Nereis

[110275.1004 at compuserve.com]

Dear Fredrik et al,

Well, I can't argue cladistics but I have been taking a hard look at the
Nereididae and the Nereis/Neanthes/Hediste group in particular. 

Traditionally, we have focused on setae and paragnaths in describing 
these species and genera.  Unfortunately, the numbers of paragnaths 
appear to be related to environmental conditions, particularly salinity.  
Looking at the STRUCTURE of the parapodial lamellae, on the other 
hand,  is extremely illuminating:  Neanthes has a complex series of lobes 
and folds surrounding the supra and sub-acicular bundles (interference 
phase contrast needed, SEM helpful).  Nereis has just a couple of simple 
lobes. Hediste is more like Nereis in this regard but does have those 
homogomph falcigers in the posterior neuropodia.  More, it seems to 
comprise a very morphologically similar set of sibling/cryptospecies from 
euryhaline/freshwater littoral zones.   

More research is needed but I am convinced it will bear out the 
separation of these genera.  Part of the problem seems to the extreme 
"familiarity of the Nereididae:  they are among the most common and 
most frequently encountered polychaetes in shallow zones along the 
coast (where most marine research is concentrated).  We all "know" 
what they look like.  A really hard look might bring up some major 
surprises, but will likely not end the controversy.  

Judy Fournier
<110275.1004 at compuserve.com>


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