In scientific nomenclature, a synonym is a scientific name that
applies to a taxon that (now) goes by a different scientific name,
although the term is used somewhat differently in the zoological code
of nomenclature. For example, Linnaeus was the first to give a
scientific name (under the currently used system of scientific
nomenclature) to the Norway spruce, which he called Pinus abies. This
name is no longer in use: it is now a synonym of the current
scientific name which is Picea abies.
Unlike synonyms in other contexts, in taxonomy a synonym is not
interchangeable with the name of which it is a synonym. In taxonomy,
synonyms are not equals, but have a different status. For any taxon
with a particular circumscription, position, and rank, only one
scientific name is considered to be the correct one at any given time
(this correct name is to be determined by applying the relevant code
of nomenclature). A synonym cannot exist in isolation: it is always an
alternative to a different scientific name. Given that the correct
name of a taxon depends on the taxonomic viewpoint used (resulting in
a particular circumscription, position and rank) a name that is one
taxonomist's synonym may be another taxonomist's correct name (and
Synonyms may arise whenever the same taxon is described and named more
than once, independently. They may also arise when existing taxa are
changed, as when two taxa are joined to become one, a species is moved
to a different genus, a variety is moved to a different species, etc.
Synonyms also come about when the codes of nomenclature change, so
that older names are no longer acceptable; for example, Erica herbacea
L.. has been rejected in favour of
1 General usage
4 Comparison between zoology and botany
General usage To the general user of scientific names, in fields such as agriculture, horticulture, ecology, general science, etc., a synonym is a name that was previously used as the correct scientific name (in handbooks and similar sources) but which has been displaced by another scientific name, which is now regarded as correct. Thus Oxford Dictionaries Online defines the term as "a taxonomic name which has the same application as another, especially one which has been superseded and is no longer valid." In handbooks and general texts, it is useful to have synonyms mentioned as such after the current scientific name, so as to avoid confusion. For example, if the much advertised name change should go through and the scientific name of the fruit fly were changed to Sophophora melanogaster, it would be very helpful if any mention of this name was accompanied by "(syn. Drosophila melanogaster)". Synonyms used in this way may not always meet the strict definitions of the term "synonym" in the formal rules of nomenclature which govern scientific names (see below). Changes of scientific name have two causes: they may be taxonomic or nomenclatural. A name change may be caused by changes in the circumscription, position or rank of a taxon, representing a change in taxonomic, scientific insight (as would be the case for the fruit fly, mentioned above). A name change may be due to purely nomenclatural reasons, that is, based on the rules of nomenclature; as for example when an older name is (re)discovered which has priority over the current name. Speaking in general, name changes for nomenclatural reasons have become less frequent over time as the rules of nomenclature allow for names to be conserved, so as to promote stability of scientific names. Zoology  Further information: Valid name (zoology)
The Latin Caudata and Greek Urodela both mean "tailed" and have been used as a scientific name at the taxonomic rank of order for the salamanders (as opposed to the tail-less frogs). Thus they are synonyms.
In zoological nomenclature, codified in the International Code of
The hierarchy of biological classification's eight major taxonomic ranks. Intermediate minor rankings are not shown.
a particular species could have two or more species-rank names published for it, while a particular order could have two or more order-rank names published for it as well.
The earliest published name is called the senior synonym, while the
later name is the junior synonym.
One basic principle of zoological nomenclature is that the earliest
correctly published (and thus available) name, the senior synonym, by
default takes precedence in naming rights and therefore, unless other
restrictions interfere, must be used for the taxon. However, junior
synonyms are still important to document, because if the earliest name
cannot be used (for example, because the same spelling had previously
been used for a name established for another taxon), then the next
available junior synonym must be used for the taxon.
Objective synonyms refer to taxa with the same type and same rank
(more or less the same taxon, although circumscription may vary, even
widely). This may be species-group taxa of the same rank with the same
type specimen, genus-group taxa of the same rank with the same type
species or if their type species are themselves objective synonyms, of
family-group taxa with the same type genus, etc.
In the case of subjective synonyms, there is no such shared type, so
the synonymy is open to taxonomic judgement, meaning that there is
room for debate: one researcher might consider the two (or more) types
to refer to one and the same taxon, another might consider them to
belong to different taxa. For example,
John Edward Gray
Homotypic, or nomenclatural, synonyms (sometimes indicated by ≡)
have the same type (specimen) and the same taxonomic rank. The
Linnaean name Pinus abies L. has the same type as
In botany, although a synonym must be a formally accepted scientific name (a validly published name): a listing of "synonyms", a "synonymy", often contains designations that for some reason did not make it as a formal name, such as manuscript names, or even misidentifications (although it is now the usual practice to list misidentifications separately). Comparison between zoology and botany Although the basic principles are fairly similar, the treatment of synonyms in botanical nomenclature differs in detail and terminology from zoological nomenclature, where the correct name is included among synonyms, although as first among equals it is the "senior synonym":
Synonyms in botany are comparable to "junior synonyms" in zoology. The homotypic or nomenclatural synonyms in botany are comparable to "objective synonyms" in zoology. The heterotypic or taxonomic synonyms in botany are comparable to "subjective synonyms" in zoology.
When Dandy described Galium tricornutum, he cited G. tricorne Stokes
(1787) pro parte as a synonym, but explicitly excluded the type
(specimen) of G. tricorne from the new species G. tricornutum. Thus G.
tricorne was subdivided.
The Angiosperm Phylogeny Group's summary of plant classification
states that family
Chresonym Glossary of scientific naming Ornithocheirus – a case history
^ ICN, "Glossary", entry for "synonym" ^ ICZN, "Glossary", entry for "synonym" ^ ICN, Appendix IV ^ Definition of synonym from Oxford Dictionaries Online, retrieved 2011-11-28 ^ ICZN, Art. 61.3 ^ ICZN, Art. 61.3.1 ^ ICZN, Art. 61.3.3 ^ p. 43 in Beck, H. 1837. Index molluscorum præsentis ævi musei principis augustissimi Christiani Frederici. – pp. 1–100 , 101–124 . Hafniæ. ^ ICZN, Art. 23.9 "reversal of precedence" ^ Falkner, G., Ripken, T. E. J. & Falkner, M. 2002. Mollusques continentaux de France. Liste de référence annotée et bibliographie. – pp. [1–2], 1–350, [1–3]. Paris. ^ ICN, Recommendation 50D ^ Matthews, S. C. (1973), "Notes on open nomenclature and synonymy lists" (PDF), Palaeontology, 16: 713–719. ^ Berendsohn, W. G. (1995), "The concept of "potential taxa" in databases" (PDF), Taxon, 44 (2): 207–212, doi:10.2307/1222443, JSTOR 1222443.
Blackwelder, R.A. (1967), Taxonomy: A text and reference book, New
York: Wiley, ISBN 978-0-471-07800-5
Dubois, A. (2000), "Synonymies and related lists in zoology: general
proposals, with examples in herpetology", Dumerilia, 4 (2):
International Commission on