Article 39. Invalidity due to homonymy or suppression of the name of the type genus. The name of a family-group taxon is invalid if the name of its type genus is a junior homonym or has been totally or partially suppressed (see Articles 81.2.1 and 81.2.2) by the Commission. If that family-group name is in use it must be replaced either by the next oldest available name from among its synonyms [Art. 23.3.5], including the names of its subordinate family-group taxa, or, if there is no such synonym, by a new name based on the valid name (whether a synonym or a new replacement name (nomen novum)) of the former type genus.

Example. In the Collembola the family name DEGEERIIDAE Lubbock, 1873 was based on Degeeria Nicolet, 1842, a junior homonym of Degeeria Meigen, 1838 in Diptera. DEGEERIIDAE had no synonyms and a new name (nom. nov.) ENTOMOBRYIDAE Tömösváry, 1882 was based upon Entomobrya Rondani, 1861, a new replacement name (nomen novum) for Degeeria Nicolet.