What to do with Hibiscus? A proposed nomenclatural resolution for a large and well known genus of Malvaceae and comments on paraphylyB. E. Pfeil A B C and M. D. Crisp A
A Australian National University, School of Botany and Zoology, Canberra, ACT 0200, Australia.
B CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia.
C Present address: 228 Plant Science Bld, Cornell University, Ithaca NY 14853, USA. Corresponding author. Email: email@example.com
Australian Systematic Botany 18(1) 49-60 https://doi.org/10.1071/SB04024
Submitted: 16 July 2004 Accepted: 24 January 2005 Published: 29 March 2005
The generic classification of Hibisceae has long been unstable. A new understanding of the phylogeny of Hibisceae has found that genera from three tribes (Decaschistieae, Hibisceae and Malvavisceae) are nested within Hibiscus. We discuss issues that impinge upon the classification of Hibiscus in a general sense, including the genus concept, monophyletic and paraphyletic taxa, the use of characters and phylogenies to define taxa, and the current ranked system (based on the International Code of Botanical Nomenclature) v. a rank free alternative (the PhyloCode). We conclude that genera are subjective constructs that are only real in the sense of their phylogenetic origins (i.e. the taxa they denote may be real discoverable monophyletic groups), that paraphyletic taxa are not necessary in classification, that overemphasis of ‘distinctive’ characters in preference to phylogenies leads to recognition of paraphyletic taxa, and that there is no objective fixed and discoverable rank for any taxon. While the PhyloCode avoids some of these problems, it fails to adequately provide an alternative to the mnemonically powerful and information rich Linnean binomial and its advantages do not, in our opinion, outweigh the utility of the ICBN system when the latter employs only monophyletic taxa. With these conclusions in mind, we offer a brief set of guidelines for higher level classification and apply this to Hibiscus. The severe paraphyly in Hibiscus means that no classification using the ICBN system with exclusively monophyletic taxa will be free of major nomenclatural changes. We argue that including over 200 species from several genera within a broadly defined Hibiscus causes fewer nomenclatural changes overall than do alternative schemes, while promoting stability and attempting to minimise change to well known species. A hybrid formal ranked and informal rank free system is discussed and proposed for this group. A series of rank free names that are nested within Hibiscus s.l. are proposed to convey information about membership of distinctive clades within Hibiscus s.l. in lieu of a complete ranked subgeneric classification that awaits more investigation.
BEP thanks Curt Brubaker and Lyn Craven for their excellent and generous supervision during his PhD study as well as for helpful comments on an early draft of this paper. We thank David Baum for many helpful comments on final drafts, and he and Maggie Koopman for access to unpublished ndhF and matK results. BEP was supported by an APA (1999–2002); other funding from ABRS and CSIRO was also invaluable during this time and is gratefully acknowledged. Two anonymous reviews helped improve the manuscript.
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