= Subspecies
A <subspecies> is a named <taxon> at a <taxonomic rank> below <species>. It distinguishes a subdivision within a species under a stated classification. The rank does not itself specify one universal percentage of sequence similarity, degree of <reproductive isolation> or age of divergence.<International Code of Nomenclature of Prokaryotes. Prokaryotic Code (2025 Revision) by Aharon Oren and others>[Rules5a–5b: order of taxonomic categories and variability of their definitions]{ref}
A concrete naming convention comes from <prokaryotic nomenclature>. The Code forms a subspecies name from the genus name, specific epithet, abbreviation `subsp.` and subspecific epithet. It separately states that a subspecies containing the species' type bears the same epithet as the species. Naming conventions and the biological evidence used to recognize a subdivision are different matters.<International Code of Nomenclature of Prokaryotes. Prokaryotic Code (2025 Revision) by Aharon Oren and others>[Rules13a and13d, printed p.10: ternary names and the type-containing subspecies]{ref}
An original hypothetical example uses genus labelG, species epithetb and a proposed second subgroup epithetc. The name pattern is `G b subsp. c`; the type-containing subgroup has the pattern `G b subsp. b`. These are placeholders illustrating the rule, not asserted validly published taxon names.
A second example separates a rank from a measurement. Suppose two sampled populations have trait means10 and12 units but overlapping ranges. The means alone do not determine whether they should be named as subspecies, treated as variation within an undivided species or recognized differently using additional evidence. Sampling, inherited differences and the chosen taxonomic framework still need to be examined.
A <strain (biology)> and a <subspecies> also supply different kinds of reference. Many independently maintained strains can be placed within one subspecies; culture accession numbers do not create additional taxonomic ranks. The <type strain> anchors the relevant name under the prokaryotic rules, while experiments determine properties of the actual material.<International Code of Nomenclature of Prokaryotes. Prokaryotic Code (2025 Revision) by Aharon Oren and others>[Rules15 and18a: nomenclatural types of species/subspecies; Appendix10A(3): strain terminology]{ref}
The applicable nomenclatural code should accompany a precise naming claim. The prokaryotic example explains one system's rules; it does not impose every one of those conventions on all other groups of organisms.
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