INTERNATIONAL JOURNAL OF SYSTEMATIC BACTERIOLOGY Vol. 16, No. 4 October 1966 pp. 459-490 INTERNATIONAL CODE OF NOMENCLATURE OF BACTERIA^ Edited by The Editorial Board of the Judicial Commission of the International Committee on Nomenclature of Bacteria Approved by The Judicial Commission of the International Committee on Nomenclature of Bacteria The Internjti.ona1-Committee on Nomenclature of Bacteria The Ink rnational Association of Microbiological Societies The IX International Congress of Microbiology, Moscow, USSR (1966) Chapter 1 GENERAL CONSIDERATIONS -1. -1. The progress of bacteriology can be furthered by a precise system of nomenclature which is properly integrated with the systems used by botanists,, zoologists and virologists, and accepted by the majority of bacteriologists in all nations. The International Code of Nomenclature of Bacteria applies to bacteria and related organisms. Botanical and zoological codes now provide, and a virological code when approved will provide, for the nomenclature of certain other microbial groups such as fungi, algae, protozoa and viruses. General Consideration 2. The precepts on which this system of nomen- clature of bacteria is based are divided into Principles, Rules, and Re- commendations . Principles (Chapter 2) formthe basis of the rules and recommenda- tions. Rules (Chapter 3) are designed (a) to make effective the Principles given in Chapter 2. (b) to put the nomenclature of the past in order, and (c) to provide for the nomenclature of the future. The rules in general are retroactive; names or forms of nomenclature contrary to a rule (illegitimate names or forms) cannot be maintained. Certain &s authorize appendices and define their scope and author- ity. The rules of nomenclature do not govern the delimitation of taxa nor determine their interrelationships. They do not limit taxonomic freedom in classification. They primarily assess the correctness of names applied to defined taxa. Reprints of this 1966 English edition of the International Code of Nomenclature of Bacteria (with covers) may be purchased from the International Microbiological Fund, 22 1 Science Hall, Iowa State University, Ames, Iowa 50010 U.S.A. Price: $1.00 460 INTERNATIONAL JOURNAL Recommendations deal with subsidiary points, their object being to bring about greater uniformity and clearness, especially in future nomencla- ture; names or forms contrary to a recommendation cannot on that account be rejected, but they are meant to prevent a repetition of unde- sirable procedures of the past. Recommendations are appended to the rules which they supplement. Notes attached to rules or recommenda- tions are intended to be explanatory or illustrative and have the same force as the rules or recommendations to which they are appended. General Consideration 3. Provisions (Chapter 4) for emendations of rules, for special exceptions to rules, and for their interpretation in doubtful cases have been made through the establishment of an Inter- national Committee on Nomenclature of Bacteria for the International Sssociation of Microbiological Societies and of its Judicial Commission. Chapter 2 PRINCIPLES m.The essential points in nomenclature are: (1) to aim at fixity of names; (2) to avoid or to reject the use of names which may cause error or ambiguity or throw science into confusion. Next in importance is the avoidance of all useless creation of names. Other considerations, such as absolute grammatical correctness, regu- larity, or euphony of names, more or less prevailing custom, regardfor persons, etc. , notwithstanding their undeniable importance, are relative- ly accessory. -. -. In the absence of a relevant rule, or where the consequences of a rule are doubtful, established custom must be followed. In case of doubt a re'sume' in which all pertinent facts are outlined should be sub- mitted to the Judicial Commission for an Opinion. m.Nomenclature of bacteria and the nomenclature of algae and fungi, of protozoa, and of viruses, are interdependent in the sense that the name of a bacterial taxon is to be rejected if it is a later homonym of a name of a taxon of algae, fungi, protozoa or viruses. Nomenclature of bacteria is independent of botanical nomenclature (algae and fungi excep- ted) and of zoological nomenclature (protozoa excepted). m.Scientific names of all taxa are usually taken from Latin or Greek. When taken from any language other than Latiq or formed in an arbitrary manner, they are treated as if they were Latin. Latin termi- nations should be used as far as possible for new names. The classic Latin rules for latinization of Greek and other words of non-Latin origin should be followed. wu. Nomenclature deals with : (1) the terms which denote the categories of taxa, such as species, genus, family and the relative ranks of these categories. (2) the names which are applied to individual taxa, such as Bacillus subtilis, Streptococcus, Spirillaceae, Spirochaetales. SYSTEMATIC BACTERIOLOGY 461 Not< 1. The use nf the word taxon (plural =a) is appropriate for the term taxonomic group or the word group wherever used in the sense of taxommic group in this Code. The word group has as its preferred use in bacteriology that indicated in Recommendation 8a/7). Note 2. The word name unless otherwise indicated, means a name which has been validly published, whether legitimate or illegitimate. A legitimate name or epithet is one that is in accordance with the rules. An illegitimate name or epithet is one that is contrary to the rules. The correct name of a taxon with a particular dircumscription, position, and rank is the name which must be adopted for it under the rules. A name is effectively published when its publication is in accordance with Rule 11. A name is validly published when its publication is in accordance with Rules 12, 13 and 14. -. -. The rules and recommendations of bacteriological nomen- clature apply to all bacteria, recent and fossil, with certain distinctly specified exceptions. m.The terms which denote the rank of taxa are defined as follows : (a) Every individual is treated as belonging to a number of categories of consecutive rank and consecutively subordinate: of these the species is the basic one. The principal categories in ascending sequence are species (species), genus (genus), family (familia), order (ordo), class (classis), division (divisio). In some genera the rank subgenus (sub- genus) may be distinguished, and in some families the rank tribe (tribus). (b) In some genera, in descending sequence, there are recognized sections, subsections, series, and subseries. These taxa are placed between subgenus and species. (c) In many species, subspecies or varieties are distinguished; in some cases infrasubspecific subdivisions of .a species such as formae speciales, serotypes, variants, and others may be recognized. (d) If a greater number of intermediate categories (ranks) are required, the terms for these subdivisions are made by adding the prefix 'lsub-" to the terms denoting the ranks. Thus, subfamily denotes a rank between a family and a tribe, subtribe a rank between a tribe and a genus, etc. (e) The definition of each of these categories (ranks) varies, up to a certain point, according to individual opinion and the state of the science; but their relative order, sanctioned by custom, must not be altered. No classification is admissible which contains such alterations. -Note. A summary of the names of the categories of taxa that may be recognized in the Bacteriological Code is given below. Those names that should be recognized where pertinent in taxonomy of bacteria are printed in bold-face type. Those which are optional are printed in Roman. The equivalent Latin is given in parentheses. 1. bn(divisio) ~ 5. mr(Ordo) ~ 2. Subdivision (subdivisio) 6. Suborder (Subordo) 3. (Classis) 7. m(Familia) 4. ms(Subclassis) 8. -(Subfamilia) 462 INTERNATIONAL JOURNAL 9. m(Tribus) 15. Series (Series) 10. Subtribe LSubtribus) 16. Subseries (Subseries) 11. ws[Genus) 17. ws(Species) 12. Subgenus (Subgenus) 18. Subspecies (Subspecies) 13. Section (Sectio) Variety (Varietas ) 14. Subsection (Subsectio) 19. -1 (Individuum) m.The primary purpose of giving a name to a taxon is not to indicate the characters or the history of the name of the taxon but to supply a means of referring to it. -. -. Each order or taxon of lower rank with a given circum- scription, position and rank can bear only one correct name, the earliest that is in accordance with this Code of Nomenclature. Provision is made for exceptions that have been approved for inclusion in the list of nomina conservanda. In subgenera, genera, and taxa of higher rank to order inclusive, the correct name is the earliest name published, provided it is in conformity with the rules of this Code. In species the correct name is the binary and in subspecies the ternary combination of the generic name with the earliest available legitimate epithet validly published with the same rank m.Bacteriologists are urged not to change the name of a taxon without serious motives, based either on more profound knowledge of facts or on the necessity of giving up a nomenclature that is contrary to the Rules of this Code. m.The application of the names of taxa is determined by means of nomenclatural types (nominifers). A nomenclatural type is that constituent element of a taxon to which the name of the taxon is perma- nently attached, whether as the accepted name or as a synonym. -Note. The phrase “constituent element of a taxon” for a species or a subspecies of bacteria is the type specimen, usually a type strain or culture. m.A name of a taxon has no status under the Rules and no claim to recognition by bacteriologists unless it is validly published. Chapter 3 RULES OF NOMENCLATURE WITH RECOMMENDATIONS Section 1 Naming of Taxa of Various Ranks Rule 1. The name of each taxon above the rank of genus is a substantive Mrvwc or an adjective used as a substantive, of Greek or Latin origin, or a latinized word, in the feminine gender and in the plural number.