[Zoobank-list] Taxonomy vs. Nomenclature

[Richard Pyle]

Apologies for the cross-post, but this is an issue that spans both email
list domains.

Izya Kerzhner wrote (in part):

> In addition, some members of the Commission and even of the
> Editorial Committee
> shared the distributed confusion between purposes of taxonomy and
> nomenclature.

This is a topic that I feel needs to be clarified on these lists, because it
seems that confusion between purposes of taxonomy and nomenclature persist.

I think it would be helpful to quote the first three "Principles" of the
ICZN Code, as they appear on p. XIX of the 4th Edition:

===========================
Principles

There are certain underlying principles upon which the Code is based. These
are as follows:

(1) The Code refrains from infringing upon taxonomic judgment, which must
not be made subject to regulation or restraint.

(2) Nomenclature does not determine the inclusiveness or exclusiveness of
any taxon, nor the rank to be accorded to any assemblage of animals, but,
rather, provides the name that is to be used for a taxon whatever taxonomic
limits and rank are given to it.

(3) The device of name-bearing types allows names to be applied to taxa
without infringing upon taxonomic judgment. Every name within the scope of
the Code (except for the names of "collective groups" and of taxa above the
family group) is permanently attached to a name-bearing type. For species
and subspecies this name-bearing type is either a single specimen or a
number of specimens that together constitute the name-bearer; for genera and
subgenera it is a nominal species; for taxa at ranks of the family group it
is a nominal genus. Accordingly, when a taxon at any rank is delineated by a
taxonomist it may contain several name-bearing types, each with a name that
is available for use at that rank. The Principle of Priority (which may be
modified in its operation in the interests of stability and universality -
see (4) below) is used to determine which of those names is the valid one.
============================

When a new animal species name is originally proposed, two abstract
"objects" are established:

#1) A name "object", the availability and relative priority of which are
determined by rules in the ICZN Code, and which has no objective physical
existence other than the fixed association with a single name-bearing
holotype (or set of name-bearing syntypes); and

#2) A taxon concept "object", representing a circumscription of many, many
individual organisms in nature, the scope of which is defined through the
citation of specimens including and often extending beyond the name-bearing
type(s) (e.g., paratypes and other observed or vouchered individual
organisms), and the description of physical (or biochemical, or sometimes
ethological) characteristics purported to collectively identify the
boundaries of the taxon concept (i.e., enabling other taxonomists to
determine whether a given individual organism falls within, or outside of,
the concept circumscription).

Almost everything about the ICZN Code (i.e., the "legalities" of zoological
nomenclature) is focused on defining a name object (#1).  In only a few
cases (e.g., Arts. 13.1.1, 75.3.2) does the Code involve attributes of a
taxon concept (#2). With regard to the *original* taxon concept (i.e., that
which accompanied the establishment of availability of the name), as far as
I can determine, only 13.1.1 has relevance (if anyone knows of other
Articles that involve attributes of a taxon concept object, please indicate
which ones).

On the other hand, the *science* of taxonomy deals primarily with
definitions of taxon concepts. Throughout history, taxonomists have (and
will continue to) re-define the "boundaries" of taxonomic concepts.  These
definitions and re-definitions do not have any direct impact on the
definitions of the name objects.  This point is especially important, and
very prone to misunderstanding.

Yes, of COURSE it is true that when taxon concept definitions change such
that more than one name-bearing type [or series] are included within a new
concept circumscription, then the subjective *status* of name objects
attached to those different [sets of] circumscribed type specimens may
change [i.e., the name object attached to the circumscribed type
specimen/series that has the greatest priority according the Code will be
regarded as a senior synonym, and the name(s) attached to other
circumscribed type(s) will be regarded as junior synonym(s)]. But the
subjective *status* of a name object, according to any particular author(s)
at any particular moment in time, is NOT part of the *definition* of the
name object.

Thus, though taxon concept definitions may expand or contract to include or
exclude name-bearing type specimens, those expansions and contractions have
no impact on the name objects themselves.

One could argue that "prevailing use" clauses in the Code *can* redefine
name objects by changing the relative priority status of each name.  But
this is true only if one considers "priority" a defining attribute of a name
object (I do not). Even still, anyone who has subscribed to the ICZN email
list knows how "unfortunate" the prevailing use clauses have proven to be.

In modern taxonomy, new names are usually established concurrently with a
new taxon concept definition, via a traditional scientific publication.
Certain specific components of the information contained in a published
description (probably less than 10%, on average) constitute the minimum
informational components necessary to establish availability of the name
under ICZN rules (e.g., type designation, etc.)  The rest of the (90%+)
informational content of typical modern species descriptions usually
includes information about the name-bearing type(s) (that serves as a
convenient surrogate to other taxonomists to alleviate the need to examine
the type material themselves), information about other examined material and
morphological character parameters (which define the boundaries of the taxon
concept circumscription), and "speculations" (ahem) about phylogenetic
affinities with other defined taxon concepts. These are the components that
make up the "science" content of taxonomic publications.

My argument about de-coupling procedures of nomenclatural availability from
procedures of defining and re-defining taxon concept definitions is shaped
by the distinction between name objects and taxon concept objects.  Although
many taxonomists are reluctant to acknowledge it, the process of scientific
nomenclature is not science -- any more than the process of assigning ISBN
numbers to published books is equivalent to the intellectual content of
those books.  Nomenclature is a vehicle for information exchange among
researchers engaged in the *science* of taxonomy. And I strongly believe
that the long-term interest of both (nomenclature and taxonomy science) are
best served by disentangling the processes of nomenclatural establishment
and availability, from the science of taxon concept definition and
relationship hypotheses.

I apologize for the length of this message.  I will compensate by exercising
greater restraint in the volume of my posts to these two lists (at least for
the next couple of weeks...)

I would like to close this message with one final quote:

"But it seems likely, in the longer term, and with the development of new
information systems, that the solution will not lie in patching up a
definition of publication but, rather, in scrapping it and finding a means
of replacing 'publication' as a primary determinant of availability."
   - ICZN Code, 4th Edition, p. XXV.

Aloha,
Rich

Richard L. Pyle, PhD
Ichthyology, 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