June, 1999 
SCAMIT Newsletter 
Vol. 18, No. 2 
We then compared a couple of acrocirrids of 
Cheryl Brantley’s from 2 stations in Bight’98 
with a few of Rick Rowe’s from San Diego’s 
ITP survey. Cheryl found a total of 5 
specimens from station 2490 (75 m) west of 
San Miguel Island and 2 specimens from 
station 2491 (95 m) also west of San Miguel. 
Rick’s were from 63 ft and 171 ft both near the 
Mexican border. Despite Cheryl’s specimens 
being a little larger they seemed to be the same 
species. They most closely fit Hartman’s Atlas 
description for Acrocirrus crassifilis Moore 
1923 except the notosetae were serrated and 
started on the same setiger as the neurosetae. 
Also, the small papillae on the ventrum didn’t 
appear to be in exact rows, but more scattered. 
A. crassifilis was described from much deeper 
water, 400- 600m. Rick had a partial voucher 
sheet already done on these acrocirrids. He will 
finish the sheet and distribute it to SCAMIT 
members. The unknown acrocirrids will be 
referred to as Acrocirrus sp SD1. 
CAN’T DODGE THIS BULLET 
Over the past two decades it has become 
increasingly apparent that the European edible 
mussel Mytilus edulis, which was routinely 
reported from the Pacific coast in popular 
accounts, in monitoring studies, and in the 
scientific literature, is not that species. At least 
two other species are known to occur on the 
Pacific coast (McDonald & Koehn 1988, 
Koehn 1991), both routinely identified as M. 
edulis until recent years. We have not had 
reason to be too concerned with this change, as 
POTW monitoring efforts normally do not 
encounter any species of Mytilus in their 
community sampling. B’98 samples 
specifically targeted areas frequented by 
mussels, however, and Mytilus were taken by 
several of the participating agencies. We finally 
have to consider how to differentiate the three 
species Mytilus edulis, M. galloprovincialis , 
and M. trossulus [as well as their hybrids] 
where they occur along the Pacific coast of 
North America (see distributional information 
in McDonald et al 1991, and Suchanek et al 
1997). 
The most definitive methods are DNA 
analyses or allozyme analysis of tissues from 
each mussel (Comesana et al 1999), but this is 
both prohibitively time consuming and 
expensive in a non-research context. Several 
authors have proposed and attempted to apply 
morphometric characters to separate the 
species where they co-occur (McDonald et al 
1991; Seed 1972, 1974; Gardner 1996; Kepel 
& Ozolinsh 1992). 
Those members with an interest in Mytilus 
identifications should acquire and digest the 
above publications. We will attempt to deal 
with the issue when we can schedule a meeting 
with Paul Valentich Scott on bivalves. By that 
time we should all be prepared with specimens, 
literature, and experience in applying the 
suggested morphological descriminators. Until 
then we’re on mussel watch, and we should 
probably refer to them as Mytilus sp in our 
data. Those of you who have a number of 
Mytilus to identify, and/or who have mixed lots 
with more than one of the species should 
speciate them as best you can, but make sure 
you keep a record of the separatory criteria 
used for later consideration. 
POLYCHAETES PLUS 
During the nemertean meeting at the Santa 
Barbara Museum of Natural History in 
February long-time member Sue Williams 
joined us for the first time in some years. She 
has been busy in the interim, mostly 
concentrating on education related work, 
although occasionally continuing her 
consulting work. She would be happy to renew 
old contacts and make new ones, although 
she’s not eager to leave Ventura to venture onto 
the L.A. Freeways. Her work in recent years 
has extended her interests far beyond 
polychaete taxonomy into wetland ecology and 
even to intertidal insects. It was great to see her 
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