The identity of various named species or subspecies in the Mytilus edulis group is problematic.  For example, diegensis is synonymized with galloprovincialis by Coan et al. on the assumption that galloprovincialis was already introduced and firmly established in California by the time that Coe described this form.  However, one of the morphologically galloprovincialis-like specimens from British Columbia or the northwest U.S. examined by Ellen Rice Kenchington et al. for 18S DNA sequence came out as rather distinct from the others, and they speculated that it might have been diegensis, viewed as a valid regional endemic.  (She got married about when the paper was published, and I do not immediately remember whether it was published under Rice or Kenchington.) On the other hand, 18S is a very slowly evolving gene, and minor experimental error or slight individual aberration on the part of one galloprovincialis would be enough to give such results.  Data for more rapidly evolving genes would be more definitive.

The South American forms are even more problematic.  On the one hand, mussels could easily be transported on ships and accidentally introduced; on the other hand, Mytilus appears native to Australia (but not South Africa) as well as to the Northern Hemisphere.  The presence of mixed native and introduced species in many regions makes a large sample size necessary to address this problem with confidence.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa