[Taxacom] Diagnoses of higher monotypic taxa

[Paul van Rijckevorsel]

From: "Ohl, Michael" <Michael.Ohl at mfn-berlin.de>
To: <taxacom at mailman.nhm.ku.edu>

> [...] Such cases of a single species nested in a hierarchy of different
> higher (redundant) taxa is often applied to fossil insects, many of which
> are assumed to be in a quite isolated position. However, this problem
> exists in all kinds of organisms.

> [...] So since alle these taxa are actually redundant, that is, based 
> on a single biological unit,

***
This is not quite accurate. A taxon is defined as a taxonomic group/unit
(i.e. what a taxonomist regards as being a group worth distinguishing);
hopefully this taxonomic unit is also a biological unit, but this is in the
eye of the beholder. So in this case there is a single taxon which has
names at various ranks. These names do not have a fixed relationship
with this taxon; later, taxa can be added so as to create differently
circumscribed taxa at each rank. Or, alternatively, recognition can
be withdrawn. After being created, each name (at each rank) will
start to accumulate its own taxonomic and nomenclatural history.

It is axiomatic that the rank of species is basic. In botany it is not
really possible to now publish a name for a new taxon at the rank
of genus or above unless there is a species (first or simultaneously).
And obviously there can be no subdivision of a genus unless there
is a genus (first or simultaneously).

However, in and of itself, it is quite possible to have different
descriptions or diagnoses for the same taxon at different ranks.
To some extent this is even prescribed, in that if you want to
fulfil the requirement for a description or diagnosis by referring 
to an existing one this must be an appropriate one (i.e. you 
cannot publish a new name at the rank of family by referring
to a description or diagnosis of a species, but this must be 
one of a family, or a subdivision of a family).

Paul