October, 1999 
SCAMIT Newsletter 
Vol. 18, No.6 
preservation. A second species of runcinid, 
Runcinida sp., has been taken in intertidal and 
subtidal coralline algal scrapings from San 
Clemente Island. It can easily be differentiated 
from R. macfarlandi by the nature of the gills. 
In Runcinida there are five gills which arch 
over the anus. Each has both a primary 
lamellus and secondary lamellae. The animals 
are otherwise similar in size and general 
appearance. 
A different species of small aeolid, Cuthona sp 
A, was found at the same station. It is 
probably introduced, perhaps from Japan (Don 
will continue to try and tract it down). This 
small animal was characterized by conservative 
(remaining after preservation) dark pigment 
patches in the ceratal cores, and on the sides of 
the body, which do not match any of the 
species in the genus reported locally. It also 
displays the rounded head, thin finger-like 
anterior foot corners, and long simple 
rhinophores usually seen in these animals. The 
radula was unlike that of any other local 
Cuthona as well, having accessory spikes along 
the lateral edge of the tooth just above the base 
(one on each side). The radular formula is 0-1- 
0, as it should be for a Cuthona , and each tooth 
has 5-7 lateral denticles(depending on position 
in the ribbon), and a pair of smaller accessory 
denticles flanking the central cusp, which is 
slightly shorter than the laterals. Ron thought 
that it had also been seen in San Diego Bay, but 
would have to check. 
The pending, heavy problem of the afternoon 
finally surfaced when it could no longer be 
avoided - Mytilus. In the past we have been 
able to avoid this issue since mussels of this 
genus did not occur in our benthic samples 
from offshore. When B’98 samples from 
within harbors were processed however, we 
were confronted with specimens forcing us to 
address the question of mussel speciation. John 
Ljubenkov started with a review of the three 
species that could potentially be found locally, 
M. trossulus, M. galloprovincialis, M. 
californianus and briefly covered the 
morphological differences he thought could be 
used to separate them. Mytilus californianus 
can be separated from the other two based on 
it’s surface ribbing. John and Don Cadien had 
previous examined a series of small specimens 
from offshore platform legs, and thought they 
had a method of separating them into two 
discrete taxa. However, John found in 
examining another fraction of the same sample 
that as the animals got larger the character lines 
between presumptive M. trossulus and M. 
galloprovincialis started to blur. He had 
brought a large size range of animals collected 
from the legs of an oil platform off Santa 
Barbara, CA., and although some animals 
looked somewhat different it would have been 
difficult to separate them reliably and 
consistently. We are not the first group to 
stumble across this problem and did not 
actually come up with any definitive answers 
or solutions at this meeting. The problem was 
laid before us as food for thought and will re¬ 
surface at another meeting, perhaps one 
devoted entirely to that subject. 
At this point it was late in the afternoon and 
attention spans were drifting. Unfortunately, 
crustaceans had not been covered and there is 
plenty of material in that phyla that needs to be 
addressed, therefore it was decided that the 
next non-polychaete meeting will be devoted to 
crustaceans. The meeting is scheduled for 
November 15 and will be at the City of San 
Diego. 
WWW NEWS 
The SCAMIT web-site is cruising along nicely, 
thank you. After our remodeling earlier this 
year we have settled in to the new look and feel 
of our site with little ado. Fortunately, others 
have noticed the improvements, and one 
appreciative visitor sent the following to 
Webmaster Jay Shrake:... “Dear Jay, I have 
browsed your SCAMIT web site today and 
agree with you that it should be linked into the 
NBII Biodiversity, Systematics and Collections 
web site. Yours is a very nice web site, easily 
9 
