[Taxacom] Fwd: complete list of all species
m.j.dallwitz at netspeed.com.au
Fri Feb 15 07:11:59 CST 2008
Paul van Rijckevorsel wrote:
> * the type determines what the name is attached to
> * the circumscription defines the taxonomic boundaries
> * a description (or a set of descriptions) of a taxon is only possible
> and meaningful when its circumscription is established.
In a sense, descriptions must come first. The taxonomist derives the
circumscriptions by analyzing descriptions of lower taxa or specimens. This
may be done in the mind, or with aids such as a computer.
However, this is irrelevant to the point I was trying to make. If others are
to make use of the concept and the associated name, the taxon must be
adequately, accessibly, and reproducibly described. The type is a legalistic
concept of little or no scientific value.
> I would guess that the main reason for failing identifications would
> be the absence of good pictorial material.
The failures are due to characters that are poorly defined and/or poorly
communicated. Illustrations are often important, but their absence is not
necessarily the main problem.
One problem is character 'states' that are not mutually exclusive. No matter
how well you communicate the meaning of such 'states', they will inevitably
lead to errors in identification.
Explanatory notes and images should be prepared, and the characters tested,
_before_ substantial amounts of data have been recorded, not as an
afterthought just before publication. The testing should be done by having
several people record data for the same taxa, either by recording all the
data again, or by doing identifications from the data. Students might
benefit from participating in this, and volunteers might find it interesting.
Testing by identification should continue throughout the development of the
data. Checking descriptions generated from the data is not sufficient to
ensure reproducibility: you might be confident that the description is
correct, but be unable to reproduce it independently, which is what is needed.
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