H.5.1. The appropriate rank of a nothotaxon is that of the postulated or known parent taxa.
H.5.2. If the postulated or known parent taxa are of unequal rank the appropriate rank of the nothotaxon is the lowest of these ranks.
Note 1. When a taxon is designated by a name in a rank inappropriate to its hybrid formula, the name is incorrect in relation to that hybrid formula but may nevertheless be correct, or may become correct later (see also Art. 52 Note 3).
Ex. 1. The combination Elymus xlaxus (Fr.) Melderis & D. C. McClint. (1983), based on Triticum laxum Fr. (1842), was published for hybrids with the formula E. farctus subsp. boreoatlanticus (Simonet & Guin.) Melderis x E. repens (L.) Gould, so that the combination is in a rank inappropriate to the hybrid formula. It is, however, the correct name applicable to all hybrids between E. farctus (Viv.) Melderis and E. repens.
Ex. 2. Radcliffe-Smith incorrectly published the nothospecific
name Euphorbia cornubiensis Radcl.-Sm. (1985) for
E. amygdaloides L. x E. characias subsp. wulfenii
(W. D. J. Koch) Radcl.-Sm., although the correct designation for
hybrids between E. amygdaloides and E. characias
L. is E. martini Rouy (1900); later, he remedied
his mistake by publishing the combination E. martini
nothosubsp. cornubiensis (Radcl.-Sm.) Radcl.-Sm. (in Taxon
35: 349. 1986). However, the name E. cornubiensis
is potentially correct for hybrids with the formula E. amygdaloides
E. wulfenii W. D. J. Koch.
H.5A.1. When publishing a name of a new nothotaxon at the
rank of species or below, authors should provide any available
information on the taxonomic identity, at lower ranks, of the
known or postulated parent plants of the type of the name.