Binomial Nomenclature

We studied about Classification and taxonomic categories in previous topics. In this topic, we are going to discuss binomial nomenclature which deals with how the name is given to each and every organism.

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Nomenclature

Giving a name for different taxa/organism is called nomenclature. It is giving two types of names such as common name and biological name e.g. potato – Solanum tuberosum.

Binomial nomenclature and Trinomial nomenclature are the techniques of Nomenclature.

The living organisms around us are called by the local names which generally differs from one place to another (differs from language to language). So it becomes difficult to identify the plant or animal in general. Hence there is a need to standardize naming the organisms. Scientists have formulated certain procedures to assign the scientific name to each and every organism. International Code of Botanical Nomenclature (ICBN) for plants and International Code of Zoological Nomenclature (ICZN) for animals were evolved to assign scientific names for plants and animals respectively.

What is Binomial Nomenclature?

Binomial nomenclature is the formal system of naming species. Each species is given a two-part name, the first name is genus and it starts with capital letter. The second part name is species or epithet and it should be in the small letter. This was given by Carolus Linnaeus and is used by biologists all over the world. Both names should be in italicized or underlined if handwritten. Example – Mangifera indica (Mango); here Mangifera is the generic name and indica is the specific name.

This system of giving a name to an organism is called binomial nomenclature. In Zoological circles, it is called binary nomenclature and in botanical circles, it is called binomial classification system. Names are given in Latin.

Fig. Carolus Linnaeus

General Rules for nomenclature

The following rules and regulations to be followed while naming the organisms

1. Each and every scientific name of species should be formed by the combination of two words and should be in the Latin language.
2. The first part is genus name and is also called by different technical terms like specific descriptor, specific name (Zoology) and specific epithet (Botany)
3. Species names should be written in italics or underlined e.g., Panthera tigris or Panthera  tigris
4. The genus name should start with capital letter and specific name should be in the small letter. E.g., Homo sapiens (In Zoology). Earlier in botany, specific epithet was written in the capital letter when it was based on the name of a person or place. But it is discontinued so the specific epithet is written usually in lower case e.g., Narcissus papyraceus
5. Author name appears at the end of the scientific name in an abbreviated form. e.g., Homo sapiens Linn. it indicates that the species is first described by Linnaeus.

There are several terms for the two-part name. They are binomen (plural binominal), binomial, binomial name, binominal, binominal name, and species name.

Higher and lower taxa in nomenclature are as follows

1. Above species, all taxa at ranks such as phylum should have a name composed of one word only. “Uninominal name”.
2. The first level subdivisions within a species termed subspecies and it is given a name with three parts. The two parts indicating the species and a third part indicating the subspecific name. (Subspecies within the species). This is known as trinomial nomenclature e.g., Panthera tigris tigris  (Bengal tiger).

Several species or indeterminate species

In general, the scientific name should be several species from the same genus are listed or discussed in the same paper or report then the genus is written in full when it is first used it should be in full form.  After that abbreviated form can be used for successive species names. Canis lupus becomes C.lupus and Escherichia coli is often referred as E.coli when it is referred the second time in a paper. When the specific name cannot or need not be specified then it can be written as ‘sp’ (abbreviated form). “spp” denotes several species and these are not italicized.

Carolus Linnaeus (1707-1778) Swedish botanist and physician attempted to describe the entire known natural world and gave every species (mineral, vegetable or animal) a two-part name. Systema Naturae was published by Linnaeus in 1735. This describes 4400 species of animals and 7700 species of plants. Though Gaspard Bauhin and Johann Bauhin were developed binomial nomenclature, the Linnaeus was the first to use it consistently.

Codes of Nomenclature

The naming the organism became apparent that a body of rules was necessary to govern scientific names. For animals (International Code of Zoological Nomenclature, 1758(ICZN), Plants (including fungi and cyanobacteria) naming body (International Code of Botanical Nomenclature, 1753 (ICBN), for bacteria, 1980 (ICNB) and for Viruses (International Committee on Taxonomy of viruses, ICTV).

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