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Siboglinid paper

Kenneth M. Halanych khalanych at whoi.edu
Thu Aug 30 18:04:23 EST 2001

A paper on Siboglinid phylogeny just came out in Biological Bulletin.  I 
mention it to the Annelid list because Siboglinids are a good case where 
morphology and molecules agree. A recent paper by Greg Rouse using a 
morphological cladistic analysis and the paper by Halanych et al. (using 
16S rDNA and 18S rDNA) reach similar conclusions.  

A pdf for the Halanych et al. paper is available from Biological Bulletin, or I 
can be contacted at the address below for reprints. 

Halanych, K. M., R. A. Feldman, and R. C. Vrijenhoek. 2001. Molecular 
evidence that Sclerolinum brattstromi is closely related to vestimentiferans, 
not frenulate pogonophorans (Siboglinidae, Annelida). Biol. Bull. 201:65-

Rouse, G. 2001. A cladistic analysis of Siboglinidae Caullery, 1914 
(Polychaeta, Annelida): formerly the phyla Pogonophora and 
Vestimentifera. Zoological Journal of the Linnean Society 132(1):55-80 


Abstract. Siboglinids, previously referred to as pogonophorans, have 
typically been divided into two groups, frenulates and vestimentiferans. 
Adults of these marine protostome worms lack a functional gut and harbor 
endosymbiotic bacteria. Frenulates usually live in deep sedimented 
reducing environments, and vestimentiferans inhabit hydrothermal vents 
and sulfide-rich hydrocarbon seeps. Taxonomic literature has often treated 
frenulates and vestimentiferans as sister taxa. Sclerolinum has traditionally 
been thought to be a basal siboglinid that was originally regarded as a 
frenulate and later as a third lineage of siboglinids, Monilifera. Evidence 
from the 18S nuclear rDNA gene and the 16S mitochondrial rDNA gene 
presented here shows that Sclerolinum is the sister clade to 
vestimentiferans despite lacking the characteristic morphology (i.e., a 
vestimentum). The rDNA data confirm the contention that Sclerolinum is 
different from frenulates, and further supports the idea that siboglinid 
evolution has been driven by a trend toward increased habitat 
specialization. The evidence now available indicates that vestimentiferans 
lack the molecular diversity expected of a group that has been argued to 
have Silurian or possibly Cambrian origins.  

Kenneth M. Halanych 
Biology Department 
MS 33 
Woods Hole Oceanographic Institution 
Woods Hole, MA 02543 


Phone: (508) 289-3565 
Fax:   (508) 457-2134

<khalanych at whoi.edu>

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