16.1. Names of taxa above the rank of family are automatically typified if they are based on generic names (see Art. 10.7); for such automatically typified names, the name of a subdivision or subphylum which includes the type of the adopted name of a division or phylum, the name of a subclass which includes the type of the adopted name of a class, and the name of a suborder which includes the type of the adopted name of an order, are to be based on the generic name equivalent to that type.
Note 1. The terms "divisio" and "phylum", and their equivalents in modern languages, are treated as referring to one and the same rank. When "divisio" and "phylum" are used simultaneously to denote different ranks, this usage is contrary to Art. 5, and the corresponding names are not validly published (Art. 33.5).
16.2. Where one of the word elements -monado-, -cocco-, -nemato-, or -clado-as the second part of a generic name has been omitted before the termination -phyceae or -phyta, the shortened class name or division or phylum name is regarded as based on the generic name in question if such derivation is obvious or is indicated at establishment of the group name.
Ex. 1. Raphidophyceae Chadef. ex P. C. Silva (1980) was indicated by its author to be based on Raphidomonas F. Stein (1878).
Note 2. The principle of priority is not mandatory for
names of taxa above the rank of family (Art. 11.9).
16A.1. The name of a division or phylum is taken either from distinctive characters of the division or phylum (in descriptive names) or from a name of an included genus; it should end in -phyta, unless it is a division or phylum of fungi, in which case it should end in -mycota.
16A.2. The name of a subdivision or subphylum is formed in a similar manner; it is distinguished from a divisional name by an appropriate prefix or suffix or by the termination -phytina, unless it is a subdivision or subphylum of fungi, in which case it should end in -mycotina.
16A.3. The name of a class or of a subclass is formed in a similar manner and should end as follows:
(a) In the algae: -phyceae (class) and -phycidae (subclass);
(b) In the fungi: -mycetes (class) and -mycetidae (subclass);
(c) In other groups of plants: -opsida (class) and -idae (subclass).
16A.4. When a name has been published with a Latin termination
not agreeing with this recommendation, the termination may be
changed to accord with it, without change of author's name or
date of publication.
16B.1. In choosing among typified names for a taxon above
the rank of family, authors should generally follow the principle
of priority.