Should universal guidelines be applied to taxonomic research?

In an attempt to facilitate the integration of various methods of species delimitation, Dayrat (2005) recommends a set of nomenclatorial guidelines. He proposes to restrict the application of new specific epithets where a recent taxonomic revision has not dealt with the totality of names and variation in the group, where specimens are not well-represented in collections, where DNA extraction from type specimens is not possible, and where putative novel species are supported only by a single type of data (e.g. morphological). Dayrat further recommends that putative novel species for which only one type of data exists be described with the abbreviation 'sp.', so as to avoid the permanent establishment of a specific epithet, as required by the current codes of nomenclature. Contradicting himself, Dayrat implies that putative novel species supported only by DNA sequences should be named as valid species. If adopted, Dayrat's guidelines would impede taxonomic progress, diminish the utility of taxonomy to its users (e.g. conservation biologists and biogeographers), and prevent the integration of methods of species delimitation. (c) 2007 The Linnean Society of London.