Article 31. Species-group names
31.1. Species-group names formed from personal names
A species-group name formed from a personal name may be either a noun in the genitive case, or a noun in apposition (in the nominative case), or an adjective or participle [Art. 11.9.1].
31.1.1. A species-group name, if a noun in the genitive case formed from a personal name that is Latin, or from a modern personal name that is or has been latinized, is to be formed in accordance with the rules of Latin grammar.
Examples. Margaret, if latinized to Margarita or Margaretha, gives the genitives margaritae or margarethae; similarly Nicolaus Poda, even though the name of a man, if accepted as a Latin name, gives podae; Victor and Hercules, if accepted as Latin names, give victoris and herculis; the name of Plinius, a Roman, even though anglicized to Pliny, gives plinii; Fabricius and Sartorius, if treated as Latin names, give fabricii and sartorii, but if treated as modern names give fabriciusi and sartoriusi; Cuvier, if latinized to Cuvierius, gives cuvierii.
31.1.2. A species-group name, if a noun in the genitive case (see Article 11.9.1.3) formed directly from a modern personal name, is to be formed by adding to the stem of that name -i if the personal name is that of a man, -orum if of men or of man (men) and woman (women) together, -ae if of a woman, and -arum if of women; the stem of such a name is determined by the action of the original author when forming the genitive.
Example. Under this provision, the species-group names podai from Poda, victori from Victor, and cuvieri from Cuvier are admissible. The names puckridgei and puckridgi may be formed from Puckridge.
31.1.3. The original spelling of a name formed under Articles 31.1.1 and 31.1.2 is to be preserved [Art. 32.2] unless it is incorrect [Arts. 32.3, 32.4] (for treatment of incorrect subsequent spellings of such species-group names see Articles 33.3 and 33.4).
Example. The species-group names cuvierii and cuvieri are admissible under Arts. 31.1.1 and 31.1.2 respectively, and, if available, are preserved as distinct and correct original spellings. (For homonymy between such names when combined with the same generic name, see Article 58.14).
Recommendation 31A. Avoidance of personal names as nouns in apposition. An author who establishes a new species-group name based on a personal name should preferably form the name in the genitive case and not as a noun in apposition, in order to avoid the appearance that the species-group name is a citation of the authorship of the generic name.
Examples. Gould (1841) established the specific name geoffroii in the genus Dasyurus Geoffroy, 1796. Had he proposed geoffroy as a noun in apposition, the combination Dasyurus geoffroy would have been confusing and misleading. Names such as Picumnus castelnau and Acestrura mulsant, in which the specific names are identical to personal names, are also confusing (and especially so when the specific name is wrongly given an upper case initial letter [Art. 28]).
A species-group name, if it is or ends in a Latin or latinized adjective or participle in the nominative singular, must agree in gender with the generic name with which it is at any time combined.
31.2.1. A species-group name that is a simple or compound noun (or noun phrase) in apposition need not agree in gender with the generic name with which it is combined (the original spelling is to be retained, with gender ending unchanged; see Article 34.2.1).
Examples. The specific name in Simia diana (Simia and diana both feminine) remains unchanged in Cercopithecus diana (Cercopithecus masculine); and the noun phrases in Melanoplus femurrubrum (Melanoplus masculine; but rubrum agreeing with femur, neuter) and Desmometopa m-nigrum (Desmometopa feminine; nigrum neuter, agreeing with m, because letters of the alphabet are neuter).
31.2.2. Where the author of a species-group name did not indicate whether he or she regarded it as a noun or as an adjective, and where it may be regarded as either and the evidence of usage is not decisive, it is to be treated as a noun in apposition to the name of its genus (the original spelling is to be retained, with gender ending unchanged; see Article 34.2.1).
Example. Species-group names ending in -fer and -ger may be either nouns in apposition, or adjectives in the masculine gender. Cephenemyia phobifer (Clark) has often been used as C. phobifera, but the original binomen was Oestrus phobifer; since Oestrus is masculine, phobifer in that binomen may be either a masculine adjective or a noun in apposition; hence it is to be treated as a noun in apposition and not changed when combined with the feminine generic name Cephenemyia.
31.2.3. If a species-group name (or, in the case of a compound species-group name, its final component word) is not a Latin or latinized word [Arts. 11.2, 26], it is to be treated as indeclinable for the purposes of this Article, and need not agree in gender with the generic name with which it is combined (the original spelling is to be retained, with ending unchanged; see Article 34.2.1).
Example. Species-group names such as melas, melaina, melan; polychloros, polychloron; celebrachys; nakpo (from the Tibetan word meaning black) remain unchanged when transferred from combination with a generic name of one gender to combination with one of another gender. But melaena is a latinized adjective (derived from the Greek melaina) and must be changed when so transferred, with an appropriate Latin gender ending (-us masculine, -um neuter).