A Note on ICZN

International Code of Zoological Nomenclature (ICZN)

Nomenclature means allocation of name to the taxa. The term ‘nomenclature’ comes from the Latin words ‘nomen’ (=name) and ‘calore’ (=to call), which literally means “to call by name”. It would be impossible to refer the enormous number of taxa if each one did not have a separate name. Through nomenclature, labels are provided for taxa at all levels to facilitate communication among biologists. The scientific names of taxa at all levels in which they are placed form a system of communication, a language; these names must fulfill the same basic requirements as any other language. So, to have an International scientific language “International Code of Zoological Nomenclature” was framed.

International Code of Zoological Nomenclature:

The set of rules, system and recommendations for zoological nomenclature authorized by the “International Congress of Zoology” is called “International Code for Zoological Nomenclature” (ICZN). This code consists of three main parts – The Code Proper, Appendices, and Glossary. The Code Proper includes “Preamble” followed by 90 consecutively numbered “Articles” grouped in 18 chapters. Each article is composed of one or more mandatory provisions, which are sometime accompanied by “Recommendations”. There are three appendices, the first two have the status of recommendations and third is the constitution of the Commission. The terms used in the text are clearly defined in the “Glossary”,

Origin (History) of the Code:

Linnaeus was the first to mention a sets of rules of nomenclature in his book “Critica Botanica” (1737) and “Philosophica Botanica” (1751). During 19^th century more and more new and lcal 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 11^th Jan/1961. It was approved by the Commission and formally accepted as the “International Code of Zoological Nomenclature” adopted by the “XV International Congress of Zoology”, London, 1958 and published by “International Trust for Zoological Nomenclature”, London 1961. In 1988, the “International Commission on Zoological Nomenclature” set up an Editorial Committee for the preparation of Fourth Edition. The Committee prepared a draft after receiving comments and suggestions from the Zoologists of all over the globe. The draft was accepted by the Commission, 1997 and published in 1999. Recently in 2008, the “International Commission on Zoological Nomenclature” published a proposed amendment to the ICZN and accordingly the article 8.1 is modified to accommodate electronic publication with effect from 1^st January/2012. Amendment of e-publication also introduced to the article 8, 9,10, 21 and 28 with effect from 1^st January/2012.

The objective of the Code:

The objective of the Code was highlighted in the first edition of the International Code of Zoological Nomenclature, 1961. There are three basic objective of the Code –

1. Uniqueness: Every scientific name has to be unique because it is the key to its entire literature relating to this species or higher taxon.

2. Universality: The communication regarding scientific name would be very difficult if we had only vernacular names in different languages; specialists would have to learn the name of taxa in innumerable languages in order to communicate with each other. To avoid this, zoologists have adopted by International agreement to use single language and a single set of names for each animals and its taxonomic groups. So, scientific names for taxa are universally accepted.

3. Stability: If scientific names are frequently changes than the communication would be hampered. So, ICZN emphasized to retain the stability of scientific name by creating “Law of Priority”.

Preamble:

The International Code of Zoological Nomenclature is the system of rules and recommendations originally adopted by the International Congresses of Zoology and, since 1973, by the International Union of Biological Sciences (IUBS).

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.

Priority of publication is a basic principle of zoological nomenclature; however, under conditions prescribed in the Code its application may be modified to conserve a long-accepted name in its accustomed meaning. When stability of nomenclature is threatened in an individual case, the strict application of the Code may under specified conditions be suspended by the International Commission on Zoological Nomenclature.

Precision and consistency in the use of terms are essential to a code of nomenclature. The meanings given to terms used in this Code are those shown in the Glossary. Both this Preamble and the Glossary are integral parts of the Code's provisions.

The International Commission on Zoological Nomenclature is the author of the Code.

Chapters of the ICZN:

The “Preamble” is followed by 18 chapters which includes 90 consecutively numbered “Articles”.

Chapter 1: Zoological nomenclature (Article 1 to 3)

Chapter 2: The number of words in the scientific names of animals (Article 4 to 6)

Chapter 3: Criteria of publication (Article 7 to 9)

Chapter 4: Criteria of availability (Article 10 to 20)

Chapter 5: Date of publication (Article 21 to 22)

Chapter 6: Validity of names and nomenclatural acts (Article 23 to 24)

Chapter 7: Formation and treatment of names (Article 25 to 34)

Chapter 8: Family-group nominal taxa and their names (Article 35 to 41)

Chapter 9: Genus-group nominal taxa and their names (Article 42 to 44)

Chapter 10: Species-group nominal taxa and their names (Article 45 to 49)

Chapter 11: Authorship (Article 50 to 51)

Chapter 12: Homonymy (Article 52 to 60)

Chapter 13: The type concept in nomenclature (Article 61)

Chapter 14: Types in the family group (Article 62 to 65)

Chapter 15: Types in the genus group (Article 66 to 70)

Chapter 16: Types in the species group (Article 71 to 76)

Chapter 17: The International Commission on Zoological Nomenclature (Article 77 to 84)

Chapter 18: Regulations governing this code (Article 85 to 90)

Some Important Rules of Zoological Nomenclature:

Zoological nomenclature is the system of scientific names applied to taxonomic units (taxa; singular: taxon) of extant or extinct animals (Article 1.1). Zoological nomenclature is independent of other systems of nomenclature in that the name of an animal taxon is not to be rejected merely because it is identical with the name of a taxon that is not animal (Article 1.1.1).

Some of the important rules of Zoological Nomenclature are as follows –

1. Uni -, Bi -, Tri -, nomenalism:

The scientific name above the sub-genera is uninominal (Art. 28). The Code stipulates standerised endings for the name of super family (-oidea), family (-idea), sub family (-inae), tribe (-ini) and rarely sub tribe (-ina). The names of species are binominal and those of sub species are trinomnal. For example,

The scientific name above the sub genus is started with capital letter and the species and sub species names are started with small letter. The first (Genus) and the third name (species) formed the binominal and the first, third and fourth (Sub species) formed the trinominal nomenclature. The presence of sub genus does not affect the status of nomenclature. The name of the genus, species and sub species are preferably italicized or underlined.

2. Name change and instability of Nomenclature:

The species are frequently are shifted from one genus to the other. Zoological Code has got provisions to govern such changes. Specific name can not be changed if it is valid, but the generic name can be changed. For example, Rohu fish was first discovered by Hamilton in the river Ganges.

Cyprinus rohita Hamilton,1982

Later on the genus name has been changed and the original author’s name is written in the parenthesis.

Labeo rohita (Hamilton), 1822

3. Use of punctuation marks:

Comma is always used in between the author name and the year.

4. Law of Priority:

The name of a taxon is valid if the oldest name of a taxon is ‘valid’ if it is the oldest available name applied to it (Article 23). The date of publication of a name thus is of crucial importance. In zoologucal nomenclature the priciple of priority applies only to the categorial levels of species (and sub species), genus, and family. It does not apply to the higher categories. The ‘Law of Priority’ is thus promot stability to the scientific name. It is restricted to the species (and sub species), genus and family.

5. Starting point date: (Article 3)

The starting point date for zoological nomenclature is 1^st January, 1758, and the 10^th edition of Linnaeus, “Systemma naturae” has been regarded to have been publishedon that date. Any work before 1758 is treated to have been published after that date, except spider nomenclature is considered to have started in 1757 (Clerk, C. 1757, Aranei svecici, Bul, Zoo. Nomenclature 4:319).

6. Formation of name:

Zoological names are written either in Latin or Latinized form, so it is important for the Zoologist to be familiar with the rules that govern the correct transliteration and Latinization of words. The appendices (B,C,D) to the Code are specially devoted to these matters.

7. Use of suffixes ‘i’, ‘orum’, ‘ae’ and ‘arum’ (Article 31.1.2):

These suffixes are used for species group names from modern personal names.

smithi from Smith (Personal name of a man)

smithorum from Smith (if name of men, or man and woman together)

guptae from Gupta (Name of a woman)

smitharum from Smith (Name of women)

8. Use of Suffix ‘ensis’ or ‘iensis’ in taxonomic works:

These are important suffixes used for species group names based on a geographical name, e.g., ludhianensis from Ludhiana, siciliensis from Sicily.

9. Kinds of name (Article 8 to 12):

The zoological name which satisfies the Code is called “available name” or ‘valid” name and which does not satisfy the Code is called “nomen nudum”. A name which replaces the earlier name is called “nomen novum”. Some other important kinds of names are –

Nomen hybridum: - Hybrids are individuals. So, the names of hybrids have no status in nomenclature.

Vernacular name: The name of ataxon in any language other than the language of zoological nomenclature is called vernacular name.

Species inquirenda: A doubtfully identified species needing further investigation is called species inquirenda.

10. Tautonyms (Article 18):

The tautonym is a name of species or sub species in which the second or even the third components of the name repeats the generic name, e. g., Apus apus apus.

11. Synonymy (Article 10 – 11):

Two or more names belonging to the same taxon is called synonyms. Senior synonym got validity according to the “Law of Priority”

12. Homonymy (Article 52 – 60):

Same name to the taxa is called homonymy. Here also senior homonym got validity according to the “Law of Priority”.

13. Typifications (Zoological Type):

The designation of a nomenclatural type is called typification. The Zoological Code recognizes only a few terms like –

Type specimen – the specimen which was selected by the observer.

Holotype – single specimen selected from the collection of observer.

Paratype – other specimen of the observer excluding holotype.

Syntype – more than one specimen selected by the observer.

Lectotype – the single specimen selected by the revisor from the syntype is called lectotype.

Neotype – If the type specimen is lost under certain condition than the revisor can select another specimen and it is called neotype.

14. Power of the Commission:

Article 77 to 84 is devoted to the Power of the Commission. The “International Commission on Zoological Nomenclature” which derives all its power from the “International Congress of Zoology”. The opinions of the Commission are published in the “Bulletin of the Zoological Nomenclature”. The Commission consists of a President, Vice President, Secretary, Assistant Secretary and 25 members from 19 countries. The Commission meets triennially with General Assemblies of “International Union of Biological Science”.

Binominal Nomenclature

Nomenclature (Nomen – name; Calore – to call) means allocation of names to the taxa. Naming of animal is the first and foremost task of every taxonomist. The scientific name of animal should be unambiguous, unique, universal and stable and it is the key to its literature. Proper naming of an animal is thus the fundamental principle of nomenclature. The vernacular names exist in all languages. So, the same kind of organism is called by different names in different places. On the otherhand same name is used to different organisms in the single language. So, to avoid such defects, the taxonomists universally accept some sets o0f rules called “Code of Nomenclature”, which is fixed by “International Congress of Zoology”.

Carolus Linnaeus is called father of the “Taxonomists” was the first to introduce binominal nomenclature, in which every animal and plant is given two names, a specific name, which particularizes the species from others and ageneric name which is placed before the specific name. Binominal nomenclature of Linnaeus has become widely accepted in the modern system of classification. Linnaeus (1758) in his 10^th edition of the book “Systemma Naturae” listed 4,236 different scientific names for animals.

Rules of binominal nomenclature:

In biology, binominal nomenclature is the formal system of naming specific species. In the “International Code of Zoological Nomenclature” there are some rules for binominal nomenclature. Some of the important rules are mentioned below.

1. The specific name of an organism has two parts, - ie. the first part is the name of the genus and the second part is the name of species.

Eg – Labeo rohita

Here the Labeo is the generic name and the rohita is the specific name.

2. No names are recognized prior to those included by Linnaeus in his “Systemma Naturae”, 10^th edition, 1^st January, 1758.

3. Genus name should be single name and started with a capital letter.

4. The species name begins with a small letter.

5. The scientific names are always written in Latin or in Latinized form and printed in Italics form. In hand writing the names are underlined separately.

6. The name or the initial of the name of the author of a valid scientific name should be mentioned in the ending of the scientific name.

Eg, Canis familiaris L

Here, L is used for Linnaeus and he is the author of the above mentioned scientific name. The author name or the initial is not apart of scientific name, so its mention is also not compulsory.

7. Comma is always used in between the author’s name and the year of publishing, for example,

Labeo rohita Hamilton, 1822

8. When a scientific name is changed than the generic name is changed but thespecific name remain constant or same. So, the specific name frequently shifted from one genus to another. For example, the ‘bee’ species jenseni was earlier published under the genus Nomia, but presently belongs to the genus Leiproctus.

9. The author’s name is put in parenthesis when the species is transferred from one genus to the other retaining its original author and date. It is called new combination, for example, Hemilea bipars (Walker, 1862) Hardy, 1959. This means Walker described the bipars originally in some other genus but Hardy in 1959 treansferred itto the correct genus Hemilea.

10. When different names are proposed by different authors than according to the “Law of Priority” the first name get validity.

11. The numerical of the scientific name are to mbe written in word as numerical adjective.

Eg, decimlineata – correct

10 – liniata – incorrect

12. In case of scientific names the second or even the third part (Sub species) can repeat the first name

Recommendations for binominal nomenclature:

1. A name should be in Latin or easily converted into Latinized form.

2. A name should not contain less than three or more than twelve letters.

3. A name should be easy to pronounce.

4. The name given should preferably have some characteristics of the organism.

5. A name should not be derived from two languages.

6. A name should not be frivolous.

Advantage binominal nomenclature:

Although at present many scientists suspect about the utility of binominal nomenclature, yet this system is used widely in modern classification. The validity of classification and identification is depending upon the basis of binominal nomenclature. The main advantages of binominal nomenclature are –

1. It provides stability, uniqueness, and universality to the scientific names.

2. All hitherto known organisms irrespective of their utility have been provided with scientific names. It helps in classification.

3. A newly discovered organism can be described and named.

4. The scientific names indicate relationship of a species with the others present in the same genus.

5. The scientific names are derived from Latin or Greek words and both of these are dead language, hence there is less possibility of change of the meaning of their words.

6. They are comprehensive and easier to recollect.

7. The scientific names are often descriptive, indicating some important characteristics of the organism.

8. A wrong name can easily be corrected.

Disadvantage binominal nomenclature:

1. There were only 312 genus at the Linnaean time and the task of remembrance is not a difficult problem for these limited genus. Now a days the number of genus increases up to more than 50,000. These extreme generic splitting and shifting of species groups leads to the instability of nomenclature system.

2. The word species has no meaning independently. As for example the generic name of horse is Equus. The genus Equus has two species ie, E. caballus and E. asinus. Individually specific word caballus and asinus are meaningless.

3. Linnaeus taxonomy does not formally incorporate phylogeny. Linnaean hierarchical system based largely based on similarities in their forms and other traits but not always reflect evolutionary relationship.

Although at present many scientists suspect about the utility of binominal nomenclature, yet this system is used widely in modern classification. The validity of classification and identification is depending upon the basis of binominal nomenclature.

Trinomial nomenclature:

The trinomial nomenclature system is employed to name the sub species. In zoological classification the subspecies is a category below the species. A trinomen is a name consisting of three names: generic name, specific name and sub specific name.

· All three names are typeset in italics, and only the generic name is capitalized.

· The sub species name is also a Latin or Latinized word.

· If the generic and specific name is mentioned in the same paragraph, they are often abbreviated to initial letters, for example the trinomial name of Phalacrocorax carbo novaehollandiae (Great cormorant of Australasia) might be writen as P.c. novaehollandiae.

The shortest trinomial tautonym is the Bufo bufo bufo (European toad) and Naja naja naja (Shri Lankan cobra). The longest trinomial tautonym is Coccothraustes coccothraustes coccothraustes (Hawfinch).