[Annelida] Nemertean taxonomy – time to change lane?
(by g.read from niwa.co.nz)
Mon Sep 12 00:34:25 EST 2011
The point of view in these 2 items might be of interest if you have
ever been asked to identify a dead nemertean. However, as with
particular polychaete groups lacking much external diversity in
features, the impediment to quick progress probably will continue to be
the overall lack of ethanol-fixed material.
Sundberg, Per; Strand, Malin. 2010. Nemertean taxonomy – time to
change lane? [letter]. Journal of Zoological Systematics and
Evolutionary Research 48(3):
Strand, Malin; Sundberg, Per. 2010. A DNA-based description of a new
nemertean (phylum Nemertea) species. Marine Biology Research 7(1):
63-70 Abstract: Nemerteans (Nemertea) are traditionally
described from internal characters obtained from histological sections
of serially sectioned animals. The procedure is time-consuming and
requires careful preparation of specimens. The preparations often suffer
from artefacts caused by the handling of the animals, since they
contract extensively when fixed. It is commonly stated that nemerteans
can only be reliably identified using internal characters and the taxon
is therefore viewed as ?difficult? and, as such, often overlooked in
e.g. marine inventories because nobody has the time, facilities or
skills to do the sectioning. Contrary to this often-stated ?fact?, our
experience is that many nemerteans can be identified from external
characters, although there of course are exceptions. The risk for
fixation artefacts in combination with an ascertained high (natural?)
intraspecific morphological variation make us pose the question whether
anatomy is in fact the best and most efficient basis for phylogeny and
classification. There is undoubtedly a large number of
undescribed/unnamed nemerteans. To cope with this, we pragmatically
propose that nemerteans can be described by a combination of external
characters and DNA sequences. We apply this concept on one recently
found species new to science, Pseudomicrura afzelii gen. et sp.
Neither article is open access, so for copies contact Per Sundberg
(p.sundberg from zool.gu.se).
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