[Taxacom] Why stability? - Revisited

[Richard Pyle]

The type specimens have one real functional role: to help decide which Linnean taxon name to apply to a concept.

When taxonomists define species-level taxon concepts, one of three possible circumstances may exist:

1) The concept circumscription does not include any individual organisms that have been designated as a name-bearing type for an available/validly-published Linnean name;

2) The concept circumscription includes exactly one organism that has been designated as a name-bearing type for an available/validly-published Linnean name;

3) The concept circumscription includes more than one organism that has been designated as a name-bearing type for an available/validly-published Linnean name.

In the first circumstance, a taxonomist is prompted to select one individual from within the taxon concept circumscription to serve as the name-bearing type for a new Linnean name.

In the second circumstance, the epithet associated with the single name-bearing type is the one that should be used to label the concept (which, among several possibly homotypic name combinations to apply is a question of classification, no nomenclature).

In the third circumstance, a taxonomist must consult the Codes of nomenclature (and associated materials, such as official lists and indexes of works and names) to determine which, among the multiple heterotypic names has the highest nomenclatural priority, and this the name that should be applied to label the concept. These same Codes are used to determine which names are available/validly-published, and which are not.

The principle extends to higher-rank names as well, but I hope that extension is reasonably evident based on a working knowledge of the Codes.

Aloha,
Rich


Richard L. Pyle, PhD
Database Coordinator for Natural Sciences | Associate Zoologist in Ichthyology | Dive Safety Officer
Department of Natural Sciences, Bishop Museum, 1525 Bernice St., Honolulu, HI 96817
Ph: (808)848-4115, Fax: (808)847-8252 email: deepreef at bishopmuseum.org
http://hbs.bishopmuseum.org/staff/pylerichard.html



> -----Original Message-----
> From: Taxacom [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of
> Jim Croft
> Sent: Monday, May 04, 2015 10:36 AM
> To: Weakley, Alan
> Cc: TAXACOM
> Subject: Re: [Taxacom] Why stability? - Revisited
> 
> This is not strictly true. The purpose of the type is to anchor the name, as Paul
> describes. It is not to centre, circumscribe or in any way define the taxon. That
> is a separate process that may end up including one or more types, and hence
> one or more names. At least with plants. People may think they are defining a
> taxon by selecting the 'best' possible type to represent their concept, and it is
> probably a wise thing to do, but this is not what is happening according to the
> Code. They are simply anchoring the name.
> 
> Jim
>  On 05/05/2015 5:20 AM, "Weakley, Alan" <weakley at bio.unc.edu> wrote:
> 
> > The type is a flag in space around which the circumscription of a
> > taxon (its concept) is defined -- usually in relation to other, "competing" taxa.
> >
> > -----Original Message-----
> > From: Taxacom [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf
> Of
> > Paul van Rijckevorsel
> > Sent: Monday, May 04, 2015 7:57 AM
> > To: TAXACOM
> > Subject: Re: [Taxacom] Why stability? - Revisited
> >
> > I was a little uneasy why Stephen Thorpe's attitude that taxa are
> > defined by types is so alien to me.
> >
> > But it is very straightforward: from the very first the 'botanical'
> > Code has laid down that nomenclatural types are not necessarily the
> > most typical or representative element of a taxon (that is, holding
> > only the type, it is not possible to predict with any degree of
> > confidence what the taxon exactly looks
> > like: the type is only the type) .
> >
> > For plants there does exist a situation where the whole unit is
> > determined by a reference specimen, namely in the ICNCP
> > (Cultivated-plant-Code), resulting in names of the type Hydrangea
> macrophylla 'La France'.
> >
> > The ICNCP deals with a field of considerable complexity (and which
> > does benefit from regulation), but taxonomy is not involved.
> >
> > Paul
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