INTERNATIONAL CODE OF ZOOLOGICAL NOMENCLATURE

Overview of ICZN - Origin, Principles, Rules, Significance.

1. INTERNATIONAL CODE OF
ZOOLOGICAL NOMENCLATURE
BY
MAHATHUM NASEERA M
1st M.Sc - ZOOLOGY

2. WHAT IS ICZN?
The International Code of Zoological Nomenclature
(ICZN) is a widely accepted convention in zoology that
rules the formal scientific names of organisms treated as
animals.
The International Code of Zoological Nomenclature
consists of a pack of rules and recommendations that
govern the scientific names of animals.
These rules and recommendations are designed to
promote stability and order in animal taxonomy and
to ensure that each animal's name is unique.

3. Nomenclature comes from a Latin word meaning "the assigning of names."
The system of providing organisms with appropriate and distinct names is called nomenclature.
The principles of naming vary from the relatively informal convection of everyday speech to the
internationally agreed principles, rules and recommendations that govern the formation and use
of the special terms used in scientific and any other disciplines.
The Linnaean system of binomial nomenclature was established in the 1750s by Carlos .
What is nomenclature ?

4. THE CONTENTS OF ICZN
ORIGIN OF
ICZN
PRINCIPLES
RULES
PARTS

5. Linnaeus was the first to mention a sets of rules of nomenclature in his
book “Critica Botanica” (1737) and “Philosophica Botanica” (1751).
During 19th century more and more new sets of rules originated in
different countries.
So, to have an International Code, Professor Blancherd prepared a sets of rules, which
were presented at the 1st “International Congress of Zoology” held in 1889 in Paris,
but accepted only in the 2nd “International Congress of Zoology”, Moscow, 1892.
Later after a revision a final draft was prepared and circulated to the “International
Commission of Zoological Nomenclature”, on 11th January 1961.
It was approved by the Commission and formally accepted as the “International
Code of Zoological Nomenclature” and published by “International Trust for
Zoological Nomenclature”, London 1961.
ORIGIN OF ICZN:

6. PRINCIPLES
According to this principle, the scientific name of a species is a combination of two
names. The name of the species is composed of Generic name and Specific name.
2. PRINCIPLE OF PRIORITY:
PRINCIPLE OF BINOMIAL
NOMENCLATURE:
1.
According to this principle the correct formed scientific name of a species is the
first or oldest available valid name.
The oldest published name is considered to be the valid name of the taxon, provided
that the name is not invalidated by any provision of code or by any ruling of the
commission.
This Principle of Priority is applied only to the names published after 01.01.1758.
The Principle of Priority also provides that every name must have its authorship,
since priority doesn't apply to anonymously published names.

7. Citation indicates who published the name; in what publication; with the
In taxonomy, it is generally conventional for the species to have the
In citing the name of an author, the surname is given in full;not
Date (year) of publication is also added, if desired with a comma
Author's name without parenthesis means that the species
AUTHORSHIP:
date of the publication.
name of person as a suffix (who first described the species).
abbreviated.
between author and date (the comma is not prescribed under the code).
Eg: Balaena mysticetus Linneaus,1758 (Bowhead whale) described by
Linneaus.
remains in the genus originally used by the author who described it for
the first time.

8. The use of paranthesis is required when the species is transferred from one
genus to the other.
It is retaining its original author and date.
It is also called New combination.
The use of square bracket denotes the original anonymity.
It is used to include the statement of misidentification.
3. USE OF PARANTHESIS:
Eg: Hemilea Bipars (Walker) Hardy 1959.
4. USE OF SQUARE BRACKET:

9. According to this principle, when a new name is established for a taxa, it
automatically establishes all corresponding names in relevant ranks.
5. PRINCIPLE OF COORDINATION:
Eg: Giraffa camelopardalis Linneaus,1758 also establishes subspecies. The same
applies to the name of a subspecies, this establishes the corresponding species
name.
6. USE OF SUFFIXES:
If the species names are framed after any person’s name, the endings of the species
are i, ii and ae, or if the species name are framed after geographical place, the
endings of the species are ‘ensis’ & ‘iensis’.

10. Eg:

11. A tautonym is a scientific name of a species in which both parts of the name
have the same spelling, such as Rattus rattus.
It is a binomial name in which the genus and the species are given the same
name.
Synonyms are the different names for a same animal or a taxon (species or
genus).
If the several scientific names are given to a single animal by different
scientists, the senior-most name is selected by law of priority.
6. TAUTONYMS:
Eg: The species of gorilla whose scientific name is Gorilla gorilla & Iguana
iguana is another example of a tautonym.
7. SYNONYMS:

12. The senior-most or earliest name is called senior synonym and is considered
as valid species and the rest of the names are called junior synonyms and are
treated as invalid species.
The leopard cat was named Felis bengalensis by Kerr and the same animal was
named by Gray, Felis chinensis. Again this animal was named as Prionailurus
bengalensis by Kerr. So the first name is Senior synonym and valid and the
rest names are junior synonyms and are invalid.
The selection of the proper name applicable to the taxon is done through " Law
of Priority"
2 TYPES OF SYNONYMS -
1. Subjective synonyms: The synonymy is open to taxonomic judgement.

2. Objective synonyms: It refers to taxa with the same type and same rank.

13. Homonyms applies when identical names are given to two or more different
taxa.
According to the zoological code when two or more homonyms are found,
the seniormost (oldest) homonym is used and the junior most homonyms
are replaced with new names.
8. HOMONYMY:
Eg: Cuvier proposed the genus Echidna in 1797 for the spiny anteater.
Forster had already published the name Echidna in 1777 for a genus of
moray eels.

14. RULES OF ICZN
When we are writing the scientific names it is necessary to follow certain
International rules which are:
1. The scientific name (Genus name, Species name and Subspecies
name) should be written or printed in Italics.
2. The genus name or generic name must start with the capital letter.
3. The species name or the specific name must start with the small
letter.
4. The generic name should be followed by the specific name.

15. 5. In case different scientists have named the same genus or species differently,
the names which are published first are accepted.
6. A family name is formed by suffix-IDEA to the name of the genus and the
name of the sub family is formed by suffix-INAE.
PARTS OF ICZN:
(i) The Code proper,
(ii) The Appendices and
(iii) The Official glossary.
- The code proper includes a preamble followed by 90 articles which cover
mandatory rules without any explanation.
- There are three Appendices, of which the first two cover the status of
recommendations and the third part of the Appendices is the constitution

16. The objects of the Code are to promote stability and universality in the
scientific names of animals and to ensure that the name of each taxon is
unique and distinct.
All its provisions and recommendations are subservient to those ends and
none restricts the freedom of taxonomic thought or actions.
The Commission currently comprises 26 members from 20 countries.
The work of the Commission is supported by a small Secretariat based at the
Lee Kong Chian Natural History Museum in Singapore.
of the commission.
- The glossary contains the terms used in the codes with detailed definition.
SIGNIFICANCE:

17. ICZN publishes the International Code Of Zoological Nomenclature
containing the rules which are universally accepted as governing the
application of scientific names to all organisms which are treated as
animals.
ICZN provides rulings on individual nomenclatural problems & brought to
its attention, in order to achieve internationally acceptable solutions and
stability.
These rulings are published as 'Opinions' in the Bulletin of Zoological
nomenclature.
The Commission operates in two main ways:

18. THANK YOU
ENSURE A UNIQUE SCIENTIFIC NAME FOR EACH TAXON