Re: New papers in Geobios (and nomenclatoral gripe)

[gerarus@westnet.com.au]

---- Original Message ----
From: twilliams_alpha@hotmail.com
To: dinosaur@usc.edu
Subject: Re: New papers in Geobios (and nomenclatoral gripe)
Date: Tue, 20 Jun 2006 08:59:22 -0500

>I respectfully disagree.  If a species is declared to be a nomen
>dubium, 
>then this species has no taxonomic standing whatsoever.  

    This is simply not true. The recognition of a taxon as a _nomen
dubium_ is a subjective, not objective, decision. Nomina dubia retain
full taxonomic availability, though they may not currently be
practically usable.

If the
>species in 
>question is the type species for a genus, then this genus is also
>invalid.

    If the taxon can still be diagnosed at the genus level, then
there is no reason why the genus should be invalid. In the case of
the genus _Pantopsalis_ (Arachnida, Opiliones) that formed a large
part of my Master's thesis, the type species _P. listeri_ can't
currently be identified at species level due to the necessary
characters not being in the original description (and the type
material is possibly lost). However, the written description supplies
enough detail that I can be sure that it was indeed a _Pantopsalis_,
and can still use the genus as it currently stands with confidence.

>However, the type material for a nomen dubium may be diagnostic at
>the genus 
>level.  

    Then if the _nomen dubium_ is type of a genus, then it may be the
appropriate name of the genus that it can be identified to.


If _Mochlodon suessi_ is not diagnostic at the species level,
>then 
>_M. suessi_ is a nomen dubium; and if _M. suessi_ is the type species
>for 
>_Mochlodon_, then _Mochlodon_ is an invalid genus.  But if the type
>material 
>can be referred to another genus (i.e., one that is valid), its
>generic 
>identity can be indicated as "_Zalmoxes_ sp." (as in this case).

    If _Mochlodon_ can be identified at genus level, then _Mochlodon_
is the appropriate name for a genus, whether its type species can be
identified at species level or not.

>There are other examples similar to the _Mochlodon_ situation. 
>Carpenter 
>(1990) regarded _Denversaurus schlessmani_ as a nomen dubium,
>although he 
>found the type material to be referrable to _Edmontonia_, as
>_Edmontonia_ 
>sp.  He did not create the new combination _Edmontonia schlessmani_,
>because 
>the characters used to define the species _Denversaurus schlessmani_
>were 
>invalid.

    But if _Denversaurus_ had priority over _Edmontonia_, then it
would become the appropriate name for the genus. If _Denversaurus_
does not have priority, then that example is not relevant to the
argument at hand. (Because genus- and species-level names are not
concordant in the ICZN, there are no requirements for publication of
new combinations - in contrast, offhand, to the ICBN).

    Ka kite,

        Christopher Taylor