International Commission on Zoological Nomenclature
 INTERNATIONAL CODE OF ZOOLOGICAL NOMENCLATURE online

Article 81. Use of the Plenary Power.

81.1. Purpose and extent. The Commission has the plenary power [Art. 78.1], on due notice as prescribed by its Constitution, to modify the application of provisions of the Code to a particular case, if such application would in its judgment disturb stability or universality or cause confusion. For the purpose of preventing such disturbance and of promoting a stable and universally accepted nomenclature, it may, by use of its plenary power, conserve, totally, partially or conditionally suppress, or give a specified precedence to, or make available any name, type fixation or other nomenclatural act, or any publication, and establish replacements.

81.2. Guiding principles. In using the plenary power, the Commission is guided by the following principles although these do not limit its use of that power.

81.2.1. If two names are homonyms the older homonym may be "totally suppressed", i.e. suppressed for the purposes of both the Principle of Priority and the Principle of Homonymy so that the later homonym may continue in use as a valid name. A species-group name which has been "totally suppressed" remains an available name [Art. 10.6] and may still denote the type species of a genus or subgenus [Art. 67.1.2].

81.2.2. If two names are objective synonyms the older synonym may be "partially suppressed", i.e. suppressed for the purposes of the Principle of Priority alone, without being suppressed also for the purposes of the Principle of Homonymy.

81.2.3. If two names are considered to be subjective synonyms the older synonym may be suppressed for the purposes of the Principle of Priority alone, as in Article 81.2.2, or it may be "conditionally suppressed" to provide that the older name may be used only when

81.2.3.1. the taxa denoted by the names are regarded as distinct, or

81.2.3.2. it is the valid name of a taxon subordinate in rank to, and included in, the taxon denoted by the later name (e.g. a subfamily within a family or a subgenus within a genus).

Example. The butterfly generic name Argynnis Fabricius, 1807 was given precedence over Argyreus Scopoli, 1777 when the latter was conditionally suppressed by the Commission under the plenary power (Opinion 161 (1945)). Argyreus is available for use for a genus distinct from Argynnis. It is also available for use as the valid name of a subgenus within Argynnis and distinct from the nominotypical subgenus.

81.2.4. If the Commission refuses to use its plenary power in a particular case, the ruling in the Opinion is to specify the name(s) to be used, and the action (if any) to be taken.