Bacteria and Viruses 49 



Recommendation 8a. Sect. 1. Naming of Taxo 



RECOMMENDATION 8a (2). Type is a term which has frequently been used 

 to designate a subdivision of a soecies, particularly in cases where the 

 distinguishing characters are regarded as insufficient to justify the recog- 

 nition of a subspecies. Types are often distinguished on the basis of anti- 

 genic characters. However, in view of the preferred use of the word "type" 

 in a different sense as defined in Principle 1 1 and Rule 9, it is recommended 

 that the terms serotype (or serological type), biotype (or physiological type), 

 phagotype (or phage type) and morphotype (or morphological type) be ap- 

 propriately substituted for type as a designation of a subdivision of a species. 



ANNOTATIONS 



Recojnmendation 8a (2) . The continued use of the word "type" in 

 microbiology with two very different meanings is a major source of 

 confusion. The preferable and recommended use of "type" is that 

 in the sense of "nomenclatural type" of a taxon and in phrases such 

 as "type culture" and "type species", as noted in Principle 11 and par- 

 ticularly Rule 9. This use of the word "type" is recommended. 



The second common and less desirable use of the word "type" 

 is for the designation of certain strains or cultures or groups of these 

 within a species which show certain distinctive characters of less than 

 subspecific rank. Certain substitute terms are recommended. 



A "serotype" is a subdivision (infrasubspecific) of a species or 

 subspecies distinguishable from other strains of the same species on 

 the basis of its antigenic structure. It may be suitably named by 

 use of the species name followed by '"serotype" and this in turn bv 

 a suitable epithet or formula, as, for example. SItigella flexneri sero- 

 type la. 



A "biotype" is a subdivision of a species, subspecies or serotype 

 which may be distinguished from other subdivisions of the species 

 by possession of some special or usefully diagnostic physiological 

 character. An anaerogenic mutant of an aerogenic species of bacteria 

 might be named by following the species name by "biotype anaero- 

 genes" (or, anaerogenic biotype) . 



A "morphotype" is a subdivision of a species distinguished by 

 possession of some special or unusual morphological character which 

 may or may not be associated with a change in serological state. A 

 capsulated variant of a bacterial species in which the cells are 

 normally noncapsulated might be named by use of the species name 

 followed by "'morphotype capsiilatus." 



A "phagotype" is a subdivision of a species which is distinguished 

 by its sensitivity to a particular bacteriophage or by a distinctive 

 pattern of sensitivity to a set of specific bacteriophages. It may be 

 characterized by the carriage of a symbiotic phage. 



