RULKS FOR NOMENCLATURE 17 



the original name must be retained for the part in which the type species, 

 genus, or family remains. 



When a species is transferred to another genus than that under which 

 it was first described, or when for any other valid reason the generic 

 name is changed, the specific epithet must be retained, subject to change 

 of gender in case it is an adjective, if the new genus name is of different 

 gender. Exceptions are as follows: If the new genus name is the same as 

 the specific epithet or if in the new genus a similar combination already 

 exists (e.g., when Leontodon taraxacum was split off from the genus 

 Leontodon and placed in the new genus Taraxacum, the epithet had to be 

 replaced; Uredo sorghi (1897) was transferred to the genus Puccinia, but 

 as there was already a Puccinia sorghi (1832), another epithet had to be 

 chosen). In this case the oldest available epithet of a synonym must be 

 taken or in lack of such a name a new epithet must be provided by the 

 author making the transfer. 



In describing a species de novo the describer's (abbreviated) name 

 follows the specific epithet, but if an author changes the genus to which 

 the species must be assigned the name of the person who first gave the 

 epithet must be placed in parentheses followed by that of the author of 

 the new combination. For example, Bessey and Thompson described a 

 new species of fungus under the name Genea cuhispora Bessey & Thomp- 

 son. When Miss Gilkey determined that this belonged to the genus 

 Hydnotria, the name became Hydnotria cuhispora (Bessey & Thompson) 

 Gilkey. If the epithet was given to a plant accompanied by an adeqviate 

 description before the basic date for that group of plants it is not neces- 

 sary to refer to the author of that epithet but only to the person who 

 first used it on or after the basic date. However, this later author could 

 indicate that he took this epithet on the authority of the earlier author 

 by placing, as authority for the combination, the abbreviated name of the 

 earlier author followed by "ex" and the name of the later author. Thus 

 Persoon in 1801 described a puffball under the name Lycoperdon giganteum, 

 ascribing this combination to Batsch who published the name before 

 1790. It is permissible simply to give "Pers." as the authority, but it is 

 preferable to write "Batsch ex Pers." 



To avoid confusion a genus name once applied to any plant may not 

 ever thereafter be used for another genus, even though the name is 

 invalid for the first genus. Thus, unless an exception is made at some 

 future Botanical Congress, the generic name Empusa, given about 100 

 years ago to an orchid, is not available for a genus of the Entomophtho- 

 rales. A specific epithet once applied in a given genus may never be used 

 for another species in the same genus. 



In fungi with several stages of development to which different names 

 have been given, the species epithet that is to be retained is the one 



