There are many reasons why we have many more names than there are species.
Most extra names come from the different ways that people refer to species. Some names ar e scientific, are in Latin, and follow conventions that can be found in the codes of nomenclature. Others are common names. Even though scientific names are regulated by the codes of nomenclature, they can appear in many different forms. 'Grevillea glauca', 'G. glauca', 'Grevillea glauca Banks & Sol. ex Knight', 'Grevillea glauca Banks and Solander 1809' are all legitimate ways of writing out the scientific name for the Australian shrub that is used for boomerangs or to assist in hanging out the washing. Although biologists know that these names refer to the same species, a computer registers that the names are different and makes the assumption that they refer to different species.
When Linnaeus created the foundations of contemporary biological classification in the 18th century, he only distinguished about 10,000 species, and placed them in about 1300 genera. In the expansion to the current number, scientists have tried to refine and debate what species are as they learn more about the nature and evolution of them. They move species from one genus to another in order that closely related species are grouped together. As the names of species contain one word for the species and another for the genus in which the species, these moves create new names for the species. The yellow fever mosquito was described by Linnaeus as Culex aegypti, then became known as Aedes aegypti, and more recently was transferred to Stegomyia, to give it yet another name, Stegomyia aegypti. Although the species is unchanged, we have several names for it.
Two solutions are normally applied to 'many-names-for-one-species' problem. The first is to identify the most correct name and seek universal adoption of it. The alternative is reconciliation - a process by which alternative names for the same entity are groups together. Reconciliation includes scientific names, vernacular names, and surrogates for names. Users and managers of biological information rarely have the capacity to edit names - especially those of earlier documents. This precludes the first option and imposes on GNA a requirement to include reconciliation.
Any name may exist in a number of lexical variants, and groups of those lexical variants are a critical component of reconciliation groups.
There are many reasons why an organism may have more than one name. The same species might have scientific names, and vernacular names, and perhaps even surrogates for names surrogates. Scientific names can be presented in different formats: H. sapiens, and Homo sapiens Linn. are alternative and legitimate forms of the name. Names may be often mis-spelled. Taxonomic research often results in a species being moved from one genus to another. An example is the yellow fever mosquito. It was described by Linnaeus with the name Culex aegypti, then became known as Aedes aegypti, and more recently was transferred to Stegomyia, to give it yet another name, Stegomyia aegypti. Although the species is unchanged, we have several names for it.
Finally, different authors may judge that two species initially described independently of each other, are in fact the same species. The highly modified coelenterate, Myxobolus cerebralis, that infects the brains of salmonids, disturbs their behaviour and affects their lives. The literature also contains descriptions of two other organisms: Triactinomyxon dubium and T. gyrosalmo. Towards the end of the last century it became clear that the things that had been described as Triactinomyxon were part of the life cycle of Myxobolus cerebralis. All names therefore referred to one species. As species can only have one name, Triactinomyxon dubium and Triactinomyxon gyrosalmo became synonyms of Myxobolus cerebralis, As the three names were created independently with difference reference material, the synonyms are referred to as heterotypic or subjective.
Reconciliation groups include lexical variants of names, the nomenclatural variants that form homotypic or objective synonyms, opinions and concepts that embrace subjective or heterotypic synonyms, vernacular names, and surrogates (such as specimen numbers or barcodes) for the same taxa. Flags can be added to names to indicate special status such as the nomenclaturally correct scientific name. A particular example is given to the right.