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Re: New papers in Geobios (and nomenclatoral gripe)
Christopher Taylor wrote:
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
I agree that the recognition of a taxon as a nomen dubium is subjective.
For example, there are names that have been revived as valid genera or
species after previously being declared nomina dubia. But although a nomen
dubium is taxonomically available, its status as a nomen dubium (or nomen
vanum) removes it from taxonomy for all practical purposes.
Having a species declared a nomen dubium means that the species cannot be
diagnosed at the level of species. If the species in question is the type
species for a genus, then that genus is invalid as well. A genus is only as
good as its type species. This may seem a little unfair, as the genus may
otherwise be very well known and/or include species that are indisputably
The only way to bypass this situation is to designate a new type species, as
was done with _Iguanodon_. The original type species (_I. anglicus_) was a
nomen dubium, which technically made _Iguanodon_ a nome dubium too. But the
ICZN allowed a new type species to be designated (_I. bernissartensis_),
which 'rescued' the genus _Iguanodon_ from oblivion. If your premise was
correct (i.e., a genus is valid even if the type species is specifically
non-diagnostic), then we would not have had to go to all this trouble for
If the taxon can still be diagnosed at the genus level, then there is
no reason why the genus should be invalid.
Unfortunately, having an invalid type species is one reason why a genus can
be taxonomically invalid.
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. [snip]
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.
I wondered about this... but again I cannot see how _Mochlodon_ can be valid
without _M. suessi_ also being valid. The validity of _Mochlodon_ is
predicated upon _M. suessi_ (its type species) not being a nomen dubium. If
_M. suessi_ can be demonstrated to be synonymous with one of the _Zalmoxes_
species, then _Mochlodon_ is back in the game, and it would have priority
over _Zalmoxes_. But as a nomen dubium, the name _M. suessi_ is limited to
the type material; further material cannot be referred to it, and it cannot
be referred to another species or genus.
All is not lost for _Mochlodon_. If the two current _Zalmoxes_ species (_Z.
robustus_, _Z. shqiperorum_) are shown to be synonymous AND _M. suessi_
belongs to the same genus as _Zalmoxes_, then _Zalmoxes_ becomes a junior
synonym of _Mochlodon_. This is because the characters previously use to
diagnose the genus are now the same as those used to diagnose a single
species, and so _M. suessi_ would become specifically diagnosable.
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 CBN).
I brought up this example, because of Mickey's argument that _M. suessi_ is
referrable to the genus _Zalmoxes_. As he put it:
"If Mochlodon suessi's holotype is referrable to Zalmoxes but not
specifically diagnostic, there should be three species of Mochlodon - M.
robustus, M. shqiperorum and M. suessi. The latter could be the holotype yet
still be specifically indeterminate."
But a species that is specifically indeterminate cannot be a valid species
in ANY genus. In this respect, _Denversaurus schlessmanni_/_Edmontonia_ is
analogous to _M. suessi_/_Zalmoxes_.
I hope some of that made sense.