SPECIAL ISSUE 34a.pdf - Biology International

Biology International, Speciat Issue No. 34 (1 997)
the zoological Code, precedence mns across those ranks that are considered to
be within each of three rank groups, the species group, comprising species and
subspecies (and also superspecies if used), the genus group, comprising genus
and subgenus, and the family group comprising superfamily, family, subfamily,
tribe and subtribe. Any name published in any of these ranks is considered to
have also been published with the same precedence in each of the other ranks of
the particular rank group. This is termed "CO-ordinate status" and Table 3
illustrates the effect that CO-ordinate status has on the choice of correct narne
under some examples from the botanical and zoological Codes. Although the
Bacteriological Code treats subspecies and species as different ranks and, like
the botanical Code, but unlike the zoological, requires forma1 transfer from one
to the other, it resemble the zoological Code in athibuting equal priority at the
two ranks, namely that of the earlier publication. Melville (1986) discusses the
philosophical basis for the zoological rule on CO-ordinate status.
(iii) Secondary Homonymy
Whereas the general principles of precedence based on first publication of new
scientific names is cornmon across al1 codes, biologists have had much more
difficulty in determining precedence when a taxonornic change is made such
that a taxon, most notably a species, is placed in a different genus from that in
which it was originally described. There are three logical alternatives, and al1
have been adopted at different times. Cunently the zoological Code adopts one
of them and the botanical and bacteriological Codes another.
The first possibility is to regard the first binomen used in the new genus as
having precedence regardless of the correct name in any other genus, including
that in which the species was originally published. This was the basis of the so-
called Kew Rule, widely used in botany in the 19th century, e.g. not only at the
RBG, Kew, but by Asa Gray (Harvard) and Adolf Engler (Berlin) (cf. Stevens,
1991), and most noted as being the basis for some of the taxonomic 1
nomenclatural judgements of accepted narnes in Index kewensis (cf. Nicolson,
1991).
The first botanical Code, the Vienna Rules of 1905, established the procedure
that exists today in botany and bacteriology, namely that the earliest epithet is to
be retained on transfer to another genus, unless by doing so a later homonym
would be created because of the previous use of the same epithet with that
generic name based on a different type.
The third alternative, that used in zoology, involves the concept of secondary
homonymy, in that the earliest epithet is to be used regardless of whether there
is already an independent pre-existing use of that epithet in the genus to which
the species is being transferred. In such a case, the transfer creates a secondary
homonym, whose name must therefore be changed.
Table 4 illustrates the differential effects of the three logical alternative
procedures on the nomenclature of two azaleas, species of the deciduous Section
Pentanthera of the genus Rhododendron. Table 5 gives M er examples of the