International Commission on Zoological Nomenclature
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Article 73. Name-bearing types fixed in the original publication (holotypes and syntypes).

73.1. Holotypes. A holotype is the single specimen upon which a new nominal species-group taxon is based in the original publication (for specimens eligible to be holotypes in colonial animals and protistans, see Articles 72.5.2, 72.5.4 and 73.3).

73.1.1. If an author when establishing a new nominal species-group taxon states in the original publication that one specimen, and only one, is the holotype, or "the type", or uses some equivalent expression, that specimen is the holotype fixed by original designation.

73.1.2. If the nominal species-group taxon is based on a single specimen, either so stated or implied in the original publication, that specimen is the holotype fixed by monotypy (see Recommendation 73F). If the taxon was established before 2000 evidence derived from outside the work itself may be taken into account [Art. 72.4.1.1] to help identify the specimen.

73.1.3. The holotype of a new nominal species-group taxon can only be fixed in the original publication and by the original author (for consequences following a misuse of the term "holotype" see Article 74.6).

73.1.4. Designation of an illustration of a single specimen as a holotype is to be treated as designation of the specimen illustrated; the fact that the specimen no longer exists or cannot be traced does not of itself invalidate the designation.

73.1.5. If a subsequent author finds that a holotype which consists of a set of components (e.g. disarticulated body parts) is not derived from an individual animal, the extraneous components may, by appropriate citation, be excluded from the holotype (material may be excluded from a hapantotype if it is found to contain components representing more than one taxon [Art. 73.3.2]).

Recommendation 73A. Designation of holotype. An author who establishes a new nominal species-group taxon should designate its holotype in a way that will facilitate its subsequent recognition.

Recommendation 73B. Preference for specimens studied by author. An author should designate as holotype a specimen actually studied by him or her, not a specimen known to the author only from descriptions or illustrations in the literature.

Recommendation 73C. Data on the holotype. An author who establishes a new nominal species-group taxon should publish at least the following data concerning the holotype, if they are relevant and known to the author:

73C.1. its size or the size of one or more relevant organs or parts;

73C.2. the full locality (including geographic coordinates), date, and other data on the labels accompanying it;

73C.3. its sex, if applicable;

73C.4. its developmental stage, and its caste, if the taxon includes more than one caste;

73C.5. the name of the collector;

73C.6. the collection in which it is situated and any collection number or register number assigned to it;

73C.7. in the case of a parasite, the name of the host species;

73C.8. in the case of an extant terrestrial taxon, the elevation in metres above sea level at which the holotype was taken;

73C.9. in the case of an extant aquatic taxon, the depth in metres below water level at which the holotype was taken;

73C.10. in the case of a fossil taxon, the geological age and stratigraphical position of the holotype, stated, if possible, in metres above or below a well-established plane.

Recommendation 73D. Labelling of paratypes. After the holotype has been labelled, any remaining specimens of the type series [Art. 72.4.5] should be labelled "paratype" to identify the components of the original type series.

Recommendation 73E. Avoidance of the term "cotype". An author should not use the term "cotype", e.g. in the sense of syntype or paratype.

Recommendation 73F. Avoidance of assumption of holotype. Where no holotype or syntype was fixed for a nominal species-group taxon established before 2000, and when it is possible that the nominal species-group taxon was based on more than one specimen, an author should proceed as though syntypes may exist and, where appropriate, should designate a lectotype rather than assume a holotype (see also Article 74.6).

73.2. Syntypes. Syntypes are specimens of a type series that collectively constitute the name-bearing type. They may have been expressly designated as syntypes (see Article 73.2.1 for acceptable terms); for a nominal species-group taxon established before 2000 [Art. 72.3] all the specimens of the type series are automatically syntypes if neither a holotype [Art. 72.1] nor a lectotype [Art. 74] has been fixed. When a nominal species-group taxon has syntypes, all have equal status in nomenclature as components of the name-bearing type.

73.2.1. Syntypes may include specimens labelled "cotype" or "type" (both used in the meaning of syntype), specimens with no identifying label, and specimens not seen by the author but which form the bases of previously published descriptions or illustrations upon which the author founded the new nominal species-group taxon in whole or in part [Art. 72.5.5].

73.2.1.1. When a nominal taxon is established after 1999, only those specimens expressly indicated by the author as those upon which the new taxon is based (see Article 72.3) are syntypes.

73.2.2. Specimens that were syntypes prior to the valid designation of a lectotype [Art. 74] are no longer syntypes after such designation; by that action they become lectotype and paralectotypes (see Recommendation 74F); the latter have no name-bearing function and do not regain status as syntypes if the lectotype is lost or destroyed.

73.2.3. If all syntypes of a nominal species-group taxon have the same place of origin [Art. 76.1] that is the type locality; but if the syntypes originated from two or more localities (including different strata), the type locality encompasses all of the places of origin. If a lectotype is subsequently designated, the type locality is the place of origin of the lectotype [Art. 76.2].

73.3. Hapantotypes. A hapantotype (see Glossary) consisting of one or more preparations or cultures may be designated when a nominal species-group taxon of extant protistans is established. This hapantotype is the holotype of the nominal taxon.

73.3.1. A hapantotype, although consisting of a number of separate organisms, is deemed to be indivisible and cannot be restricted by lectotype selection; but

73.3.2. if a hapantotype is found to contain individuals of more than one species-group taxon, components may, by appropriate citation, be excluded from it until it contains individuals of only one species-group taxon (for the treatment of holotypes found to consist of components derived from more than one individual, see Article 73.1.5.).