The word taxonomy is derived from two Greek words, ‘taxis’ means arrangement and ‘nomia’ means method. Thus, the taxonomy can be simply defined as the science of classifying biological organisms. Fish taxonomy is concerned with the identification and classification of fishes to the level of species or subspecies, following the conventional principles of basic taxonomy.
The Swedish Botanist Carolus Linnaeus (1707-1778) is regarded as the father of modern taxonomy, as he developed a system known as Linnaean classification for categorization of organisms and binomial nomenclature for naming organisms. However, the word taxonomy was first coined by a French Professor A. P. de Candolle as ‘Taxonomie’ in 1813. Taxonomy has three stages; (i) alpha taxonomy, which deals with the description of new species and its arrangement in comprehensive genera, (ii) beta taxonomy, which works out the relationships to the level of species, and (iii) gamma taxonomy, which emphasis intraspecific variations and their evolutionary relationships. The term ‘taxon’ (plural taxa) refers to the taxonomic group of any rank which is sufficiently distinct to be worthy of being assigned to a definite category.
2.1. Nomenclature of fishes
Nomenclature is the scientific naming of fish or any organisms. Common names frequently vary so they are not reliable for identification. Every living organism has only one unique and internationally recognized scientific name. For example, common carp is called zoologically Cyprinus carpio all over the world. The nomenclature of zoological species is regulated by the International Code of Zoological Nomenclature (ICZN).
Whenever a species or genus is newly described, certain rules of zoological nomenclature have to be taken into consideration. In binomial nomenclature, the name of a species consists of two words, the first word denoting the genus and the second word denoting the species (e.g., Cyprinus carpio). Sometimes a species also has a subspecies, in which the full scientific name becomes trinomial. In case of trinomial nomenclature, the name of a species consists of three words, the first word denoting the genus, the second word denoting the species and the third word denoting the subspecies (e.g., Cyprinus carpio specularis). The genus name is always a noun and written with an initial capital letter while species and subspecies name are generally an adjective and are always written in small letters. The genus, species and subspecies name should be either underlined separately or written in Italic font. When a subgenous name is used, it is placed within parentheses between the geneus and species names [e.g., Channa (Ophiocephalus) striatus]. To indicate many species within a genus, the abbreviation ‘spp.’ is sometimes used and should not be italicized.
In taxonomic classification of fishes, the name of the order generally ends with ‘formes’, of the family with ‘idae’, of the subfamily with ‘inae’ of the tribe with ‘ini’. When the species is described for the first time, its name should be written, for example, as Neoanguilla nepalensis sp. nov., while a new genus should be expressed, for example, as Neoanguilla gen. nov. When the said species is cited by another author, it should be written as Neoanguilla nepalensis (Shrestha) to indicate the author of the species.
2.2. Classification and identification of fishes of Nepal
Fishes have been classified in different ways from time to time. The earliest classification was proposed by J. Muller (1844) who proposed seven sub-classes under the class ‘Pisces’. Later, Berg (1940) and Romer (1959) have given detailed classification of fishes, which have generally been accepted worldwide. In this book, we follow the classification given by Berg (1940), who divided the Super-class (Series) Pisces into seven classes: (1) Acanthodii, (2) Coccostei, (3) Pterichthys, (4) Elasmobranchii, (5) Holocephali, (6) Dipnoi, and (7) Teleostomi (Figure 2.1). Of these, the first three classes are completely extinct and are collectively known as Placodermi (meaning plate-skinned). Thus, the modern fishes are represented only by four major classes, i.e., Elasmobranchii, Holocephali, Dipnoi and Teleostomi. Out of these, the fishes of Nepal belong to the sub-class Actinopterygii of the class Teleostomi. Berg has divided the sub-class Actinopterygii into a series of 59 orders. Out of these, only 11 orders are represented in freshwater ecosystem of Nepal.
The total number of fish species represented in Nepal has been controvercial and is a subject of study. Different fish biologists have reported different number of fish species present in Nepal, which ranged from 228-232. According to Shrestha (2008), a total of 232 species belonging to 114 genera under 36 families and 11 orders existing in culture or natural water bodies of Nepal. Recently, Shrestha and Pandit (2012) have described one more exotic species, Pangasius hypophthalmus (Sauvage), which has been commercially cultured in the terai region of Nepal since few years. This indicated that the total number of fish species present in Nepal might be more than 232.
The Swedish Botanist Carolus Linnaeus (1707-1778) is regarded as the father of modern taxonomy, as he developed a system known as Linnaean classification for categorization of organisms and binomial nomenclature for naming organisms. However, the word taxonomy was first coined by a French Professor A. P. de Candolle as ‘Taxonomie’ in 1813. Taxonomy has three stages; (i) alpha taxonomy, which deals with the description of new species and its arrangement in comprehensive genera, (ii) beta taxonomy, which works out the relationships to the level of species, and (iii) gamma taxonomy, which emphasis intraspecific variations and their evolutionary relationships. The term ‘taxon’ (plural taxa) refers to the taxonomic group of any rank which is sufficiently distinct to be worthy of being assigned to a definite category.
2.1. Nomenclature of fishes
Nomenclature is the scientific naming of fish or any organisms. Common names frequently vary so they are not reliable for identification. Every living organism has only one unique and internationally recognized scientific name. For example, common carp is called zoologically Cyprinus carpio all over the world. The nomenclature of zoological species is regulated by the International Code of Zoological Nomenclature (ICZN).
Whenever a species or genus is newly described, certain rules of zoological nomenclature have to be taken into consideration. In binomial nomenclature, the name of a species consists of two words, the first word denoting the genus and the second word denoting the species (e.g., Cyprinus carpio). Sometimes a species also has a subspecies, in which the full scientific name becomes trinomial. In case of trinomial nomenclature, the name of a species consists of three words, the first word denoting the genus, the second word denoting the species and the third word denoting the subspecies (e.g., Cyprinus carpio specularis). The genus name is always a noun and written with an initial capital letter while species and subspecies name are generally an adjective and are always written in small letters. The genus, species and subspecies name should be either underlined separately or written in Italic font. When a subgenous name is used, it is placed within parentheses between the geneus and species names [e.g., Channa (Ophiocephalus) striatus]. To indicate many species within a genus, the abbreviation ‘spp.’ is sometimes used and should not be italicized.
In taxonomic classification of fishes, the name of the order generally ends with ‘formes’, of the family with ‘idae’, of the subfamily with ‘inae’ of the tribe with ‘ini’. When the species is described for the first time, its name should be written, for example, as Neoanguilla nepalensis sp. nov., while a new genus should be expressed, for example, as Neoanguilla gen. nov. When the said species is cited by another author, it should be written as Neoanguilla nepalensis (Shrestha) to indicate the author of the species.
2.2. Classification and identification of fishes of Nepal
Fishes have been classified in different ways from time to time. The earliest classification was proposed by J. Muller (1844) who proposed seven sub-classes under the class ‘Pisces’. Later, Berg (1940) and Romer (1959) have given detailed classification of fishes, which have generally been accepted worldwide. In this book, we follow the classification given by Berg (1940), who divided the Super-class (Series) Pisces into seven classes: (1) Acanthodii, (2) Coccostei, (3) Pterichthys, (4) Elasmobranchii, (5) Holocephali, (6) Dipnoi, and (7) Teleostomi (Figure 2.1). Of these, the first three classes are completely extinct and are collectively known as Placodermi (meaning plate-skinned). Thus, the modern fishes are represented only by four major classes, i.e., Elasmobranchii, Holocephali, Dipnoi and Teleostomi. Out of these, the fishes of Nepal belong to the sub-class Actinopterygii of the class Teleostomi. Berg has divided the sub-class Actinopterygii into a series of 59 orders. Out of these, only 11 orders are represented in freshwater ecosystem of Nepal.
The total number of fish species represented in Nepal has been controvercial and is a subject of study. Different fish biologists have reported different number of fish species present in Nepal, which ranged from 228-232. According to Shrestha (2008), a total of 232 species belonging to 114 genera under 36 families and 11 orders existing in culture or natural water bodies of Nepal. Recently, Shrestha and Pandit (2012) have described one more exotic species, Pangasius hypophthalmus (Sauvage), which has been commercially cultured in the terai region of Nepal since few years. This indicated that the total number of fish species present in Nepal might be more than 232.
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