If there is one objective fact which can be gleaned from our discussion of
speciation/subspeciation, it is that taxonomy remains the most subjective of
all sciences.  Sometimes we tend to forget this.  Too often we approach the
question "is this a species or a subspecies?" the same way a chemistry
student might ask  "is this a compound or an element?".  We expect an
objective, definitive answer.  We act as though a species is something that
objectively exists in nature, like a chemical element.  - something
precisely defined and therefore readily identifiable.  In fact, what exists
in biological nature is simply diversity.  Taxonomic concepts like species,
genus, family, order, class and phylum exist in the human mind, not in
nature as such.  Such a system represents an effort by our species to
categorize the vast array of biological forms on earth in a way that enables
us to think about them in a more logical and meaningful way.  Such a system
is of human origin, and humans do their best to apply it, as efficiently as
possible, to an endlessly variable and ever changing reality.  This is far
different from the precise natural order of chemical elements for example,
which exist in nature, de facto, precisely defined by unalterable intrinsic
properties, subject to human discovery but not dependent on any human action
for their identity.  In other words, an element is an element whether a
human ever recognizes it as such or not - but a species is a species only
because we say it is.  Regarding the recent discussion of Cymatium species -
Cymatium martinianum was classified as a subspecies of Cymatium pileare.
Now it is considered a distinct species.  One might naturally be tempted to
wonder which classification is the "correct" one - however, doing so ignores
the subjective nature of taxonomy.  Cymatium martinianum was, IN FACT, a
subspecies of Cymatium pileare.  Why?  Because we said it was.  If the
reclassification is generally accepted, then Cymatium martineanum is now, IN
FACT, a full species, for exactly the same reason.  It is important to note
that neither classification was/is "wrong", since such classifications are
subjective in nature - essentially matters of opinion - which is why we can
get frustrated if we approach them as matters of objective fact.  This is
not to say that taxonomists don't use objective criteria in making such
decisions.  They do, of course - but which objective criteria to use, and
how to apply them, are subjective decisions, which is why there will never
be full agreement as to what exactly constitutes a species or subspecies.
Paul M.