Philine auriformis?
Species 2 from California.

Family: Philinidae


This is one of two species of Philine recently introduced to California from an unknown source. Initially both were identified as Philine auriformis but we now know there are at least two species present, and it unlikely that either is Philine auriformis.


UPPER: Shell and gizzard plates of a specimen sent by Michelle Chow from Bodega Bay, California, July 1998. Scale is 10mm. PHOTO: Bill Rudman.

MIDDLE: SEM photo of inner radular teeth on left side. PHOTO: Alison Miller.

LOWER: SEM photo showing two of the reduced outer teeth on right side. PHOTO: Alison Miller.


Philine in California

Specimens of this species were described by Gosliner (1990) and identified with Philine auriformis from New Zealand. Despite my initial suggestion to the contrary, (See July 30, 1998 message below) the anatomy of this species is as described by Gosliner. However although the basic "plumbing" of the penis is the same in both New Zealand and Californian specimens, the relative size of the penial complex, as illustrated below, is quite different, that of Californian specimens being much smaller. It is possible that the specimens from California I looked at were immature, but if so, they are larger than most mature New Zealand specimens. I have also shown below that the radular teeth of New Zealand specimens are half the size of Californian specimens. This quandary only emphasises the need for more research on the anatomy of the many species of Philine that have been described on shell alone.

Authorship details
Rudman, W.B., 1998 (August 10) Philine auriformis? Species 2 from California.. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

The identity of Californian Philine auriformis

August 10, 1998
From: Bill Rudman

Realizing that there could be no satisfactory conclusion to the Californian Philine identity crisis until specimens from New Zealand could be re-examined, I searched through old material I had brought to Sydney many years ago and found 3 specimens of Philine auriformis, one of which was well enough preserved to re-examine the reproductive system. I have therefore compared two specimens from Bodega Bay directly with the New Zealand specimen and with dissection notes from material I examined years ago in New Zealand. Two very significant anatomical features were quickly apparent which suggest to me that Californian specimens are not Philine auriformis.


Comparison of Philine auriformis, from Stewart Is, New Zealand (LEFT), and specimens from Bodega Bay, California (RIGHT).
Shell height = 6mm. Gizzard plate length = 5mm (in both cases).

UPPER: Penis complex. (scale = 1mm)
in = incurrent sperm duct., ej = ejaculatory duct., pr = prostate gland.

LOWER: Whole radula. (scale = 1mm)

Fortunately I was able to compare specimens from California and New Zealand of the same size, as measured by the length of the shell (6mm in each case) and gizzard plate length (5mm in each case) which solved the potential problem of comparing sizes of preserved animals, possibly contracted to different degrees.

PENIS ANATOMY: Although the basic "plumbing" of the penial complex was the same, the proportional size of the prostate gland and ejaculatory duct are quite different. In the Californian species the ejaculatory duct is very short and the prostate gland forms a tightly tangled mass which sits betwen the straps of longitudinal muscle on the floor of the body cavity. In New Zealand animals the penial complex is much larger lying over the whole floor of the anterior part of the body cavity. The prostate gland forms a large mass of loosely coiled duct.

RADULA: There are no clear differences in shape of individual teeth between New Zealand and Californian specimens. However the radula and individual teeth of New Zealand specimens is only half the size of Californian animals of the same size.

These two species have been confused because we have so little information on the anatomy of the genus. In shell and gizzard plate size and shape they are very similar. In radular tooth shape they are very similar, and in penial plumbing they are also very similar. However the quite different tooth size and the proportional differences in the prostate gland and ejaculatory duct are real differences which need to be considered. ... Bill Rudman

Rudman, W.B., 1998 (Aug 10). Comment on The identity of Californian Philine auriformis by Bill Rudman. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

On Philine

July 30, 1998
From: Bill Rudman

[NOTE inserted Aug 5: The information here on penis structure is wrong. See correction . .. Bill Rudman.]

This is one of two species of Philine which have "invaded" California recently. They have been mistakenly identified with the New Zealand species Philine auriformis. A discussion on this is found elsewhere in the Sea Slug Forum.

This unidentified species which I have labelled SPECIES 2 has the following main characters:

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 with a large inner tooth on each side of the midline, flanked by an outer reduced 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 photos and drawing on the right are from specimens sent by Michelle Chow from Bodega Bay, California, July 1998.
UPPER LEFT: 2 shells, the larger being slightly damaged on the outer edge (Scale 10mm). UPPER RIGHT: Penis and prostate gland from animal 23mm long preserved (shell 13mm).
MIDDLE: Shell sculpture.
LOWER: Outer side of gizzard plates (Scale 10mm).
PHOTOS: Bill Rudman.

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 Californian Species 1 (which I tentatively identify as Philine orientalis) 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.

Bill Rudman.

Rudman, W.B., 1998 (Jul 30). Comment on On Philine by Bill Rudman. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from