellifera, very hard to tell both appart without examining the radula.

Peter H van Bragt Hi René, it seems that they may be emerging again this year. Several records already at Zeelandbrug with spawn and Burghsluis too.

René Weterings Yes, I think so too Peter, other divers have spot them too at different divesites. Also on the south side of the Eastern Scheldt.

Message posted on NE Atlantic Nudibranchs on 31 May 2012
João Pedro Silva About 1cm long in Arrábida, Portugal approximately 3m deep. Me and Gonçalo Calado at first thought it might be a juvenile Geitodoris planata (plenty around) but as we saw the photos we stood puzzled by the lack of the characteristic white star shaped spots. Next wednesday we're going back to try to find it and hopefully collect a specimen.

Bernard Picton The mantle seems to have an almost reticulate raised pattern - like the surface of a sponge. We need Angel Valdes here for an insight into that. It's not like anything I've seen before, but you have a lot of things there in Portugal which I thought were just Mediterranean species.

João Pedro Silva Lucas Cervera has seen this and doesn't know what species this may be.

Bernard Picton Or genus... need the radula and anatomy..

Bernard Picton Is Lucas on FB? I just asked Marta Pola to join us.

João Pedro Silva The "problem" is that we're in a sort of crossroads between the Mediterranean and the Atlantic. We're going to try to find it again for collection. I think Lucas has no FB profile.

João Pedro Silva Added to the "unidentified" album.

Bernard Picton We could set up an Unidentified group and share those posts there? Might work better than an album?

João Pedro Silva not sure if that wouldn't complicate things as the photos are first being discussed here and then added to the Unidentified album. An "Unidentified" group would have its own discussions and the member list could even be different than this group's.

Bernard Picton True. When you share the item doesn't take its discussion with it...

Christian Skauge It's a damn shame that it is not possible to move images AND discussions to other albums, a really dumb thing about FB. But I also see their point - stuff could be put into a completely differrent context at a later time, possibly a VERY bad thing if misused intentionally...

João Pedro Silva Then again, it is possible to post an image and move it (comments included) from album to album in "Pages". My wife has her business page on FB and she can do it.

João Pedro Silva When she starts making models of nudibranchs I'll post the link here :)

Christian Skauge Yes, in pages it works - but there everything is your own. In a group I would potentially be able to move other people's images+comments into a new album called "I love Berlusconi" or something similar that would totally ruin your reputation...

João Pedro Silva But a page can accept publications from other people and have more than one admin. The only thing different is that you can invite people to "like" your page... but you can't prevent the people you don't like from doing the same.

Christian Skauge Ture, maybe a page would be better than a group in some ways. But as you say, you can't control who likes your page... haha weird and backwards, bet FB never thought that would be a problem :-)

Message posted on NE Atlantic Nudibranchs on 05 Feb 2012
João Pedro Silva Geitodoris planata Local: Arrábida, Portugal Spot: Alpertuche Profundidade: 4m Data: 26-12-2011

María Eugenia Suárez Tienes alguna foto de este nudi por su parte inferior? Hace tiempo vi una parecida dada la vuelta por un aletazo y me gustaría saber si es la misma. Gracias.

João Pedro Silva Tenho algumas fotos de pormenor mas não as tenho online. São laranja/amarelado com pequenos pontos castanho-escuro. Mas... Discodoris stellifera também tem os mesmos pontos: http://www.flickr.com/photos/jpsilva1971/6824861188/

João Pedro Silva As duas espécies (D. stellifera e G. planata) são tão semelhantes que apenas a observação microscópica da rádula as permite distinguir (como entre Trapania hispalensis e Trapania tartanella). Mas os recentes estudos genéticos vieram confirmar que determinados aspectos morfológicos (como a rádula ou as mandíbulas) podem variar dentro de uma mesma espécie. E pode ser que, quando se fizer a revisão da família Discodorididae com recurso ao ADN, se descubra que afinal se trata da mesma espécie.

Message posted on Nudibranquios on 01 Sep 2013
Antoni López-Arenas Cama Another opisthodoubt from the same dive: http://www.flickr.com/photos/alopezarenas/9296152954/in/photostream/lightbox/ http://www.flickr.com/photos/alopezarenas/9296152292/in/photostream/lightbox/

João Pedro Silva Good question. Not sure. Does remind a bit some more uniformly coloured Geitodoris planata. http://www.flickr.com/photos/jpsilva1971/6578323353/

Brendan Oonk G. planata does have light star shaped acid glands, which I don't see in this picture.

Ian Smith The rhinophores and gills look right for planata. Light stars vary in their development; on some of your Flickr images I can see the large white acid producing tubercles and the white "star-material" seeping round the orange body tubercles. There is a selection of specimens, including an orangey one, and close ups of rhinophores & gills at http://www.conchsoc.org/spAccount/geitodoris-planata (make sure to click along the thumbnail strip as many images hidden on right). I'd say your det. is right. Did you check under the mantle for blotches (but sometimes absent)?

Ian Smith I'd better add a note of caution. I misread the location as Calais on le Manche; you have more possibilities in Cataluña.

Antoni López-Arenas Cama Any suggestion? :-P

Ian Smith Sorry, I'm not experienced in Med. spp. I've asked Jakov Prkic in Croatia if he thinks if it's ok for planata or if he has a suggestion. I'll let you know if he opines anything. I'm sure you'll know if you've looked on Bill Rudman's old Sea Slug Forum that the group is notorious for Opisthodoubta; I like the term you coined :-) BTW, you have a great selection of lovely images on Flickr. Before posting this I've just checked in Schmekel & Portmann "Opisth. des Mittelmeeres". Their illustration of Platydoris argo Tafel 3:3&4 is very close your image. If you have, or can borrow, a copy, it would be worth working through the text to see if you can match the features (the sheath round the rhinophore socket seems a bit high in their illustration). Schmekel says of P.argo, "gills orange with brownish red and opaque white dots at the tip." I can see opaque white tips on your image http://www.flickr.com/photos/alopezarenas/9293373621/in/photostream/lightbox/

Antoni López-Arenas Cama I think Platydoris argo has a typical granular texture and my specimen has a bigger glands. I would like to have this book, but it's very expensive :-P Some day... Thank you very much.

João Pedro Silva Brendan Oonk, the glands may not always be so conspicuous. One of the individuals on the photo I posted above does have them but are only noticeable in detail: http://www.flickr.com/photos/jpsilva1971/6578301813/ Regarding the P. argo possibility, the texture is very different from Antoni's individual: http://www.flickr.com/photos/jpsilva1971/7645095810/

João Pedro Silva Gonçalo Calado, did we get a verdict from this one from Alpertuche last year? Reminds be a bit of Antoni's photo: http://www.flickr.com/photos/jpsilva1971/6751588775/

João Pedro Silva There's an "Unidentified" album in this group. I've uploaded last year a more detailed crop: https://www.facebook.com/photo.php?fbid=3253540898442&set=oa.167103413400947&type=3&theater

Gonçalo Calado It could also be a Thordisa, I think

João Pedro Silva The papillae in Thordisa filix and T. azmani seem less dense and thinner than the ones in this individual (and also on the one I shot later but not collected: http://www.flickr.com/photos/jpsilva1971/6896123624/)

Ian Smith I agree not P argo. Joao's images show the texture convincingly and the white tips on the gills to be far more extensive than I'd realised. I'd better leave southern stuff to you southerners. Toni you are right about Schmekel; greatly overpriced, but worth searching the web occasionally. I hit lucky and got a perfect like-new copy for £70 instead of usual £300. But do we really need Schmekel now Joao's Algarve book is available?

Ian Smith Jakov Prkic replied to my enquiry: Regarding Toni's images, the specimen certainly is not Platydoris argo. I think it belongs to planata-stellifera complex, where we can add also Geitodoris portmanni, a very doubtful species, closely related to stellifera. Toni's specimen has some features which correspond with original description of G. portmanni (redish/orange colour, large and conical tubercles, shape and number of gills, ...). But it has also a very unusual colour of the gills (there are two different colours!!), so this feature complicates its ID. In my opinion Toni's slug is more similar to stellifera/portmanni than to planata.

Lucas CerCur It is not T. filix nor T. azmanii. I agree that could be a "Geitodoris", but..... Again, we need to check internal anatomy to have some light, although it is probable that a definitive ID could be not obtained only from the anatomy.

Egidio Trainito The problem is that this is a very small specimen

Message posted on NE Atlantic Nudibranchs on 15 Jul 2013
René Weterings Geitodoris planata.....one of the "thousands" that can be found in the Eastern Scheldt at the moment in The Netherlands!

David Kipling Apparently it's supposed to have oral tentacles (not seen in A pseudo). Which I guess means flipping it on its back?

Niels Schrieken Correct David Kipling . But if you don't want to flip it over Geitodoris planata can be distinguished from Archidoris pseudoargus by the light coloured stellate patterns on the mantle (acid glands).

Niels Schrieken The third difference is that at the underside of Geitodoris planata there are brown spots on the mantle.

David Kipling (so we have to flip it again!). Can we see the acid glands in this picture Niels?

Niels Schrieken Yes at least four glands are very obvious. Between the branchial plume and the rhinophores.

Niels Schrieken :-). I am not sure if we should say to the divers to flip over all the animals they see.

David Kipling Me too ;)

Jim Anderson In the examples I have seen the top of the rhinophore tapers to more of a point in G. planata -it's a wee bit subtle but seems to be consistent. The star shaped acis glands are usually more obvoius. We saw many of this species at Loch Creran last weekend.

David Kipling I'm going to be obsessively looking at ever Archidoris pseudoargus I see now ...

David Kipling SSF has a useful pic showing those stellate spots, and some description of G. planata versus A. pseudoargus : http://www.seaslugforum.net/find/geitplan

Brendan Oonk Try to flip some of the pics over ;)

Jim Anderson René, Lovely image - they are difficult to 'catch' with the gill and rhinophores on show.

René Weterings Thank you Jim, but there are so many of these nudi's right now, that it makes it a bit easier to "catch" them in a nice position for photography!

Bernard Picton I'm very interested to know what they are eating. They seem to eat several species of Mycale (a sponge). In Strangford Lough Mycale similaris became much commoner in the last 20 years, followed by the appearance of G. planata, for which there were no historical records.

Bernard Picton http://www.habitas.org.uk/marinelife/sponge_guide/sponges.asp?item=C5540

René Weterings They eat "Mycale micracanthoxea" according to Peter van Bragt.

Bernard Picton Thanks René, I was interested to know if you had seen them on other Mycale species. 30 years ago we only found them on the bright red Mycale rotalis. M. micracanthoxea was only named in 1977 and I wondered if it might be an invasive species of sponge. I'm interested in observations of possible interactions between invasive sponges and tunicates and nudibranch predators.

Niels Schrieken http://www.anemoon.org/anemoon/spuisluis/2007/spuisluis/2001/011118.htm/?searchterm=Mycale%20micracanthoxea is showing the different characteristics of G. planata.

Peter H van Bragt Dear all, Mycale micracanthoxea is the only Mycale sponge found in Dutch coastal waters. It was most abundant in 1999 when G. planata first appeared in our southwestern estuary. Within 4 years the G. planata population exploded. We could locally easily spot 400+ individiuals on a single dive in the Eastern Scheldt and Lake Grevelingen. Some of remarkable size: up to 12 cm. Twice as large as reported in older literature. At that time the huge G. planata population almost completly depleted the Mycale population. Result was that in 2005-2006 G. planata almost completely disappeared, presumably due to food shortages, allowing the Mycale population to subsequently recover again. This recovery was supported by two relatively severe winters for which G. planata seems to be quite sensitive: 2009-2011. Bear in mind that the Netherlands is part of the northern distribution border of G. Planata and we have in the Eastern Scheldt and Lake Grevelingen a very extreme watertemperature window.: winter close to +1 degrees C. and in summer >20 degrees C. Only this year G. planata is quickly developing a dense population in the Eastern Scheldt again. At this moment >100 per dive locally already. Needless to say, at this moment Mycale micracanthoxea is very abundantly present again! Most likely the absence of predators and pathogens at the introduction in 1999-2004 contributed also to the populaion explosion and extreme sizes. Cheers, Peter H. Peter H van Bragt

René Weterings Thank you Peter!

Vinicius Padula Dear all, I have interest in study this species (G. planata). Could some of you collect 2-3 specimens?

Brendan Oonk Surely that will be posible. What do you need them for/(What is your study)?

Paula Lightfoot Hi, I'm just re-reading these interesting comments about Geitodoris planata as I've just been told of three records made on the Yorkshire coast in 2010 and 2012. I see there is a record from Brander Point St Abbs in 2007 although this record doesn't seem to have turned up on the NBN Gateway yet. Jim Anderson do you know if the St Abbs record has been sent to the Conchological Society? I'd be interested to know if anyone else has reports of this species on the east coast and what it might be feeding on here. The three Yorkshire records were found intertidally. Thanks Brendan Oonk for the brilliant photos showing the dark spots and oral tentacles, I am going to look very closely at any 'sea lemons' I find in future and these will be useful!

Jim Anderson Paula Lightfoot - I thought that I had notified them but may be mistaken. I have east coast (St. Abbs/Eyemouth) records of it from Oct 2004, August 2006, Jun 2007, July 2007 and June 2010.

Message posted on NE Atlantic Nudibranchs on 10 Oct 2012
René Weterings "Geitodoris planata" @ Divesite "Zoetersbout", Easterscheld The Netherlands For me it was already more than 1,5 years, that I found this nudibranche in the Dutch waters....!! It sat at 6,5m at intermediate tide, west of the stairs, including eggs!!

Arne Kuilman Nice find! Haven't seen it in 2 years either.

Rob Maller Nice to have them back indeed!

Tony Gilbert Not sure which is the synonym now, but I know it as Discodoris planata, characterised by the acid glands. There is a similar southern speices. Just last weekend, I spotted and photographed one in Loch Long am sure Jim Anderson would be interested, as it was near Tighness slip.

Jim Anderson It's Geitodoris planata.

Brendan Oonk WoRMS says Geitodoris planata is the accepted name'

Tony Gilbert Ok, thanks. When I spotted mine I thought of xx.planata, and couldn't make up my mind --- underwater. I find it easier by naming things underwater as I go along.

João Pedro Silva Further south there's also Discodoris stellifera, very hard to tell both appart without examining the radula.

Peter H van Bragt Hi René, it seems that they may be emerging again this year. Several records already at Zeelandbrug with spawn and Burghsluis too.

René Weterings Yes, I think so too Peter, other divers have spot them too at different divesites. Also on the south side of the Eastern Scheldt.

Message posted on NE Atlantic Nudibranchs on 31 May 2012
João Pedro Silva From this morning's dive. Appears to be the same me and Gonçalo Calado found by the end of January (http://www.flickr.com/photos/jpsilva1971/6751608437/). I think it's relatively safe to say this sponge is its prey.

Bernard Picton Did you get a bit of the sponge João? If it was here I'd say Mycale rotalis, based on colour and surface appearance. Geitodoris planata seems to eat Mycale similaris in Strangford Lough, but Mycale rotalis in some other places. I guess it could be a red variant, you get that in Doris pseudoargus feeding on red Suberites ficus (assuming that it really is D. pseudoargus, A & H named it D. flammea).

João Pedro Silva I didn't collect it, Bernard. Although I can find the exact spot (to the cm) where it is. This is in a small wreck just outside the Sesimbra harbour.

Message posted on NE Atlantic Nudibranchs on 03 Apr 2012
João Pedro Silva Still trying to figure out the identity of this guy. It appears to be the same species as the one shot last January (http://www.flickr.com/photos/jpsilva1971/6751569889/). Great camouflage... also still trying to figure out how I saw it.

Henrique Nascimento Catarina there is anyone out there ???? please Nudi Lovers, can help to identify this one... thanks :)))

Linda Goldrich Have you tried posting it on the critter id forum at wet pixel?

João Pedro Silva Thanks, Linda! I wasn't hoping to get the answer here, just saying I'm still trying to figure its identity. This has already been shown to many top specialists on opistobranchs of the NE Atlantic. It may be a colour form of a known species (perhaps Geitodoris planata) or a food induced colouration but I'll have either to collect the nudibranch or the sponge it's feeding on... or both.

Message posted on NUDIBRANCH LOVERS on 05 Apr 2012
Orietta Rivolta Discodoris stellifera (Vayssière,1904) Numana,Italy

João Pedro Silva Have you also found Geitodoris planata? Those are really hard to distinguish.

Orietta Rivolta No, never seen Geitodoris planing. The ID of my nudibranchs in Italy were made by the biologist Federico Betti.If it were Geitodoris planata I've one more species!

João Pedro Silva They're very difficult to distinguish.

Message posted on EPAM Nudibranchs on 05 Jun 2012
Taxonomy
Animalia (Kingdom)
  Mollusca (Phylum)
    Gastropoda (Class)
      Heterobranchia (Subclass)
        Opisthobranchia (Infraclass)
          Nudibranchia (Order)
            Euctenidiacea (Suborder)
              Doridacea (Infraorder)
                Doridoidea (Superfamily)
                  Discodorididae (Family)
                    Geitodoris (Genus)
                      Geitodoris planata (Species)
Associated Species