From the Shenzhen Code to the Madrid Code: New rules and recommendations for naming algae, fungi, and plants

Premise A universally understood, precise, and stable system of naming organisms is essential for effective scientific communication. The International Code of Nomenclature for algae, fungi, and plants, of which the most recently published edition is the Shenzhen Code of 2018, provides this system for algae, fungi, and plants. This Code is regularly revised at an International Botanical Congress (IBC), usually held every 6 years, most recently in Madrid, Spain, in July 2024. The Madrid IBC amended the Shenzhen Code, and the changes took effect on 27 July 2024, when the closing plenary session of the IBC approved the decisions of the Nomenclature Section. It is important to promptly publicize this information because the new edition of the Code resulting from these amendments, the Madrid Code, will not be published until mid-2025. Methods I selected some of the more important of the 433 published proposals to amend the Code at the Madrid IBC. I sourced details from the proposals themselves, the “Synopsis of Proposals” and the “Report of Congress Action” (all published in the journal Taxon) and from the records made during the Nomenclature Section in Madrid. Results For a general botanical audience, I discuss the background, outcomes (acceptance or rejection), and consequences of acceptance of the proposals. Conclusions This commentary supplements the technical reports already published and provides an overview of some of the new or amended rules and recommendations in the upcoming Madrid Code.