REJECTION OF NAMES

A legitimate name must not be rejected merely because it, or its epithet, is inappropriate or disagreeable, or because another is preferable or better known or because it has lost its original meaning. A name is rejected under one or more of the following situations: 

1. Nomen nudum (nom. nud.): Nomen nudum is a designation of a new taxon published without a description or diagnosis or reference to a description or diagnosis. • Many names published by Wallich in his Catalogue (abbreviated Wall. Cat.) published in 1812 were nomen nudum. These were either validated by another author at a later date by providing a description (e.g. Cerasus cornuta Wall. ex Royle) or if by that time the name has already been used for another species by some other author, the nomen nudum even if validated is rejected and a new name has to be found. For example, Quercus dilatata Wall., a nom. nud. rejected and replaced by Q. himalayana Bahadur, 1972.

2. Name not effectively published, not properly formulated, lacking typification or without a Latin diagnosis. 

3. Tautonym: Tautonym is a binary designation in which the specific epithet exactly repeats the generic name. Whereas the Zoological Code allows binomials with identical generic name and specific epithet (e.g. Bison bison), such names in Botanical nomenclature constitute tautonyms (e.g. Malus malus), and are rejected. – The words in the tautonym are exactly identical, and evidently names such as, Cajanus cajan or Sesbania sesban are not tautonyms and thus legitimate. – Repetition of a specific epithet in an infraspecific epithet does not constitute a tautonym but a legitimate autonym (e.g. Acacia nilotica ssp. nilotica).

4. Later homonym:

Homonym is a name spelled exactly like another name published for a taxon of the same rank based on a different type.

• A taxon should have one correct name, and the Code does not allow the same name to be used for two different species (or taxa). Such, if existing, constitute homonyms. The one published at an earlier date is termed the earlier homonym and that at a later date as the later homonym. The Code rejects later homonyms. For example,

Ziziphus jujuba Lam., 1789 had long been used as the correct name for the cultivated fruit jujube. This, however,

was ascertained to be a later homonym of a related species Z. jujuba Mill., 1768. The binomial Z. jujuba Lam.,

1789 is thus rejected and jujube correctly named as Z. mauritiana Lam., 1789.

• When two or more generic or specific names based on different types are so similar that they are likely to be confused (because they are applied to related taxa or for any other reason) they are to be treated as homonyms.

Names treated as homonyms include:

Asterostemma Decne. (1838) and Astrostemma Benth. (1880);

Pleuropetalum Hook. f. (1846) and Pleuripetalum T. Durand (1888);

Skytanthus Meyen (1834) and Scytanthus Hook. (1844).

The three generic names Bradlea Adans. (1763), Bradleja Banks ex Gaertn. (1790), and Braddleya Vell. (1827),

all commemorating Richard Bradley, are treated as homonyms because only one can be used without serious risk of confusion.

5. Later isonym: Isonym is the same name based on the same type, published independently at different times by different authors. When the same name, based on the same type, has been published independently at different times by different authors, then only the earliest of these ‘isonyms’ has nomenclatural status. The name is always to be cited from its original place of valid publication, and later ‘isonyms’ will be ignored. For example, Baker (1892) and Christensen (1905) independently published the name Alsophila kalbreyeri as a substitute for A. podophylla Baker (1891) non Hook. (1857). As published by Christensen, Alsophila kalbreyeri is a later ‘isonym’ of A. kalbreyeri Baker, without nomenclatural status it has been rejected.

6. Nomen superfluum (nom. superfl.): A name is illegitimate and must be rejected when it was nomenclaturally superfluous when published, i.e., if the taxon to which it was applied – as circumscribed by its author – included the type of a name or epithet which ought to have been adopted under the rules. For example, Physkium natans Lour., 1790 when transferred to the genus Vallisneria, the epithet natans should have been retained but de Jussieu used the name Vallisneria physkium Juss., 1826 a name which becomes superfluous. The species has accordingly been named correctly as Vallisneria natans (Lour.) Hara, 1974. 

7. Nomen ambiguum (nom. ambig.): A name is rejected if it is used in a different sense by different authors and has become a source of persistent error. For example, Rosa villosa L. is rejected because it has been applied to several different species and has become a source of error.

8. Nomen confusum (nom. confus.): A name is rejected if it is based on a type consisting of two or more entirely conflicting elements, so that it is difficult to select a satisfactory lectotype. For example, the characters of the genus Actinotinus, were derived from two genera Viburnum and Aesculus, owing to the insertion of the inflorescence of Viburnum in the terminal bud of an Aesculus by a collector. The name Actinotinus must, therefore, be abandoned. 

9. Nomen dubium (nom. dub.): A name is rejected if it is dubious, i.e. it is of uncertain application because it is impossible to establish the taxon to which it should be referred. For example, Linnaeus (1753) attributed the name Rhinanthus crista-galli to a group of several varieties, which he later described under separate names, rejecting the name R. crista-galli L.