52.1. A name, unless conserved (Art. 14) or sanctioned (Art. 15), is illegiti-mate and is to be rejected if it was nomenclaturally superfluous when pub-lished, i.e. if the taxon to which it was applied, as circumscribed by its author, definitely included the type (as qualified in Art. 52.2) of a name which ought to have been adopted, or whose epithet ought to have been adopted, under the rules (but see Art. 52.3).
52.2. For the purpose of Art. 52.1, definite inclusion of the type of a name is effected by citation (a) of the holotype under Art. 9.1 or the original type under Art. 10 or all syntypes under Art. 9.4 or all elements eligible as types under Art. 10.2; or (b) of the previously designated type under Art. 9.9 or 10.2; or (c) of the illustrations of these. It is also effected (d) by citation of the name itself, unless the type is at the same time excluded either explicitly or by implication.
Ex. 1. The generic name Cainito Adans. (1763) is illegitimate because it was a superfluous name for Chrysophyllum L. (1753), which Adanson cited as a synonym.
Ex. 2. Chrysophyllum sericeum Salisb. (1796) is illegitimate, being a superfluous name for C. cainito L. (1753), which Salisbury cited as a synonym.
Ex. 3. On the other hand, Salix myrsinifolia Salisb. (1796) is legitimate, being explicitly based upon S. myrsinites of Hoffmann (Hist. Salic. Ill.: 71. 1787), a misapplication of the name S. myrsinites L. (1753).
Ex. 4. Picea excelsa Link (1841) is illegitimate because it is based on Pinus excelsa Lam. (1778), a superfluous name for Pinus abies L. (1753). Under Picea the correct name is Picea abies (L.) H. Karst. (1881).
Ex. 5. On the other hand, Cucubalus latifolius Mill. and C. angustifolius Mill. are not illegitimate names, although Miller's species are now united with the species previously named C. behen L. (1753): C. latifolius and C. angustifolius as circumscribed by Miller (1768) did not include the type of C. behen L., which name he adopted for another species.
Ex. 6. Explicit exclusion of type: When publishing the name Galium tricornutum, Dandy (in Watsonia 4: 47. 1957) cited G. tricorne Stokes (1787) pro parte as a synonym, but explicitly excluded the type of the latter name.
Ex. 7. Exclusion of type by implication: Cedrus Duhamel (1755) is a legitimate name even though Juniperus L. (1753) was cited as a synonym; only some of Linnaeus's species of Juniperus were included in Cedrus by Duhamel, and the differences between the two genera were discussed, Juniperus (including the type of its name) being recognized in the same work as an independent genus.
Ex. 8. Exclusion of type by implication: Tmesipteris elongata P. A. Dang. (in Botaniste 2: 213. 1891) was published as a new species but Psilotum truncatum R. Br. was cited as a synonym. However, on the following page, T. truncata (R. Br.) Desv. is recognized as a different species and two pages later both are distinguished in a key, thus showing that the meaning of the cited synonym was either "P. truncatum R. Br. pro parte" or "P. truncatum auct. non R. Br."
Ex. 9. Exclusion of type by implication: Solanum torvum Sw. (Prodr.: 47. 1788) was published with a new diagnosis but S. indicum L. (1753) was cited as a synonym. In accord with the practice in his Prodromus, Swartz indicated where the species was to be inserted in the latest edition [ed. 14, by Murray] of Linnaeus's Systema vegetabilium. S. torvum was to be inserted between species 26 (S. insanum) and 27 (S. ferox), the number of S. indicum being 32. S. torvum is thus a legitimate name.
Note 1. The inclusion, with an expression of doubt, of an element in a new taxon, e.g. the citation of a name with a question mark, does not make the name of the new taxon nomenclaturally superfluous.
Ex. 10. The protologue of Blandfordia grandiflora R. Br. (1810) includes, in synonymy, "Aletris punicea. Labill. nov. holl. 1. p. 85. t. 111 ?", indicating that the new species might be the same as Aletris punicea Labill. (1805). B. grandiflora is nevertheless a legitimate name.
Note 2. The inclusion, in a new taxon, of an element that was subsequently designated as the type of a name which, so typified, ought to have been adopted, or whose epithet ought to have been adopted, does not in itself make the name of the new taxon illegitimate.
52.3. A name that was nomenclaturally superfluous when published is not illegitimate if its basionym is legitimate, or if it is based on the stem of a legitimate generic name. When published it is incorrect, but it may become correct later.
Ex. 11. Chloris radiata (L.) Sw. (1788), based on Agrostis radiata L. (1759), was nomenclaturally superfluous when published, since Swartz also cited Andropogon fasciculatus L. (1753) as a synonym. It is, however, the correct name in the genus Chloris for Agrostis radiata when Andropogon fasciculatus is treated as a different species, as was done by Hackel (in Candolle & Candolle, Monogr. Phan. 6: 177. 1889).
Ex. 12. The generic name Hordelymus (K. Jess.) K. Jess. (1885), based on the legitimate Hordeum subg. Hordelymus K. Jess. (Deutschl. Gräser: 202. 1863), was superfluous when published because its type, Elymus europaeus L., is also the type of Cuviera Koeler (1802). Cuviera Koeler has since been rejected in favour of its later homonym Cuviera DC., and Hordelymus can now be used as a correct name for the segregate genus containing Elymus europaeus L.
Note 3. In no case does a statement of parentage accompanying the publication of a name for a hybrid make the name illegitimate (see Art. H.5).
Ex. 13. The name Polypodium xshivasiae Rothm.
(1962) was proposed for hybrids between P. australe Fée
and P. vulgare subsp. prionodes (Asch.) Rothm.,
while at the same time the author accepted P. xfont-queri
Rothm. (1936) for hybrids between P. australe and P.
vulgare L. subsp. vulgare. Under Art. H.4.1,
P. xshivasiae is a synonym of P. xfont-queri;
nevertheless, it is not an illegitimate name.