[Taxacom] Use of geographic range data as diagnostic characters

[Doug Yanega]

Derek wrote:

>It seems the code has some constraints on what constitutes a valid
>character, but is not exhaustive and I remain unconvinced that it
>explicitly forbids reliance on locality as a diagnostic trait to establish
>a new taxon.  I do hope to be proven wrong on this point!

and Francisco responded:

>This discussion suggests that it would be useful to include a note in the
>Glossary's definition for "character" to exclude a locality to be
>interpreted as a character. Maybe also in Art. 13.1.1 an additional note
>in this sense could be helpful to have a clear guideline.
>
>There is a general rule in the Code that the younger the date, the
>stricter the rules. So from this point it is logical that if a locality is
>not allowed to be interpreted as a description for names before 1931, much
>less will it be for names after 1930.

In a way this is second-guessing what was already a correct response 
(from my perspective). Specifically, the terminology used in Arts. 
12.3 and 13.1.1 are *intended* to be taken together, and I believe 
12.3 does constitute an explicit prohibition of locality data.

Since it was cited ealier in the thread, I'll re-cite it:

>  >> Art. 13 talks about names established later and is even more explicit in
>>>  its Art. 13.1.1 where is said "a description or definition that states
>>>  in
>>>  words characters that are purported to differentiate the taxon".
>>>
>>>  >
>>>  > ICZN:
>>>  > 12.3. Exclusions. The mention of any of the following does not in
>>>  itself
>  >> > constitute a description, definition, or indication: a vernacular
>>>  name,
>  >> > locality, geological horizon, host, label, or specimen.

It is not as important to focus on what the Code means by 
"characters" as it is to focus on what it means by "description or 
definition". In other words, the key clause in 13.1.1 is that there 
must be a "description or definition" and 12.3 gives a list of things 
which are explicitly NOT, in and of themselves, to be interpreted as 
"a description, definition, or indication". None of the items listed 
in 12.3 can be used to satisfy 13.1.1 (and, giving the same exact 
list under Article 13 would be entirely redundant). Accordingly, my 
interpretation is that even though some of the items in 12.3 could be 
used as diagnostic aids (namely locality, host, and geological 
horizon), they cannot satisfy 13.1.1, because something *else* must 
be used to create a "description".

For those who insist on rewording the glossary for clarification (and 
if this is being forwarded to Gary for the wiki), I would offer the 
following as an appropriate and objective definition of "character":

"Any property of a taxon that can be objectively derived and 
evaluated via direct examination of individual specimens belonging to 
that taxon; i.e., without recourse to external sources of 
information, such as labels, photos or illustrations, maps or field 
notes, isotope dating, statistical analyses, or phylogenetic trees."

Note that this definition would also exclude all of the items 
excluded under 12.3, while including gene sequences. Perhaps the one 
contentious item - and I would strongly defend it - is the exclusion 
of anything that is statistical in nature. Lest this be 
misinterpreted, something like (e.g.) "wing length 12.2-15.7 mm" 
would be a character, because it is descriptive, and an individual 
specimen could (during a diagnostic process) be evaluated as to 
whether it does or does not comply with the specifications for that 
feature. However, something like "mean wing length 13.6 mm" would NOT 
be a character, because it is not a property that can be evaluated 
for an individual specimen, but only for a *group* of specimens.

Sincerely,
-- 

Doug Yanega        Dept. of Entomology         Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314        skype: dyanega
phone: (951) 827-4315 (standard disclaimer: opinions are mine, not UCR's)
              http://cache.ucr.edu/~heraty/yanega.html
   "There are some enterprises in which a careful disorderliness
         is the true method" - Herman Melville, Moby Dick, Chap. 82