Evidence-based review of the taxonomic status of New Zealand's endemic seed plant genera

Abstract

The nature, value and relative importance of different lines of evidence for deciding the circumscription and rank of genera are examined and discussed. First, I argue that the circumscriptions of genera (and higher taxa) should always be monophyletic, preferably with strong support from independent evidence. Second, the rank of genus is decided on more subjective grounds, but several criteria are helpful: phylogeny should be recoverable from the classification hierarchy, genera should be distinctive, ranks should not be redundant and familiar names should be retained if other criteria are met. I then apply these criteria to an evaluation of the circumscription and rank of 59 New Zealand endemic genera of seed plants accepted in two recent checklists. Fifteen genera (25.4%) were rejected and 16 (27.1%) are considered equivocal. However, my lower estimate almost certainly underestimates endemism at genus rank because the circumscriptions of several genera not evaluated here, such as Pachycladon, could change in the future to become endemic. One new combination is made: Sonchus novae-zelandiae (Hook.f.) Garn.-Jones, although work in progress by others is likely to lead to several more. © 2014 The Royal Society of New Zealand.