[Taxacom] PhyloCode & ICZN to "duke it out"?

Laurent Raty l.raty at skynet.be
Thu Oct 4 17:57:18 CDT 2007

Hi Rich,

First, note that I was not taking a definite position in favour of one
system or the other, either - in fact, I can certainly agree with a lot of
the concerns that PhyloCoders have against the Linnean system. I would
also certainly see no problem where the two systems do not overlap; the
problems are only where they do.

There is at least one thing with which can't fully agree (and that may be
crucial, actually) :

> There is NO content definition for Linnaean names under the existing
> Codes. In fact, this is probably the main reason why the authors of the
> Phylocode felt a need for a new system in the first place (that, plus
> the ranks problem when mapping nomenclatural hierarchy to clades).
> Linnaean names are anchored to a single "type", and thus have no defined
> scope of content.

Although the content associated to a valid Linnean name is indeed not
defined, it is NOT free to be extended at will either; it is, in practice,
directly limited by the Principle of Priority. A name cannot validly apply
to a taxon that includes the type of any older name of the same group.

If you think taxa should be monophyletic, which as you say most taxonomists
do in practice, this results in the Linnean system being very densely
filled with implicit phylogenetic constraints, that are like stem-based
definitions of the maximum scope of each name. The PhyloCode definitions do
not (and probably could not) integrate all these constraints.

Well, it's late here too ;-),
Laurent -
Laurent Raty
l.raty at skynet.be
Brussels, Belgium

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