The Code

This post is all about The Code. No, not the Pirate code from Pirates of the Caribbean but the code of the International Commission of Zoological Nomenclature (ICZN, 2012). This is the code that is used for determining whether a name is valid or not. It is not to be used to establish whether a particular species is unique or not. I'll try to keep it simple because like a lot of rulebooks, it can get complicated (especially when it comes to determining type specimens - more on that later).

Definition - The ICZN code is the system of scientific names to taxonomic units of extinct and extant (not extinct) animals. These units are called "taxon" when singular and "taxa" when plural. For the purposes of the Code, animal refers to members of the taxon Metazoa and any protistans regarded as animals by authors (protistans are microscopic organisms in-between algae and animals and no-one is too sure what they are)

Scope - Scientific names are those based on: actual specimens (either complete or intact), domesticated animals, names based on fossils, names based on fossilised work of animals (such as footprints, eggs, burrows etc., these are called ichnotaxa), names for groups of animals and, for those named before 1930, the work of extant animals. Additionally, the Code only really applies to names at the family, genus and species levels. Above the rank of family is not so rigorously enforced (these names are usually subject to general consensus)

Exclusions - The following are excluded from the code and hence are not regarded as valid names:

• Hypothetical concepts
• Teratological specimens (deformities, mutants, etc.)
• Hybrids
• Infrasubspecific entities (such as breeds of dogs)
• Temporary or provisional names
• After 1930, the work of extant animals
• Modifications of available names with a common suffix or prefix to indicate the group it belongs to (e.g. Herrera (1899, cited in ICZN, 2012) proposed that every genus should have a three-letter prefix to indicate class such as all insects having Ins- or all mammals having Mam- at the beginning of the name)

Independence - The code is independent of other systems. There is a separate code for plants and fungi and a separate one for Bacteria. And whilst it is acceptable for an animal to have the same name as a plant, it is not recommended.

Any name that has been regarded as an animal at any point is deemed unavailable for future use. For example, if I were to describe what I believed to be a dinosaur as Alphasaurus and it was later found to be a plant (this has actually happened) the name Alphasaurus would still be unavailable for another animal, despite the fact that it is now a plant.

Any name published after 1 January 1758 is accepted.

No name or taxonomic change made before 1758 is acceptable but information (such as descriptions and pictures) can be used

Names higher in rank than species must consist of a single word and it must be capitalised (Such as the genus for man Homo or the cow family Bovidae)

Species must consist of two names - the generic name and specific name (known as an epithet). The generic name is capitalised, the epithet is not (Such as man Homo sapiens)

Subspecies must consist of three names - again the genus is capitalised and the specific and subspecific names are not (Such as modern man Homo sapiens sapiens)

Typographical symbols such as ., ,, ? and -, do not form part of the name.

In order for a publication (and thus any new names and changes made therein) to be regarded as valid, it must adhere to the following criteria:

• it must be issued for the purpose of providing a public and permanent scientific record
• it must be obtainable, when first issued, free of charge or by purchase
• it must have been produced in an edition containing simultaneously obtainable copies by a method that assures numerous identical and durable copies and widely accessible electronic copies with fixed content and layout

The copies must be in the form of either a paper copy or, between 1986-2012, on an optical disc.

For publications that are entirely online/electronic, they will considered acceptable if:

• They were issued after 2011
• State the date the publication was published
• Are registered with ZooBank (an online repository of taxonomic changes)

The following are not considered valid publications:

• Handwritten papers (after 1930)
• Works produced by hectographing or mimeographing (1986-2012) (whatever the hell they are)
• Photographs on their own
• Proof sheets
• Microfilms
• Acoustic records of any kind
• Labels of specimens
• Preliminary versions of the work (a lot of online publications are put up before being officially published)
• Materials issued to participants at a meeting, convention, symposium etc.
• Text and illustrations distributed on the internet (unless they meet the conditions of the previous rule)
• Copies of works that have not been published (this includes PhD theses and dissertations)

As well as rules for the publication itself, there are rules for the names. For a name to be valid it must be written in the Latin alphabet (a-z). It must derive from a pre-existing language (arbitrary combinations of letters are acceptable, but only if they form a pronounceable word). For names before 1931, they must be accompanied by a description or at least a reference to one. For names between 1931-1999, they must also be accompanied with a diagnosis in order to differentiate it from other taxa. Anonymous works are valid if they were published before 1951. After 1999, all new names must be explicitly stated as such (usually by adding sp. nov. or gen. nov. or fam. nov. afterwards, nov. being short for nova, Latin for new). Family names must be listed with a type genus that best represents the group (for example the great ape family Hominidae is named after Homo, Tyrannosauridae is named after Tyrannosaurus etc.).

Names can be changed under certain circumstances such as if the gender is wrong or if the name is constantly spelled differently in the original publication (in this case, the first spelling used takes precedence, even if it was not the intended one).

When using a name, the author and date of publication should be used. Normally, if the author and date is shown in brackets, it means the taxon was placed in a different genus originally (for example, if I was to describe a new dinosaur as Betasaurus basingstokensis, it would be written as: Betasaurus basingstokensis Lucas, 2013. But if it is later re-classified it would be written as: Deltasaurus basingstokensis (Lucas, 2013)).

The most important part of the Code is the Principle of Priority. This states that the oldest valid name is to be used. For example, if Gammasaurus Lucas, 2011 and Epsilonsaurus, Lucas, 2013, were found to be the same, Gammasaurus would be the correct name to be used because it is older. This also applies to identical names (called homonyms). For example, if there was a Zetasaurus, Smith, 1930 and then decades later a Zetasaurus, Lucas, 2013, Lucas' Zetasaurus would have to be re-named because it is younger. This applies even if the older name is no longer valid. For example, even though Brontosaurus is no longer a valid taxon, the name can never be used again. If two names were published at the same time and found to be synonymous, the author who discovered this can choose which name to use (this is known as the First Reviser Rule). For example, Tyrannosaurus and Dynamosaurus were both named by Osborn in 1905. The following year, he announced they were the same, and since they were named at the same time, Osborn chose Tyrannosaurus to be the correct name (he could have quite easily chosen Dynamosaurus and that would have been the most famous dinosaur name instead). 

The first time a taxon is mentioned in a paper, it must be written out in full. It can then be abbreviated afterwards. For example, if I was to write an article describing Etasaurus cornwallensis I would write it out in full, but after that, I can refer to it as E. cornwallensis (although, I don't personally like abbreviating taxa). No diacritics, marks, punctuation or symbols may be used. Hyphens can be used in some circumstances. For example, if I wanted to name a species of Thetasaurus after St. Austell, I would not be able to use the "." after St in the name. So it would become Thetasaurus staustellensis. 

Family group names have specific suffixes depending on their rank. -oidea for superfamilies, -idae for families, -inae for subfamilies, -ini for tribes and -ina for subtribes. Generic and species names must have the same gender endings (generally -us is masculine, -a is feminine and -um is neutral, though there are exceptions). For example Iotasaurus is masculine and needs a masculine species name, Kappasaura is feminine and needs a feminine species name and Lambdasaurum is neutral and so needs a neutral species name. Species names can be modified is the new generic name has a different gender. For example, if Musaurus cristatus (a masculine name) is reclassified into Nusaura, cristatus would have to change to cristata. The original spellings must be used, even if they are technically incorrect. For example, if Xisaurus senai was named after John Cena, the original senai spelling must be used. The only exceptions to this is if the original name is invalid because it contains accents, punctuation marks, numerals etc. 

That's about it. Not much more to say. Sorry it's a bit wordy but it's an important aspect of science and it's best to get it over now then keep referring to it in posts. My next non-dinosaur post will be about Butterflies. Next week will see the much-anticipated part 2 of Tyrannosaurus rex.

See also:
More dinosaurs

References:
ICZN (2012) 'International Code of Zoological Nomenclature', [Online], Available at: http://www.nhm.ac.uk/hosted-sites/iczn/code/, Accessed on: 06/06/2013