Nomenclature Codes

The Nomenclature Codes (or "the Codes of nomenclature") are the rulebooks that govern biological nomenclature.

After the successful introduction of two-part names for species by Linnaeus it became ever more apparent that a detailed body of rules was necessary to govern scientific names. From the mid-nineteenth century onwards there were several initiatives to arrive at worldwide-accepted sets of rules. In the course of time these became the present Nomenclature Codes governing the naming of
 * animals (International Commission on Zoological Nomenclature abbrev. ICZN)
 * plants (incl. Fungi, cyanobacteria) (International Code of Botanical Nomenclature abbrev. ICBN with supplementary Codes)
 * bacteria (International Code of Nomenclature of Bacteria abbrev. ICNB)
 * viruses (see virus classification).

Starting point
The starting point, that is the time from which these Codes are in effect (usually retroactively), varies from group to group, and sometimes from rank to rank. In botany the starting point will often be 1753, in zoology 1758. On the other hand bacteriology started anew, making a clean sweep in 1980, although maintaining the original authors and dates of publication.

Workings
There are also differences in the way Codes work. For example, the ICBN (the plant Code) forbids tautonyms, while the ICZN, (the animal Code) allows them.

Terminology
These Codes differ in terminology, and there is a long-term project to "harmonize" this. For instance, the ICBN uses "valid" in "valid publication of a name" (= the act of publishing a formal name), with "establishing a name" as the ICZN equivalent. The ICZN uses "valid" in "valid name" (="correct name"), with "correct name" as the ICBN equivalent. Harmonization is making very limited progress.

Types
The codes differ in terms of what kinds of types are permissible. The bacteriological code generally requires living type cultures. The botanical code requires dried specimens (typically in an herbarium), or sometimes drawings. There has been ongoing debate regarding which kind of type is more useful in a case like cyanobacteria. The zoological code generally requires a dead preserved animal, but sometimes allows a living type.

Other codes
A more radical approach is to replace all existing Codes by a BioCode, basically a synthesis of the existing Codes. The BioCode draft has received little attention since 1997; its originally planned implementation date of January 1, 2000, has passed unnoticed. However, a 2004 paper concerning the cyanobacteria does advocate a future adoption of a BioCode and interim steps consisting of reducing the differences between the codes.

Another code in development is the PhyloCode, which regulates phylogenetic nomenclature rather than Linnaean nomenclature (that is, it requires phylogenetic definitions for every name, and does not contain mandatory ranks). Implementation is tentatively scheduled for sometime before 2010.

The formal names of cultivated plants are governed by the ICNCP. This code operates within the limits set by the ICBN, but uses different basic principles.