Article 56. Genus-group names.
56.1. Application of the Principle of Homonymy. The Principle of Homonymy applies to all genus-group names, including names of collective groups and of ichnotaxa at the genus-group level [Arts. 1.2, 23.7, 42.2].
56.2. One-letter difference. Even if the difference between two genus-group names is only one letter, they are not homonyms.
Example. Two generic names in Diptera, Microchaetina van der Wulp, 1891 and Microchaetona Townsend, 1919, are not homonyms.
56.3. Precedence of genus over subgenus. Of two homonymous genus-group names of identical date, one established for a genus and the other for a subgenus, the former takes precedence over the other [Art. 24.1].