International Code of Phylogenetic Nomenclature (PhyloCode)

Division II. Rules

Chapter VII. Orthography

Article 17. Orthographic Requirements for Establishment


In order to be established, a clade name must be a single word and begin with a capital letter. The name must be composed of more than one letter and consist exclusively of letters of the Latin alphabet as used in contemporary English, which is taken to include the 26 letters a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, and z, even though some of these letters are rare or absent in classical Latin. If other letters, ligatures, numerals, apostrophes, or diacritical signs that are foreign to classical Latin appear in a name, it cannot be established. A hyphen may be included in a clade name only when it is a panclade name (see Art. 10.3), or the name has an apomorphy-based definition and is formed in accordance with Article 10.8, or the name is based on the preexisting name of a subdivision of a genus (see Rec. 10F), or the name is based on a preexisting name preceded by a taxon-related prefix such as Phyto-, Phyco-, Myco-, Prokaryo-, or Zoo- in the situation covered by Recommendation 10D. When other letters, ligatures, or diacritical signs appear in the protologue of a preexisting name, they must be transliterated at the time of conversion in conformity with the rank-based code that is applicable to the clade concerned. Hyphens or apostrophes present in a preexisting name must be deleted at the time of conversion. See Note 18.1.2 for the inclusion of diaereses and apostrophes as optional pronunciation guides in the subsequent use of established names.


When a preexisting name has been published in a work where the letters u and v or i and j are used interchangeably, or are used in any other way incompatible with modern practices (e.g., one of those letters is not used or is used only when capitalized), those letters must be transliterated at the time of conversion in conformity with modern usage.

Example 1

Vffenbachia Fabr. (1763) would be changed to Uffenbachia when converted.


A clade name may be a word in or derived from Latin, Greek, or any other language provided that the name uses the Latin alphabet (Art. 17.1).

Recommendation 17.3A

If a clade name is derived from a language other than Latin, it should be Latinized, in the tradition of scientific names governed by the ICNAFP, ICZN, etc.

Recommendation 17.3B

In order to avoid confusion with vernacular and informal names, a new clade name should not be spelled identically to a vernacular or informal name in any modern language. However, the scientific name may be derived from the vernacular or informal name by Latinization.

Example 1

“Tricolpates” (a plant clade) is an informal name and should therefore not be adopted as the formal scientific name for this (or any other) clade. However, a name derived by Latinizing “tricolpates” (e.g., Tricolpatae) may be used.


If a clade is named after a person, the clade name, in order to be established, must differ in spelling from the person’s name, for example through the addition of a Latinized ending.

Example 1

If a clade is named in honor of a person whose surname is Woodson, the clade name must not be Woodson but may be Woodsonia.


In order to be established, the spelling of a converted name must be identical to that of the preexisting name on which it is based, except as noted in Articles 17.1 and 17.2.

Recommendation 17.5A

When a preexisting name is converted, the spelling in prevailing use should be retained. As a general guideline, adoption of a spelling by two-thirds of the authors who have used the name in the past 25 years would qualify as prevailing use. If it is not clear which spelling is the prevailing one, the original spelling should be adopted for the converted name, except for the correction of orthographical (including typographical) errors and the mandatory corrections imposed under Articles 17.1 and 17.2. In this code, the original spelling is the one used in the protologue.

Recommendation 17A

Names established under this code should be pronounceable. Thus, every syllable should contain a vowel (or diphthong), and combinations of consonants that do not generally occur in either Latin or English should be avoided unless they are contained within the name of a person, place, or other entity after which a clade is named.

Recommendation 17B

New clade names should follow the rules and recommendations of the appropriate rank-based code with regard to Latin grammar. However, failure to follow those rules and recommendations does not invalidate the establishment of names under this code.