Are the linnean and phylogenetic nomenclatural systems combinable? Recommendations for biological nomenclature.

A combination approach between the rules and recommendations from the Linnean (rank-based) and phylogenetic nomenclature is proposed, with a review of the debate. Advantages and drawbacks of both systems are discussed. Too often the debates are biased and unconstructive, and there is a need for dialogue and compromise. Our recommendations for the future of biological classification, to be considered by new editions of all codes of nomenclature, would enable the Linnean and the phylogenetic nomenclatural systems to coexist, or be combined. (1) We see it as essential that species binomen, including the formal rank of genus, are retained, and (2) species should continue to be linked to type specimens. (3) The use of other formal ranks should be minimized; however, we suggest retaining the classical supergeneric ranks (family, class, order, phylum, kingdom) for purely practical reasons. (4) For these ranks and any formally defined clades, type taxa (species, genera) should be replaced by phylogenetic definitions that explicitly hypothesize monophyly. (5) In contrast, species monophyly should not be required, because theory predicts that many species are not monophyletic. (6) It should be stressed that equal ranks do not imply comparable evolutionary histories.