Fryeria bayi
Bouchet, 1983

Suborder: DORIDINA
Family: Phyllidiidae


Endemic to the Mediterranean Sea.


38 m depth, Punta Bianco, Corse, Mediterranean Sea, Aug. 1981, dorsolateral view of 8 mm specimen, Photo: C. Huygens (Brunckhorst, 1993: Plate 5D).

Notes compiled from Brunckhorst, 1993:
The pale cream dorsum with its fine, pale brown, mottled pattern sets F. bayi apart from all other Fryeria species. The dorsal intestinal sac is also unique to this species.

Fryeria rueppelii, Fryeria guamensis, Fryeria menindie and Fryeria marindica all have a black background, gold-yellow capped tubercles and gold rhinophores (pale cream in F. bayi). Fryeria larryi is closer to F. bayi, but it has yellow coloration (no brown pigmentation) and is not mottled. In contrast, F. larryi possesses a few red, transverse lines which occur laterally.

Note: See message discussing whether this species should be in the genus Phyllidiopsis.

Brunckhorst, D.J. (1993) The systematics and phylogeny of Phyllidiid Nudibranchs (Doridoidea). Records of the Australian Museum, Supplement 16: 1-107.
• Bouchet, P (1983) Decouverte du genre Indo-Pacifique Fryeria (Mollusca, Gastropoda, Nudibranchiata) en Mediterranee. Annales de l'Institut Oceanographique, 59(1): 65-68.

Authorship details
Rudman, W.B., 1999 (July 15) Fryeria bayi Bouchet, 1983. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Re: Phyllidiopsis bayi or Fryeria bayi

March 28, 2002
From: Angel Valdes

Dear Bill,
Thank you very much for your comments on the paper that Terry and I wrote on the phylogeny of the radula-less dorids.

There are three points that I would like to discuss here:

1) The question of the generic placement of Fryeria bayi. - I have examined all specimens of this species collected so far, including the type material from the Paris museum and additional specimens from the Madrid museum. All the specimens examined have a long buccal bulb with microscopic and simple oral glands, and the oral tentacles are fused together. Also, all of them have a ventral anus. As you said Brunckhorst characterized the genus Fryeria on the basis of several anatomical features in addition to the position of the anus, including oral tentacles separated and short buccal bulb with large oral glands. Fryeria bayi is anatomically identical to other species of Phyllidiopsis. Another species of Phyllidiopsis, P. blanca, may have a ventral anus, so there is no question to me that F. bayi should be transferred to the genus Phyllidiopsis.

2) The question of the monophyly of the radula-less dorids.- You are right, our paper is just a preliminary step in trying to understand the relationships of this group of opisthobranchs. We found, based on the observation of anatomical characters and a phylogenetic analysis that the radula-less dorids are a monophyletic group. However, I agree that more information should be collected before a definitive conclusion. Gilianne Brodie is working on histological characters for this group and she is finding similar results. I do not think it is appropriate for me to talk about her work here, but it would be nice if Gilianne could send a note to the Forum with her ideas about this problem. I have also been working on molecular characters (based on the 16S gene) and the conclusion is clear again: the radula-less dorids are monophyletic. I am now in the process of publishing my molecular results. I believe that very soon we would be able to show enough evidence to convince most opisthobranch specialists that the radula-less dorids are monophyletic.

3) The question of the validity of Fryeria.- The variability of the position of the anus in Phyllidiopsis bayi is not the only reason to synonymize Fryeria with Phyllidia. The main reason is that Fryeria, even though is a monophyletic group (once F. bayi is excluded), characterized by the presence of a ventral anus, is a clade nested within the larger Phyllidia clade. Right now we are using a rank-based nomenclatural system so we are not allowed to name monophyletic groups unless we can fit them in a particular category, such as genus, family, etc. At the same time, because of all us believe in evolution, we do not name paraphyletic groups anymore. If Fryeria is maintained as a valid genus, this would render Phyllidia paraphyletic, and this is undesirable. On grounds of nomenclatural consistency Fryeria is regarded as a synonym of Phyllidia. If one day we would be able to agree to a rank-free system of classification we could reinstall the name Fryeria with no rank.

Thanks very much again for your thoughts,

Valdes, A., 2002 (Mar 28) Re: Phyllidiopsis bayi or Fryeria bayi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Angel,
Thanks for your comments. I am glad we agree on most things. What I find most frustrating is how little anatomical information has actually been published. By information I mean diagrams and illustrations of actual dissections. Even Brunckhorst's extensive monograph (1993) has few anatomical diagrams and usually only the type species of each genus is described. This means that the only way to review such work is to do it again, which is just not practical. For example, there are a number of comparative tables in Brunckhorst which suggest that as well as the position of the anus, there are considerable anatomical differences in the foregut and reproductive systems of Phyllidia and Fryeria. I would like to be able to make my own judgement on that, but the published evidence is not there for me to do so. Similarly with species of Phyllidiopsis, it would be useful if sufficient evidence could be presented to the reader for them to make an 'armchair' judgement on the hypothesis being presented to them. I have searched the literature for some anatomical illustrations of different species which would allow me to get a feel for the similarities and differences but can't find them. One growing problem is that many authors are replacing illustrative information with data matrices and tables of character states. This makes it almost impossible for readers to make a judgement on the hypothesis being presented, unless they are willing to 'trust' the authors to have interpreted the anatomy correctly [NB: I don't include the well-illustrated Valdes & Gosliner, 1999 in this comment]. I realise that illustrations can be 'doctored' but at least if there are detailed illustrations available the reader can see what the author has in mind, and make a judgement on whether they agree with how the author has interpreted the anatomy. Without naming names, I once had a puzzling correspondence with a colleague over the anatomy of an animal. It only became clear when they sent me a diagram of the anatomy, that they had confused part of the reproductive system with the alimentary canal. Easy enough to do, but a fatal and untraceable error, if all a reader has to work on is a character matrix based on an anatomical error.

Sorry I am making this so long. Let's discuss you last point - the 'paraphyly' of Fryeria. I think its a bit early to say we understand the evolution of this group. In your cladistic analysis you only include one species of each genus and one branch of your cladogram ends up with an unresolved trichotomy consisting of Phyllidia varicosa, Fryeria marindica [in the middle] and Phyllidiella pustulosa. You may have later cladograms with more species analysed, but the one in your 1999 paper doesn't look as though the evidence for Fryeria nesting in the middle of a large Phyllidia clade is very strong. Have you published a later analysis with more species?
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Mar 28). Comment on Re: Phyllidiopsis bayi or Fryeria bayi by Angel Valdes. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Monophyly of the porostomes

March 28, 2002
From: Terry Gosliner

Dear Bill,
I want to thank you for bringing up the discussion of the the recent paper that Angel and I published on the radula-less dorids. I think the forum is a great place to have some of these ideas aired and certainly appreciate your perspective. I know Angel has also sent you a response, but I also wanted to add some of my thoughts.

I think readers should know that this kind of discussion is what we systematic biologists live for and while it may be considered by some to sound adversarial, it is how our science progresses. Secondly, systematic biology or how we classify organisms has undergone some major changes over the past several decades that represent a major change in how we do our work. Not all of these new ideas are universally embraced and even those who use these techniques use them slightly differently and can reach different conclusions. One of the fundamental ideas of this new approach (called cladistics or phylogenetic systematics) is to recognize only monophyletic groups. These are groups that include a common ancestor and all of its descendants. These groups must share advanced characters as opposed to primitive ones. Many traditional taxonomic groups such as the Invertebrata, Prosobranchia and Cephalaspidea do not have advanced characteristics shared by all of their members. Therefore, cladists (people who embrace this methodology) do recognize these traditional taxa as valid groups of organisms.

That is the philosophy. How does that translate into practice. Well, our contention with regard to the radula-less dorids (porostomes: traditionally the Dendrodorididae and Phyllidiidae) is that the radula was lost only once in this group and represents a shared, advanced characteristic that all of these species share. Bill, suggests quite accurately, that it is important to compare different lines of evidence to reach these conclusions. Angel and I put together anatomical characteristics from all organ systems and compared them. These ultimately led us to the conclusions we reported. Since then, Angel has also produced a new set of data based on mitochondrial genes form many representatives of nudibranchs. These data were evaluated independently and also support the idea that the radula-less dorids are more closely related to each other than to any other group of nudibranchs. Bill, suggested that it would be good to have histological (cellular makeup of organs) characters to support the idea that the organs that we considered to be of the same evolutionary origin (homologous). Interestingly, Gilianne Brodie presented a paper and published an abstract at the World Congress of Malacology in Vienna last August that also supports the idea that radula-less dorids are a monophyletic group. Thus, we now have three independent lines of evidence to suggest that the phyllidids are more closely related to the dendrodorids than to any other groups of nudibranchs. Does this mean that the case is closed? Certainly not! Science must continually test hypotheses with new evidence.

Bill also suggested that we had based our synonomy of Phyllidia and Fryeria on the examination of Atlantic species. This was not the case. What we found is that species Fryeria shared an advanced characteristic, the possession of a ventral anus. But when you separate Fryeria from Phyllidia, the remaining species of Phyllidia no longer share any advanced characteristic. Thus they are no longer in a monophyletic group. Separating Fryeria as a genus means that all the Phyllidia species are left hanging in space. This is the same basis by which we could no longer separate the aeolids in Coryphella from Flabellina.
While systematic biologists can often reach different conclusions and those differences appear frustrating to people who just need to have a stable name for a species that interests them, it is how science works. We don't make changes in names just to be difficult or egotistical. What is important in modern systematics is that we explain what assumptions we made and how we got to that point. Laying all of our cards out on the table then permits others to start where we left off rather than starting from scratch each time. Systematics is a great science because evolution is like a criminal leaving us clues through the fossil record, through the way in which different evolutionary adaptations are expressed in body shape and arrangement of organs or the molecular sequences of the DNA molecule. Like any good mystery, some of the clues will lead us in the wrong direction, but hopefully good detectives will be able to work together to solve the mystery of how evolution unfolded.
Terry Gosliner

Gosliner, T., 2002 (Mar 28) Monophyly of the porostomes. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Terry,
I think it would be wrong to give our readers the impression that all taxonomists are as polite and civilised as we are in our taxonomic debates. In fact, like all human endeavours, there are taxonomists who are outrageous, egotistical, self-opinionated, bigoted etc etc, and most of us have stories about colleagues and events which make humorous anecdotes in conference 'happy-hours'.

To return to our polite discussion. Basically I will be happy with any conclusion that is reached on the monophyly of the Porostomata, the position of Fryeria bayi and the relationship of Phyllidia and Fryeria. Interestingly, the concept of the Porostomata as a monophyletic group is more than 100 years old, but seemed to go out of fashion in the 1970s ironically because people were interested in evolutionary relationships and felt that the similar suctorial foregut in the Dendrodorids and Phyllidiids were just as likely to have evolved independently as to have had a common origin. It will certainly be interesting to see the publications on Gilianne's histological work and Angel's mitochondrial DNA.

My mention of the Atlantic species was really about the Phyllidiopsis - Fryeria bayi question. I have a philosophical difficulty with the same character apparently popping up independently a number of times in closely related groups. It seems quite logical to remove F. bayi from Fryeria but to place it in Phyllidiopsis and to merge Fryeria with Phyllidia means that we believe that there is some gene in the family which allows the anus to switch from dorsal to ventral, even within a single species. I think we should be asking geneticists whether this is a likely scenario.

I don't quite understand your point that removing the Fryeria clade from Phyllidia would render Phyllidia paraphyletic. This doesn't necessarily follow from your paper where you say "it is possible that members of the genus Phyllidia with a ventral anus could form a monophyletic subclade." Are you suggesting that perhaps we should consider Fryeria to be a subgenus of Phyllidia?
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Mar 28). Comment on Monophyly of the porostomes by Terry Gosliner. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Phyllidiopsis bayi or Fryeria bayi

March 13, 2002
From: Alma Sánchez

Dear Dr. Rudman
According to Valdés & Gosliner (1999), Fryeria bayi Bouchet, 1983 is transferred to the genus Phyllidiopsis on the basis to the presence of oral tentacles fused together and a buccal bulb very elongate and convoluted. For more information see:
• Valdés, A. & Gosliner, T. M. (1999). Phylogeny systematic of the radula-less dorids (Mollusca: Nudibranchia) with the description of a new genus and a new family. Zoologica Scripta, 28: 315 - 360

Best wishes,

Sánchez, A., 2002 (Mar 13) Phyllidiopsis bayi or Fryeria bayi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Alma,
Thanks for mentioning the Valdés & Gosliner (1999) paper. I have read it two or three times wondering how I should respond on the Forum. Traditionally in taxonomy, when major changes, or major ideas are proposed, it takes some years before a consensus has emerged on the 'rightness' or 'wrongness' of the proposal. With so few workers in the field it takes time before others are in the position to re-examine the evidence, do their own research and publish their thoughts. With the world wide web, and rapid ways to publish our thoughts, like the Forum, a new way of dealing with new ideas will have to emerge. If we act immediately, every time a new taxonomic decision is published, then I suspect we will descend into chaos very quickly. My feeling on this paper was to wait and see what others thought of the paper.

But since you have raised the topic we might as well open it up for discussion. it is after all the Sea Slug Forum. I have a few problems with it. Firstly I think that before we can clarify the relationship between the dendrodorids and the phyllidiids we need to have a clearer understanding of the homologies between the various parts of the foregut. Perhaps further histological studies will help or perhaps it may be possible to undertake embryological studies. However at the moment it seems to me we don't know. The most sophisticated cladistic analysis is only as good as the data that is put into it.

The main concern of the paper is to consider the phylogenetic relationships of all the 'radula-less' dorids. There is little discussion or much evidence presented concerning the inter-relationships of the phyllidiids. In the paper the authors decide that the genus Fryeria is superfluous and of the two species of Fryeria they deal with, they place one, F. marindica in the genus Phyllidia, and the other, F. bayi in Phyllidiopsis. They assert that the only character separating species of Fryeria from other phyllidiids is the position of the anus - opening ventrally in Fryeria and dorsally in all other genera. They may be right, but I think they raise many questions which I think deserve a much fuller study.

It is no surprise that the position of the anus has been used as a key character but Brunckhorst (1993) considers there are other characters in the foregut, and reproductive system that do differentiate the genera. Now again, he may be wrong, but I would like to see a publication that presents the evidence in more detail. I think we need to know about more than just the type species of these genera and we need to know just how much intraspecific variability there is in some of these characters.

To my knowledge, one specimen of one species, Phyllidiopis blanca, has shown variability in the position of the anus. It was described from the Pacific coast of central America (Gosliner & Behrens (1988) and one specimen was discovered to have a ventral anus. This one specimen seems to be the reason the authors consider the ventral anus to be a feeble character.

To the position of the Mediterranean Fryeria bayi. To my knowledge very few specimens have been examined. Valdes & Gosliner (1999) on the basis of the elongate buccal bulb and fused oral tentacles, consider that it should be considered a species of Phyllidiopsis despite its ventral anus. They might be right. However so few specimens of this species seem to have been examined that perhaps the reported ventral anus is an unusual occurrence in the species. Perhaps both the Atlantic species are better placed in Phyllidopsis. It does not necessarily follow that all Indo-West species of Fryeria should be placed in Phyllidia.

It seems a bit premature, on the basis of the peculiarites with these two Atlantic species, which may not be congeneric with the Indo-West Pacific species of Fryeria, to assert that they present sufficient evidence to show that Fryeria and Phyllidia are synonymous. Ventral gills do occur at times as an anomaly, after all Chromodoridella mirabilis Eliot 1905 was based on an aberrant animal of Hypselodoris infucata and Scott Johnson's photo shows a specimen of Chromodoris geometrica with the same feature. But the point is that these are unusual developmental faults. We wouldn't think of using them to suggest a phylogenetic relationship, so perhaps we shouldn't give the peculiarities of the two Atlantic phyllidiids much phylogenetic weight until we know more about their occurrence.

In summary, I think Valdes & Gosliner's paper presents some interesting ideas but I think we need more information. I also think that sorting out the validity of Fryeria is a separate question from the monophyly of the 'Porostomata'.

I'm sorry for such a long answer to your very short suggestion. At present I don't feel able to agree or disagree with the Valdes-Gosliner proposal that the radula-less dorids are a monophyletic group. I think in the long run it will depend on a fuller understanding of the homology of the foregut organs. When such a preponderance of characters are related to the alimentary canal, it does not matter whether you use your brain and a pen, or a sophisticated cladistics program, or both, the evidence must have a tendency to veer towards a close relationship.

Any thoughts very welcome
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Mar 13). Comment on Phyllidiopsis bayi or Fryeria bayi by Alma Sánchez. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from