= Nomenclatural type
A <nomenclatural type> anchors a <taxon> name to a reference. In <prokaryotic nomenclature>, it need not be the most typical member. For a <species> this is normally a <type strain>; for a <genus (biology)> it is a designated <species>.<International Code of Nomenclature of Prokaryotes. Prokaryotic Code (2025 Revision) by Aharon Oren and others>[Rule 15 and Table 2, Taxonomic Categories and their Types]{ref}
A reference and a statistical representative need not coincide. Suppose a hypothetical group contains <bacterial strains> T, U and V, with a stipulated trait measured as 1, 10 and 11 arbitrary units. Its <arithmetic mean> is $22/3\approx7.33$ units. Designating T as the <type strain> does not require its measurement to be close to that mean. Conversely, choosing U because its value lies closer to the mean would not itself make U the designated reference.
The <nomenclatural type> also makes naming decisions interpretable when a <taxon> is divided or combined with another. It supplies an anchor for applying an existing name through a change of circumscription.<International Code of Nomenclature of Prokaryotes. Prokaryotic Code (2025 Revision) by Aharon Oren and others>[Rule 17, application after division or union]{ref}
The naming rules do not themselves delimit <taxa> or determine their biological relationships. Evidence about <genomes> and <phenotypes> supplies a different kind of information.<International Code of Nomenclature of Prokaryotes. Prokaryotic Code (2025 Revision) by Aharon Oren and others>[General Consideration 4 and Principle 1(4)]{ref}
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