Auctorum (abbreviated auct. or auctt.), in botany and zoology is a term used to indicate that a name is used in the sense of a number of subsequent authors and not in its (different) sense as established by the original author. Auctorum is Latin and means of authors.
It is often used in conjunction with nec or non to indicate a misapplied name.
It may be qualified to indicate the number of authors, e.g. auctorum multorum (abbreviated auct. mult.), Latin for of many authors, indicates that many subsequent authors used a name in a different sense to the original author.
The list of synonyms of Tinea trinotella includes Tinea tripunctella (auct. non Denis & Schiffermüller 1775). Although Tinea tripunctella seems to be listed as a synonym of Tinea trinotella, the use of auct. indicates it is in fact a valid species. In this case auct. is used in combination with non, which should be read as: as used in the sense of author(s) but not of the original author. Hence, the concept of the species as used by authors other than the original author was wrong. This wrong concept is a synonym,[clarification needed] but not the original species.
Flora Europaea gives one of the synonyms of Cistus clusii as "C. libanotis auct. mult., non L.", meaning that many authors misapplied the name Cistus libanotis to the species Cistus clusii thereby using this name differently from the original author, Carl Linnaeus.