I yesterday posted some further information comparing the anatomy of Philine auriformis from New Zealand and Californian "species 2". I think it shows that they are different species. I also posted some SEM photos of the radular teeth of those two species and of Californian "species 1" and Philine orientalis? from Hong Kong, for general information.

To those of you wanting an "easy" way to identify which Philine species you are studying, and what name to give it, I'm afraid there isn't one. Although this exercise in defining Philine identity (or should I say identities) in California is incomplete - we know what they aren't, but not what they are, it well illustrates the many gaps in our knowledge. .. Bill Rudman.

Dear Michelle,
I'm glad to have been able to help and I am enjoying looking at these animals for a change. The whole point behind the Forum is to get some interactivity going and to generate some interest in opisthobranch biology. When I came to the Australian Museum many years ago I brought a collection of specimens, mainly shells, of animals I had worked on in New Zealand. I didn't think there were any whole specimens of Philine auriformis but on checking this morning I find there are two! I don't know what condition they are in, after 30 years in preservative, but I'll let you know if I find anything interesting. .. Bill Rudman.

Glad to hear from you Terry. From what you say, it certainly looks like you have 3 introduced species of Philine. I think it is much more sensible if I direct enquiries about Californian Philine to you. When I innocently asked Michelle to send me a couple of specimens I didn't realise I would be opening Pandora's Box! Please use the Sea Slug Forum to keep us all informed of any discoveries. I have had a look specimens of a Philine from Hong Kong, which Morton & Chiu identified as Philine orientalis. It looks identical to Michelle's Species 1 from Bodega Bay. I'll post pictures of its shell and gizzard plates as soon as I get a chance to photograph it. If you have a photo of the shell and gizzard plates of the third species (Philine auriformis), which I could post on the site, or could send me a specimen to dissect and photograph it would be a useful comparison ... Bill Rudman

Dear Mike,
Thanks for the message. Have a look at Terry Gosliner's message today. Sorry but it looks like you have three species of Philine . Please keep us posted on developments...Bill

After receiving Terry Gosliner's message today I redissected the penis of the 3 specimens of Philine sp2 (Philine auriformis), which Michelle had sent me from Bodega Bay. In all cases the penis fitted his description. Clearly the seminal duct had broken in the one I drew making it look like a blind sac. While I found his suggestion of a penial transplant an amusing possibility, perhaps I need an eye transplant! What does still puzzle me is that the penial structure in Californian species 2 is about third to a quarter the size of a New Zealand Philine auriformis and the prostate forms a tight tangled mass rather than large loose folding. I am still unhappy about identifying this species with the New Zealand species until the anatomy of more Japanese possibilities are known. Unfortunately I don't have any specimens of NZ Philine auriformis available for comparison and am relying on notes I made many years ago.

So where does that leave the Californian Philine story? If you are doing ecological work there are definitely 2 species present. One may be Philine auriformis and the other is possibly a species from the NW Pacific, Philine orientalis . I will post pictures tomorrow of a species from Hong Kong which looks very similar to California Species 1, and make some corrections to the Philine pages. .. Bill Rudman

Michelle,
I just remembered we have some specimens of the Philine which Morton & Chiu studied in Hong Kong. So when I get a moment I'll dissect one and see how it matches your Species 1... Bill Rudman.

Some features of the anatomy of the Philine from California as described by Gosliner (1995) differed slightly from my studies of Philine auriformis. After receiving Michelle's photos of Californian Philine I asked her to send me some specimens as I was not entirely happy that the photos were of one species. I was also not sure whether it, or one of them, was really Philine auriformis. [NOTE added 5 August 1998: See correction re P. auriformis penis anatomy]

Rather than post all the emails that have passed between us over the last 2 weeks, I have now dissected some specimens that Michelle has sent me from Bodega Bay and there are definitely two species and neither of them is the New Zealand Philine auriformis. The description of the anatomy by Terry Gosliner (1995) refers either to a third species, or is a combination of parts of the anatomy of the two quite distinct species that Michelle has sent to me. I list the main anatomical features of the two species below. A comparison is made with two New Zealand species Philine auriformis and Philine angasi which are described in Rudman, 1970, 1972a, 1972b. Further images of each species can be found on separate pages for each species.

SPECIES 1. Gizzard plates relatively large. Two are mirror images of each other and the third, which is slightly smaller, is symmetrical in shape. The plates are flattened on the outside and have a pair of deep pin holes in the centre of the plate. The radular formula is 1.0.1, the teeth being large and hook-like with a denticulate inner edge. The penis has a long tangled tubular prostate gland filling much of the anterior body cavity beneath the foregut. The shell is smooth with no sign of sculpture. It has similarities to Philine angasi, in radula, gizzard plate and penis structure, but the shell is more constricted. One major difference is the relative size of the shell and gizzard plates, almost equal in length in Philine angasi, but in this species the larger plates are only about one half the length of the shell.

SPECIES 2. Gizzard plates are all of similar spindle shape with distinctive pits on the outside face, as illustrated by Gosliner. These are similar to those found in Philine auriformis. The radular formula is 1.1.0.1.1 with a large inner tooth on each side of the midline, flanked by an reduced outer tooth as illustrated by Gosliner. The penial sac is relatively small and the prostate is a small blind sac partially embedded in the longitudinal foot musculature. It is similar to the penis of Philine falklandica (see Rudman, 1972b). The shell has a spiral beaded sculpture as illustrated by Gosliner.

The animal described by Gosliner appears to have the shell and gizzard plates of Species 2 and the penis of Species 1. Since the penial complex in Species 2 is relatively small and partially hidden in the body musculature while in Species 1 the coils of the prostate gland are a prominent feature of the anterior body cavity it is easy to see how a mistake could be made if an investigator thought they were dealing with only one species.

Clearly neither species is Philine auriformis. Is it possible to identify them? Firstly there has been no published discussion on whether one or both these species is native to the West Coast of America rather than being introduced. To my knowledge three species have been described from that region, Philine bakeri Dall, 1919, Philine californica Willett, 1944 and Philine alba Mattox, 1958. We only have anatomical information for Philine alba which differs in having small gizzard plates, a radular formula of 2.1.0.1.2, and a quite different shaped shell. The other two species are only known from their shells, both of which are similar to Michelle's specimens. Macfarland (1966), publishes some photos of a Philine he identifies with Philine bakeri but gives no anatomical information.

Unfortunately there are many species of Philine described world-wide for which we have no anatomical information. In many cases, the fragile flattened shell is not enough to distinguish species. From the links on Terry Gosliner's webpage on the invasion in California it appears that many of the marine species are from Japan. Perhaps that is the most likely place to find the origin of these two species of Philine.

SPECIES 1 belongs to a group of species which includes Philine angasi, from New Zealand and southern Australia, and Philine aperta, from Europe, with two large mirror image gizzard plates and a third smaller plate. A third species in that group, Philine orientalis A. Adams, 1854, occurs in Japan and has been recently described from Hong Kong (Morton & Chiu, 1990). The shape of the teeth and the gizzard plates in that description are very similar to those of the Californian Species 1. A species, Philine kurodai Habe, 1946, which is now considered a synonym of Philine orientalis, has a smooth constricted shell just like the Californian animal. Although it would need a proper comparison with Japanese material, my guess is that Species 1 is probably Philine orientalis from Japan and China. If it is this species, Morton & Chiu (1990) has some interesting information on the feeding biology of it in Hong Kong.

SPECIES 2 has similarities to Philine auriformis but its penial anatomy is quite different. I know of no published description of a species with this combination of characters. If Species 1 is from Japan then it is probable that Species 2 is as well. Unfortunately I know of no anatomical studies of other Japanese species except for one description by Habe (1950) of a species he identified as Philine argentata Gould, 1860 which has a radula and gizzard similar to Species 1 but a dentate upper margin to the shell like in Philine powelli Rudman, 1970.

Sorry I can't be more definite. Your next problem is separating the two species in the field so your biological and ecological studies make some sense. I'm afraid as you have the living animals you are going to have to sort out a method. Species 1 seems to have more solid muscular parapodia and so appears more diamond shaped, while Species 2 has thinner parapodia making the body more cylindrical in shape. As a guess I would say the upper photo you sent is of Species 2 and the lower one is of Species 1. A quick way with preserved specimens would be to slit the skin and look at the shell. The shell of Species 1 is basically smooth, with some growth lines, while the shell of Species 2 is sculptured with spiral rows of shallow oval pits .... Bill Rudman.

Dall, W.H., 1919. Description of new species of Mollusca from the North Pacific Ocean in the collection of the United States national Museum. Proceedings of the U.S. National Museum, 56(2295): 293-371.

Gosliner, 1995. Introduction and spread of Philine auriformis from New Zealand to San Francisco Bay and Bodega Harbour. Marine Biology. 122: 249-255.

Habe, T., 1950. Philinidae in Japan. In: Illustrated Catalogue of Japanese Shells (Ed. by T.Kuroda), 7: 48-52.

MacFarland, F.M., 1966. Studies of opisthobranchiate mollusks of the Pacific Coast of North America. Memoirs of the California Academy of Sciences, 6: 1-546.

Mattox, N.T., 1958. Studies on the Opisthobranchiata: 2. A new tectibranch of the genus Philine. Bulletin of the Southern Californian Academy of Sciences, 57: 98-104.

Morton, B. & Chiu, S.T., 1990. The diet, prey size and consumption of Philine orientalis (Opisthobranchia: Philinidae) in Hong Kong. Journal of Molluscan Studies, 56: 289-299.

Rudman, W.B., 1970. A revision of the genus Philine in New Zealand with descriptions of two new species (Gastropoda, Opisthobranchia). Journal of the Malacological Society of Australia 2(1): 23-34.

Rudman, W.B., 1972a. Structure and functioning of the gut in the Bullomorpha. (Opisthobranchia) Part 3. Philinidae. Journal of Natural History 6(4): 459-74.

Rudman, W.B., 1972b. The genus Philine (Opisthobranchia, Gastropoda). Proceedings of the Malacological Society of London, 40(3): 171-87.

Willett, G., 1944. New species of mollusks from Redondo, California. Bulletin of the Southern Californian Academy of Sciences, 43: 71-73.

Bill Rudman.

Thanks for the photos, which appear alongside ... Bill Rudman

Dear Michelle
Look forward to getting the photos. I will be happy to post any information you and your students get on Philine. I am glad the Sea Slug Forum has led to you making more contacts for your research. I don't post all the "thankyou" letters I have received but clearly what is appearing on the site is only a fraction of the action that is being generated. At present we are receiving between 100-120 visits per day to the site. Good luck with your research ... Bill Rudman

Dear Michelle, Yes I would very much like to have photos to add to the site. Send them which ever way is easiest for you. If you send scans could you try and scan them so they are 300 pixels wide. This will avoid us having to resize them and possibly affecting their clarity ... Bill Rudman

Your questions take me back to some of the first research I did on opisthobranchs in New Zealand. You seem to have found my published papers on Philine ( Numbers 5, 15, 16) in my list of publications.

For background information, philinids are bubble-shells which have specialised for burrowing through sand and mud. They have a very stream-lined body and the shell is reduced to a thin internal plate-like shell in the back "posterior shield" region of the body. In the photo above it covers the brownish digestive gland. The bright white region is the muscular gizzard which contains three large calcareous plates which are used to crush the shells of the bivalves it feeds on. Species of Philine show an interesting evolutionary progression through species with small chitinous plates to species like Philine angasi which has two huge calcareous plates and a small third plate. Philine auriformis has three identically shaped plates.

My main aim was to compare the functional anatomy of various common bullomorph or cephalaspidean opisthobranchs. We knew little about the biology of any species then and unfortunately there are still major gaps in our knowledge. I don't know of any subsequent studies in New Zealand on Philine auriformis. To answer some of your specific questions:

•As a burrower it is seldom seen unless you are specifically studying it. I remember digging up and seiving huge areas of sandy mudflats in search of Philine and being happy to find 8 or 9 specimens per low tide. The only subtidal records I know of are from dredge samples, the deepest to about 12 fathoms (=72 feet, = 22 meters), but that could be because that is the limit of small naturalist dredge operations. So I can't say what its natural limits are.
•Again I can't be sure how deep it burrows but in most substrates I sampled the sediment became anoxic below about 10 to 15 cms and neither Philine nor its food Nucula were found in such conditions. I am not an expert on nuculid bivalves but Nucula hartvigiana is very common close to the surface in the top couple of centimetres. It is found in fine muddy sands of estuaries and coarser sands of more open beaches.

•The jelly-like egg masses of Philine are about 2 centimetres long, and are anchored in the sand by a long thread. The individual eggs are arranged inside the egg mass in a coil.
•I know of no predators of Philine auriformis but at times the aglajid bubble-shell Philinopsis taronga, a well-known predator of bubble-shells, was commonly found in the same area. Perhaps in California such spectacular aglajids as the huge Aglaja inermis (Navanax) could be feeding on this antipodean invader.

It seems this work would be an excellent excuse to apply for a grant to study these animals in New Zealand.

A good reference is: Gosliner, T. 1995. The introduction and spread of Philine auriformis (Gastropoda: Opisthobranchia) from New Zealand to San Francisco Bay and Bodega Harbor. Marine Biology, 122: 249-255.

A summary of the invasion story has been prepared by Terry Gosliner .. Bill Rudman