The external features are not well known for many species of Pleurobranchaea, many species being known only from the anatomy of preserved specimens. Until we can match specimens, for which we know the living colour and shape, with these descriptions of preserved specimens, this genus will continue to cause identification problems. The photos on this page are unidentifiable at present. See Species List for identified species of the genus.
• Marcus, E. & Gosliner, T.M. (1984) Review of the family Pleurobranchaeidae (Mollusca, Opisthobranchia). Annals of the South African Museum, 93(1): 1-52.Authorship details
Rudman, W.B., 2003 (January 10) Pleurobranchaea spp [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/pleurobranchaea
November 25, 2009
From: Nahuel Farias
Concerning message #22819:
first of all, thanks for your feedback and maintain such a useful and interesting site. Your explanation about the sudden appearance of this species is another interesting alternative
I was looking for little more on photos in this forum as well on other websites, and this animal seems to me very similar to Pleurobranchaea maculata (?). In relation to P. inconspicua I found a record from Argentina in Muniain et al (2006). That work has very good color photos of living animals and I found it freely available at
- Muniain, C., N. E. Ardila, et al. (2006). Pleurobranchaea inconspicua Bergh, 1897 (Opisthobranchia: Pleurobranchidae): Redescription and distribution from Argentina and Colombia. Bonner zoologische Beiträge 55: 291-300.
Any news I have on this animal in the future I´ll add here.
firstname.lastname@example.orgFarias, N., 2009 (Nov 25) Re: Pleurobranchaea from Argentina. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22864
I should have noted that reference. It does indeed have some nice photos. Your animal does look quite like P. maculata but without anatomical comparisons we can't be sure. I look forward to more news from you and if we are lucky, perhaps someone familar with the South American fauna may have some suggestions.
November 23, 2009
From: Nahuel E. Farias
I´m interested in to determine which species is this, I believe is an alien one. A few months ago I started to find many of these in an area that I dive regularly and I did never see it before. I´m sure it is a Pleurobranchaea but does not looks like P. inconspicua, which is the only recorded in this zone to the best of my knowledge.
Any idea is gratefully received
Locality: Mar del Plata, 5 meters, Argentina, Southwestern Atlantic, 12 September 2009, Rocky Boulders inside Port. Length: 93 mm. Photographer: Nahuel E. Farias.
Nahuel E. Farias
email@example.comFarias, N.E., 2009 (Nov 23) Pleurobranchaea from Argentina. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22819
Tha lack of a hooked spur on the posterior part of the foot would suggest is not P. inconspicua. Although an 'alien introduction' could be one explanation, another could be that you are witnessing a natural event where a species is sometimes present and then may disappear for some years, perhaps because of some local event or irregularity of currents etc. Unfortunately species of Pleurobranchaea are not that easy to identify even when the anatomy is known. For example, Marcus & Gosliner (1984), in the only review of the genus, consider P. hedgpethi Abbott, 1952 and P. gela Marcus & Marcus 1962 to be synonyms of P. inconspicua and state that anatomical differences that the Marcus's had previously reported in the reproductive systems of P. hedgpethi and P. gela were probably the result of contraction in the preserved animals.
Marcus's specimens of P. inconspicua from Brazil (which they named P. hamva Marcus & Marcus, 1957) is the closest record I can find of a Pleurobranchaea to yours. It is possible yours is one of the other species described from further north in the west Atlantic but is also possible it is a species which occurs on the southwest coast of Sth America, but I don't think any species have been described from there.
All I can suggest is for you to contact a local natural history museum and see if they will add some specimens to their collections for future research. It would also be valuable to have them include some copies of your excellent photos, as one of the problems with research on these species is the lack of information on the shape and colour of the living animals.
Also if you have photos of P. inconspicua they would be a valuable addition to the Forum.
- Marcus, E. and E. Marcus (1957). Sea-hares and side-gilled slugs from Brazil. Boletim do Instituto Oceanografico 6(1-2): 3-48.
- Marcus, E. and T. M. Gosliner (1984). Review of the family Pleurobranchaeidae (Mollusca, Opisthobranchia). Annals of the South African Museum 93(1): 1-52,Figs1-25.
January 22, 2003
From: Ferda Buyukbaykal
Could you identify this please? Is it Pleurobranchaea meckelii?
Image Data: Camlik, Fethiye, Mugla, Turkey. July 2000, 8-10mt / 6-7cm, Sea grass bed.
firstname.lastname@example.orgBuyukbaykal, F., 2003 (Jan 22) Pleurobranchaea sp. from Turkey. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/8937
This is obviously the same species as the one in your earlier message, but as I said there, until its anatomy is studied I thinkl it is impossible to be sure which species it is
January 11, 2003
From: Ferda Buyukbaykal
Could you identify this photo please?
Data: Fethiye, Mugla, Turkey. September 2000, Depth: 8mt, length: 8-10cm, night dive sea grass bed.
email@example.comBuyukbaykal, F., 2003 (Jan 11) Pleurobranchaea sp from Turkey. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/8887
This is a species of Pleurobranchaea but it is not possible to identify it without looking at its anatomy. Some authors consider that there is probably only one species in the Mediterranean, Pleurobranchaea meckelii, but in Marcus & Gosliner's (1984) review they recognise a number of species from western Europe and including 2 new species from the Mediterranean, including P. notmec from Turkey. Unfortunately they were described from a few preserved specimens so we have no knowledge of the appearance of living animals. All I can do is start a page for unidentified species of Pleurobranchaea.