James Blake jablake at
Sat Oct 2 15:40:20 EST 1999

Dear Folks,

I agree with Geoff in that we need to sort out the Capitella sibling species 
complex and apply names to go with the entities.  

In the soon to be published and last annelid volume (7) of the "Taxonomic Atlas
of the Santa Maria Basin Fauna....", I have attempted to set the framework for
the revision of Capitella that Geoff is talking about.

I review the recent taxonomic history including the classification schemes 
of Hartman and Warren, and where those schemes apply to the sibling 
species issues arising from the discoveries of Judy Grassle and others. I 
restrict Capitella capitata sensu lato to specimens having capillaries in 
both rami of setigers 1-6 and either capillaries, hooks, or mixed fascicles 
on setiger 7.  I present a table of six of the sibling species that Judy and 
others have studied and point out that four of these belong to this broadly 
defined definition. However, when one looks at the table, it will be very 
apparent that each of those four siblings can be readily separated from 
one another on the basis of prostomial shape, nature of the peristomium, 
shape of the posterior end, distribution of hooded hooks, and several of 
the reproductive and developmental features.  

Among the specimens I examined from California were three different 
morphotypes that fall into the "sensu lato" restriction I have suggested.  At 
least one of these is clearly sibling species I; I don't know if the other two 
belong to other defined siblings or are further new species.  However, the 
point is that I am able to distinguish what appear to be different species 
based on adult morphology alone.  One of these three has a distinct 
methyl green staining pattern, the others do not.  

What is needed is to acquire a collection of adult Capitella from Naples, 
the type locality and to establish and fix a definition of C. capitata from 
there. Once that is done, then the various siblings can be sorted out and 
named.  I have set up a matrix of what I have and run some preliminary 
cladistics and given the relatively large number of characters available, 
the resolution among the siblings is very good with at least one good 
synapomorphy at each branch. Therefore, I am quite confident that the 
group can be sorted out at some point and some names applied.  This 
really is quite crucial because C. capitata or whatever one calls it these 
days, is very important in coastal ecology and is sometimes used a test 
organism.  When that is done, it becomes a matter of comparing apples 
and oranges as far as comparative test results are concerned.  

I am probably not the one who will ultimately resolve this issue (capitellids 
are not my favorite worms), but it was interesting to pull this information 
together.  Hope this helps a little.  We are hoping to have vol. 7 in print 
before the end of the year.  Brigitte and I are just wrapping up our last 


James A. Blake
ENSR Marine & Coastal Center
89 Water Street
Woods Hole, MA 02543
<jablake at>

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