PhyloCode

The International Code of Phylogenetic Nomenclature, known as the PhyloCode for short, is a developing draft for a formal set of rules governing phylogenetic nomenclature. Its current version is specifically designed to regulate the naming of clades, leaving the governance of species names up to the rank-based Nomenclature codes (ICN, ICZN, ICNB, ICTV). The International Code of Phylogenetic Nomenclature, known as the PhyloCode for short, is a developing draft for a formal set of rules governing phylogenetic nomenclature. Its current version is specifically designed to regulate the naming of clades, leaving the governance of species names up to the rank-based Nomenclature codes (ICN, ICZN, ICNB, ICTV). The PhyloCode is associated with the International Society for Phylogenetic Nomenclature (ISPN). Its companion volume, Phylonyms, will establish the first taxon names under PhyloCode, serving as examples for those unfamiliar with the code. RegNum is an associated online database for Phylogenic names. The PhyloCode proposes to regulate phylogenetic nomenclature by providing rules for how to decide which associations of names and definitions will be considered established, which of those will be considered homonyms or synonyms, and which one of a set of synonyms or homonyms will be considered accepted (generally the one registered first; see below). The PhyloCode will only allow the naming of clades, not of paraphyletic or polyphyletic groups, and will only allow the use of specimens, species, and apomorphies as specifiers (anchors). Unlike rank-based nomenclatural codes (ICN, ICZN, ICNB), the PhyloCode does not require the use of ranks, although it does optionally allow their use. The rank-based codes define taxa using a rank (such as genus, family, etc.) and, in many cases, a type specimen or type subtaxon. The exact content of a taxon, other than the type, is not specified by the rank-based codes. In contrast, under phylogenetic nomenclature, the content of taxa are delimited using a definition that is based on phylogeny (i.e., ancestry and descent) and uses specifiers (e.g., species, specimens, apomorphies) to indicate actual organisms. The formula of the definition indicates an ancestor. The defined taxon, then, is that ancestor and all of its descendants. Thus, the content of a phylogenetically defined taxon relies on a phylogenetic hypothesis. The following are examples of types of phylogenetic definition (capital letters indicate specifiers): Other types of definition are possible as well, taking into account not only organisms' phylogenetic relations and apomorphies but also whether or not related organisms are extant. The following table gives examples of phylogenetic definitions of clades that also have ranks in traditional nomenclature. When all the specifiers in a node-based definition are extant specimens or species, as in the following definition of Mammalia, a crown group is defined. (The traditional definition of Mammalia is less restrictive, including some fossil groups outside of the crown group.) The draft of the PhyloCode has gone through several revisions. All older versions can be found on the website. As of April 2019, the current version is 5, finalized January 2014 and released 21 January 2019.