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Re: Taxonomy Question
Saint Abyssal a écrit :
> Is there a term that refers categorically to junior synonyms, nomena
dubia, lapsus calami, and all the other situations that cause scientists
to disregard genera and species? I've always called them "invalid taxa"
but technically that only applies to nomena nuda. I've considered
referring to them as "rejected" but that sounds like I mean a nomen
rejectum. Is there an actual term that I can use for non-accepted genera
A good question indeed, since the same terminology is often used to
designate the status of both taxa and nomina. We should first
distinguish "invalid nomina" and "invalid taxa". The status of a nomen
involves the International Code of Zoological Nomenclature (for an
animal): "invalid" refers here to the nomenclatural status of the nomen
and is objective. The status of a taxon, however, is independent from
that of the nomen. Its status is given by taxonomists who judge if this
taxon (i.e. the holotype/type species/type genus and hypodigm) is
Nomen: object => Nomenclatural status (objective).
Taxon: concept => Taxonomic status (subjective).
Synonymy => Taxonomy - except in the case of objective synonymy (same
holotype/type species/type genus) where it involves nomenclature.
Nomina dubia => Taxonomy.
Nomina nuda => Nomenclature.
Lapsus calami => Nomenclature.
Homonymy => Nomenclature.
In most papers, however, scientists say "taxon" when they mean
"nomen"... The difference is significant, though: an invalid taxon MAY
have a valid nomen, but a valid taxon MUST have a valid nomen. Also,
taxa invalidated by taxonomists should be distinguished from those
bearing an invalid name. Practically, we could call these cases:
nomenclatural/taxonomic validity, or subjective/objective validity.
A nomenclaturally invalid taxon would thus bear a nomen nudum, but a
taxonomically invalid taxon could bear a nomen nudum or a nomen dubium,
or any nomen following the rules of the ICZN.
Let's take for example:
> The Spanish sauropod taxon Galveosaurus:
Its holotype was described independently by Sánchez-Hernández and Barco
et al. in 2005, as respectively Galveosaurus herreroi and Galvesaurus
herreroi. Both nomina follow the rules of the ICZN, and are thus
nomenclaturally valid. As they are based on the same holotype, they are
objective synonyms and only the senior synonym, Galveosaurus, is valid
regarding the ICZN.
> The English sauropod Cetiosaurus:
The holotype of its type species, Cetiosaurus brevis, is undiagnostic
according to Upchurch and Martin (2003). Although Cetiosaurus and
Cetiosaurus brevis are valid regarding nomenclature, they are invalid
regarding taxonomy (nomina dubia). Cetiosaurus includes also C.
oxoniensis, which is based on diagnosable material. If the ICZN accepts
to suppress C. brevis as proposed by Upchurch et al. and chooses instead
C. oxoniensis as type specie, then Cetiosaurus would be valid
nomenclaturally AND taxonomically.
> The Nigerien iguanodont Gravisaurus tenerensis:
This nomen was erected in the PhD dissertation of Chabli in 1988, but it
is not published sensu the ICZN. Even if the specimen described
represent indeed a new taxon according to taxonomists, this taxon was
invalid taxonomically until it was given a proper name - Lurdusaurus
tenerensis - in 1999 by Taquet and Russell.
PS: I just had an idea; what do you think of: "approved"/"reprouved" for
taxonomy and "valid"/"invalid" for nomenclature ?