Echiura

Cutlereb at aol.com Cutlereb at aol.com
Wed Oct 27 15:59:49 EST 1999


Dear Colleagues - 

   Here's a shared point of view about:
      Echiura: Phylum, Family(ies) or ??

	We three, who have some 'hands-on' experience with Echiura would 
like to share our perspective, in this informal context, on the issue of 
'proper' taxonomic rank for this group of worms.  Our intent is to open the 
idea that either to maintain it as a phylum MAY be wrong, but to consider it 
as a single family COULD BE equally wrong.  

	The problem may concern the separate issues of "clustering" and 
"ranking".  If the echiuran worms are proved non-monophyletic, we might 
well claim two or more families for this animal group.  On the other hand, IF 
the worms are proved to constitute a monophyletic group, its ranking may 
be dependent on the reconstructed tree; the family rank might be also 
possible in the system of Annelida.   

	It is our judgement that to reduce it to a single Family based on the 
currently available information, is premature.  At the very least, if one is 
going to base this judgement on molecular data, we must look at a 
representative of the bonellids, a major sub-set, and one with distinctive 
sexual dimorphism.   

	It is in some ways unfortunate that the morphologically unique genus 
Urechis (4 putative species each in its own corner of the Pacific) is so 
easy to obtain because it is the only genus in its Order & Family - a 
derived taxon whose molecular (and developmental?) attributes may not be 
an accurate representation of the larger group.   

	Thus, in our minds the questions of number of higher taxa as well as 
rank remain open. It is our opinion that a richer, more convincing database 
is needed to support clustering these within the Annelida, and to more 
firmly establish the number and rank of such group(s). We adopt this more 
conservative position partly to avoid serial changes in the system that we 
know are not well appreciated by our non-taxonomist colleagues.  

     Regards,
         T. Nishikawa, J. I. Saiz-Salinas, E. Cutler

-----------------------------------------------------------------------
Teruaki Nishikawa, D. Sc.
Graduate School of Human Informatics,  Nagoya University,
Chikusa-ku, Nagoya 464-8601, JAPAN
E-mail: teruaki at info.human.nagoya-u.ac.jp

Dr. José I. SAIZ SALINAS                    
Dpto. de Zoología y DCA                  
Univ. País Vasco                         
E-48080 Bilbao, Apdo. 644  SPAIN                                    
E-mail: zopsasaj at lg.ehu.es    
http://www.fauna-iberica.mncn.csic.es/faunai/cvi/salinasi.html                
 

Edward B. Cutler, PhD
Department of Invertebrate Zoology,  Museum of Comparative Zoology
Harvard University,  Cambridge, MA   02138,  USA
e-mail:  CutlerEB at aol.com
http://www.mcz.harvard.edu/Departments/InvertZoo/as.fldr/cutler/cutler.htm


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