22.1. The name of any subdivision of a genus that includes the type of the adopted, legitimate name of the genus to which it is assigned is to repeat that generic name unaltered as its epithet, but not followed by an author's name (see Art. 46). Such names are termed autonyms (Art. 6.8; see also Art. 7.6).
Note 1. This provision applies only to the names of those subordinate taxa that include the type of the adopted name of the genus (but see Rec. 22A).
22.2. A name of a subdivision of a genus that includes the type (i.e. the original type or all elements eligible as type or the previously designated type) of the adopted, legitimate name of the genus is not validly published unless its epithet repeats the generic name unaltered. For the purposes of this provision, explicit indication that the nomenclaturally typical element of the genus is included is considered as equivalent to inclusion of the type, whether or not it has been previously designated (see also Art. 21.3).
Ex. 1. "Dodecatheon sect. Etubulosa" (Knuth in Engler, Pflanzenr. 22: 234. 1905) was not validly published since it was proposed for a section that included D. meadia L., the original type of the generic name Dodecatheon L.
Ex. 2. Cactus [unranked] Melocactus L. (Gen. Pl., ed. 5: 210. 1754) was proposed for one of four unranked (Art. 35.2), named subdivisions of the genus Cactus, comprising C. melocactus L. (its type under Art. 22.5) and C. mammillaris L. It is validly published, even though C. melocactus was subsequently designated as the type of Cactus L. (by Britton & Millspaugh, Bahama Fl.: 294. 1920) and, later still, C. mammillaris became the conserved type of the generic name (by the way in which the family name Cactaceae Juss. was conserved).
22.3. The first instance of valid publication of a name of a subdivision of a genus that does not include the type of the adopted, legitimate name of the genus automatically establishes the corresponding autonym (see also Art. 11.6 and 32.7).
Ex. 3. The subgenus of Malpighia L. that includes the lectotype of the generic name (M. glabra L.) is called M. subg. Malpighia, not M. subg. Homoiostylis Nied.; and the section of Malpighia including the lectotype of the generic name is called M. sect. Malpighia, not M. sect. Apyrae DC.
Ex. 4. However, the correct name of the section of the genus Rhododendron L. that includes R. luteum Sweet, the type of R. subg. Anthodendron (Rchb.) Rehder, is R. sect. Pentanthera G. Don, the oldest legitimate name for the section, and not R. sect. Anthodendron.
22.4. The epithet in the name of a subdivision of a genus may not repeat unchanged the correct name of the genus, unless the two names have the same type.
22.5. When the epithet in the name of a subdivision of a genus is identical with or derived from the epithet of one of its constituent species, the type of the name of the subdivision of the genus is the same as that of the species name, unless the original author of the subdivisional name designated another type.
Ex. 5. The type of Euphorbia subg. Esula Pers. is E. esula L.; the designation of E. peplus L. as lectotype by Croizat (in Revista Sudamer. Bot. 6: 13. 1939) has no standing.
22.6. When the epithet in the name of a subdivision of
a genus is identical with or derived from the epithet in a specific
name that is a later homonym, its type is the type of that later
homonym, whose correct name necessarily has a different epithet.
22A.1. A section including the type of the correct name of a subgenus, but not including the type of the correct name of the genus, should, where there is no obstacle under the rules, be given a name with the same epithet and type as the subgeneric name.
22A.2. A subgenus not including the type of the correct name of the genus should, where there is no obstacle under the rules, be given a name with the same epithet and type as the correct name of one of its subordinate sections.
Ex. 1. Instead of using a new epithet at the subgeneric
level, Brizicky raised Rhamnus sect. Pseudofrangula
Grubov to the rank of subgenus as R. subg. Pseudofrangula
(Grubov) Brizicky. The type of both names is the same, R. alnifolia
L'Hér.