Species and scientific names

Taxonomy and nomenclature

Pultenaea procumbens A.Cunn. - Photo CC By Donald Hobern

Species and scientific names

Before using COL, it is helpful to understand the basics of how species are named and how taxonomists work with scientific names. Although this page focuses on species names, the same principles apply to the scientific names given to other taxonomic units (taxa) such as kingdoms, families and genera.

How taxonomists name species

Taxonomists study the variation between individual organisms within their group of interest and seek to interpret this as the result of evolution. Most importantly, taxonomists aim to assign organisms to species and other named taxa. In most cases, a taxonomist will name a new species when they find a set of related individuals that do not freely inter-breed with individuals of any other species. In many cases, such decisions will be very complex and may use different criteria, but the goal is always to recognise species that are truly distinct from others.

Rules for creating species names

Rules have been established for formal naming of species in each kingdom. Animal names are controlled by the International Code of Zoological Nomenclature (ICZN), botanical and fungal names by the International Code of Nomenclature for algae, fungi and plants (ICN), names of bacteria and Archaea by the International Code of Nomenclature of Prokaryotes (ICNP), and virus names by the International Code of Virus Classification and Nomenclature (ICVCN). Each of these codes gives the rules for valid publication of new names for organisms within its scope. Taxonomists are responsible for following these rules. If the rules are followed correctly, the newly published scientific name is added to the literature and becomes available for future researchers to use. Rules also exist to deal with correcting certain mistakes in practice or to suppress names that are problematic. The process that follows these semi-legal rules for naming organisms is referred to as nomenclature. As will be seen below, nomenclature should not be confused with taxonomy.

Information associated with species names

Every publication that includes new species names must include descriptive information to separate each species from others in the group. It must also identify a type specimen that will serve as the primary example for the species. No matter how much future researchers change their understanding of the evolution and classification of the taxonomic group in question, the species name will always remain associated with the type specimen. The publication must also place the new species in a genus to show how it is related to other species. Each genus will itself be placed within a series of more encompassing higher-ranked taxa. If these placements reflect evolutionary history, each higher-ranked taxon will include all species that share a successively older common ancestor. Under most of the nomenclatural codes, species receive a binomial name that includes the genus name as its first part and a distinctive specific epithet as the second. This is not the case for virus names.

Changes in names over time

As taxonomists continue to study the group, they may conclude that two named species are not really distinct from each other, or that a single name actually encompasses several species that should each have their own names, or that the relationships between species are better represented using a different classification, i.e. a different arrangement of genera and higher taxa. The rules of nomenclature do not control these decisions, which are instead part of the work of taxonomy and are to be made based on the best scientific judgment of responsible taxonomists. However nomenclatural codes do establish how existing names are to be handled under these circumstances. In particular, an existing binomial may be modified by combining the specific epithet with a new genus name. For example, in 1771, Linnaeus gave the name Felis concolor to the Puma, placing it with other cats in the genus_Felis_. Today, we consider this species sufficiently distinct to placed it as the only living member of the genus Puma. The accepted name for this species is therefore now Puma concolor (Linnaeus, 1771).

Over time, many scientific names that are considered fully valid from a nomenclatural standpoint are no longer considered current or accepted by taxonomists working with the group. These names are now synonyms for an accepted species name.

Organising data on names and species

COL brings together information that summarises nomenclatural actions (published names, decisions on questionable names, etc.) and taxonomic judgments (decisions to synonymise species names, changes in classification, etc.) and organises it as a public resource. When COL is complete for a given group, a user can find all published scientific names for the group and whether modern taxonomists see each of these historical names as an accepted name or as a synonym for a different species. Through ChecklistBank, COL also gives access to a wide range of historical, regional or other taxonomic viewpoints on these same names.

Facts and hypotheses

The distinction between nomenclature, as the formal process for publishing names, and taxonomy, as ongoing research into the relationships between organisms and how they should be grouped into taxa, is important.

Although errors exist in databases, information on any published name (nomenclature) comprises a set of verifiable object facts (a given author published the name on a particular page of a given publication, etc.). This means that it would be possible for a single database accurately — and without debate — to hold everything we need to know about all names published under any code. COL works with the centres that seek to maintain such databases for each code, known as nomenclators. These include ZooBank for animal names, the International Plant Name Index for plant names, Index Fungorum for fungal names, Prokaryotic Nomenclature Up-to-date for bacterial names and the International Committee on Taxonomy of Viruses for viral names. COL does not wish to maintain a separate version of the nomenclatural data for each kingdom and is working with these partners to use their reference databases as the official points of truth for this information.

On the other hand, when taxonomists decide how to represent the variation within any taxonomic group as a set of named species and a classification, these decisions are hypotheses that may be updated over time as new evidence appears or as future researchers reinterpret the evidence. This means that different taxonomists may create alternative species lists for the same group. Although the nomenclators can aim to become final and factually accurate databases for names, it is not possible to deliver such a database for species concepts. Catalogue of Life works with taxonomic communities to develop adopt and modern consensus-based species lists for each taxonomic group.