Article 45. The species group.

45.1. Definition. The species group encompasses all nominal taxa at the ranks of species and subspecies (see also Article 10.2).

45.2. Provisions applicable to all species-group nominal taxa and their names. Species-group nominal taxa and their names are subject to the same provisions irrespective of rank within the species group, except when these apply explicitly to names at one rank alone (for interpolated names to denote aggregates of species or subspecies see Article 6.2).

45.3. Application of species-group names. The application of each species-group name is determined by reference to the name-bearing type [Arts. 61, 71 to 75] of the nominal taxon denoted by the combination in which the species-group name was established.

45.4. Formation and treatment of species-group names. A species-group name is to be formed and treated in accordance with Article 11 and the relevant provisions of Articles 19, 20, 23 to 34.

45.5. Infrasubspecific names. A name expressly proposed to denote an infrasubspecific entity (see Glossary) is not an available name unless the provisions of Article 45.6 specify otherwise; it is excluded from the species group and is not regulated by the Code [Art. 1.3.4]. A fourth name published as an addition to a trinomen automatically denotes an infrasubspecific entity (however an interpolated species-group name [Art. 6.2] is not regarded as an addition to a trinomen).

45.5.1. A name that has infrasubspecific rank under the provisions of this Article cannot be made available from its original publication by any subsequent action (such as "elevation in rank") except by a ruling of the Commission. When a subsequent author applies the same word to a species or subspecies in a manner that makes it an available name [Arts. 11-18], even if he or she attributes authorship of the name to the author of its publication as an infrasubspecific name, that subsequent author thereby establishes a new name with its own authorship and date.

Example. The name ferganensis in Vulpes vulpes karagan natio ferganensis (published by Ognev, 1927) is an addition to a trinomen and hence infrasubspecific; it is available from, and should be attributed to, Flerov (1935) who first used it for a subspecies, Vulpes vulpes ferganensis.

45.6. Determination of subspecific or infrasubspecific rank of names following a binomen. The rank denoted by a species-group name following a binomen is subspecific, except that

45.6.1. it is infrasubspecific if its author expressly gave it infrasubspecific rank, or if the content of the work unambiguously reveals that the name was proposed for an infrasubspecific entity (see also Article 45.6.4);

45.6.2. it is deemed to be infrasubspecific if its author used one of the terms "aberration", "ab." or "morph";

Example. The name pallasi in Arvicola amphibius ab. pallasi published by Ognev (1913) is infrasubspecific; it is available as a species-group name from, and should be attributed to, Ognev (1950) who first used it for a subspecies, Arvicola terrestris pallasi.

45.6.3. it is deemed to be infrasubspecific if it was first published after 1960 and the author expressly used one of the terms "variety" or "form" (including use of the terms "var.", "forma", "v." and "f.");

45.6.4. it is subspecific if first published before 1961 and its author expressly used one of the terms "variety" or "form" (including use of the terms "var.", "forma", "v." and "f."), unless its author also expressly gave it infrasubspecific rank, or the content of the work unambiguously reveals that the name was proposed for an infrasubspecific entity, in which case it is infrasubspecific [see also Art. 45.6.1]; except that

45.6.4.1. a name that is infrasubspecific under Article 45.6.4 is nevertheless deemed to be subspecific from its original publication if, before 1985, it was either adopted as the valid name of a species or subspecies or was treated as a senior homonym.

Examples. Spencer (1896) described and named Sminthopsis murina var. constricta, a small carnivorous marsupial, from a specimen which he considered morphologically intermediate between two congeneric species, Sminthopsis murina and S. crassicaudata; his work does not unambiguously reveal that the name was proposed for an infrasubspecific entity, and accordingly constricta has subspecific rank from its original publication.

In the Heteroptera, Westhoff (1884) explicitly gave the name Pyrrhocoris apterus var. pennata to a macropterous form as such, and Wagner (1947) explicitly gave the name Stenodema trispinosum f. pallescens to freshly emerged adults as such; the names pennata and pallescens are therefore of infrasubspecific rank, and since neither was adopted for a species or subspecies before 1985 they are both unavailable.

Polinski (1929) described a terrestrial gastropod Fruticicola unidentata subtecta as a "variété (natio) n.", explicitly stating that it was only "une forme" which did not merit subspecific rank. However, Klemm (1954) adopted Trichia (Petasina) unidentata subtecta (Polinski) as the valid name of a subspecies, and the subspecific name subtecta is therefore deemed to be available from Polinski, 1929.