Formation of names of genera of prokaryotes that end on -oides or -opsis. A proposal for addenda to Rule 65(2) and Appendix 9 of the International Code of Nomenclature of Prokaryotes.

In view of the current confusion about the correct gender of genus names ending on -oides, and possible confusion in the future for genus names ending on -opsis, we propose non-retroactive addenda to Rule 65(2) and Appendix 9 of the International Code of Nomenclature of Prokaryotes so that new genera to be formed by adding the ending -oides to the stem of an existing genus name or another (Neo-) Latin word must be treated as neuter and genus names ending on -opsis are to be treated as feminine.