485Dayrat & al. • A new species nomenclature 53 (2) • May 2004: 485–491The PhyloCode (Cantino & de Queiroz, 2003),which intends to replace the current international codesof nomenclature (bacterial, botanical, and zoological; orICNBa, ICBN, ICZN), is a rank-free system in which tra-ditional Linnaean categories such as genus, family, ororder are abandoned. It is important to note that the cur-rent version of the PhyloCode is a rank-free code ofnomenclature only, and not a set of rules for rank-freeclassification (although we are in favor of both rank-freenomenclature and classification to avoid any confusionconcerning ranks). Only two types of taxa exist under thePhyloCode, species and clades, and the terms“species”and “clade” refer to “different kinds of biologi-cal entities, not ranks” (Note 3.1.1; most recent revisionDecember 21, 2003). Because the PhyloCode governsonly the naming of organisms, and not classification,species names should not convey information (or misin-formation) about supra-specific classification. However,the current binominal species nomenclature, which isbased on a combination of a generic name and a specificepithet, by its very nature conveys information aboutsupra-specific classification. Therefore, it is not compat-ible with the independence of names and classificationproposed in the PhyloCode. Furthermore, the use ofbinominal species names also is not compatible with theabsence of a mandatory genus rank under the PhyloCode(Cantino & al., 1999). These issues are especially prob-lematic because the current draft of the PhyloCode onlygoverns clade names; it does not deal with speciesnames. We are promised (p. 3) that “rules governingspecies names will be added in the future”, but an officialschedule is not provided.We assert that the PhyloCode should not be imple-mented if no method for naming species is proposed(currently, this implementation is scheduled to occurwith the publication of the symposium volume based onthe First International Phylogenetic NomenclatureMeeting, which will be held in July, 2004, Paris).Otherwise, we may face the paradoxical situation wherethe PhyloCode would oblige systematists to continueusing the current rank-based codes for species names.There are two main classes of possible methods fornaming species in the PhyloCode: those that maintain abinominal form, and those that are epithet-based. For thereasons mentioned above (i.e., distinction betweennames and classification, and the absence of a mandato-ry genus rank, and thus generic names), we reject thebinomial-based methods that have been proposed for usewith the PhyloCode. The potential for confusion is par-ticularly striking in the case of the creation of newspecies names. Therefore, we argue that the solution isfor species names to become epithet-based. A problemthat must be solved in this context is how to guaranteethe uniqueness of epithet-based species names, consider-ing that many species share the same epithet.We present an epithet-based form of species namethat is fully compatible with the rank-free system of thePhylocode, in which the genus rank does not exist. Also,it guarantees uniqueness in all situations. However, wedo not intend to argue that species names under thePhyloCode must follow the method we describe,although we find it convenient. Instead, we wish to stim-ulate a needed debate on the form of species names in arank-free system.The absence of rules for species names inthe PhyloCode. —A discussion of species nomencla-ture is conspicuous in its absence from the current draftof the PhyloCode. Several issues could account for thedelay in proposing a form for species names. For exam-ple, there is disagreement on whether or not speciesshould be considered “biological entities” distinct fromclades, and several authors have suggested that the statusof species as a special biological “entity” be abandonedin Phylogenetic Nomenclature (e.g., Mishler, 1999;Pleijel, 1999). However, the form of “species” names isindependent of one’s opinion on the distinction ofspecies and clades, and consensus must be reached on therules for naming the least-inclusive taxa, regardless ofwhether they are “species”, “least-inclusive clades”, or“fundamental units”. A related debate concerns how “species” namesshould be defined (e.g., Lee, 2002). This question is ofprimary importance because it will determine if “spe-cies” names will be based on type specimens (as in thecurrent codes) or by means of phylogenetic definitions(similar to clades in the PhyloCode). Moreover, it isrelated to broader issues, such as the applicability of phy-logenetic methods at the intra-specific level, whereSuggestions for a new species nomenclatureBenoît Dayrat1, Christoffer Schander2& Kenneth D. Angielczyk11California Academy of Sciences, Golden Gate Park, San Francisco, California 94118, U.S.A. [email protected] (author for correspondence)2University of Bergen, Department of Biology, Postbox 7800, NO-5020 Bergen, Norway.(according to the Hennigian framework) relationshipsare tokogenetic, not phylogenetic. Finally, no method for naming species that agreeswith the rank-free PhyloCode has been agreed upon,although several possibilities have been described(Cantino & al., 1999).Our goal is not to discuss the conceptual issues sur-rounding the nature of “species”, but rather to address theform that species names should follow in the PhyloCode.This must be dealt with regardless of whether species arequalitatively different than higher clades, or if phyloge-netic definitions should be provided when establishingspecies names. Furthermore, a convincing form ofspecies name is critical to impel taxonomists and users oftaxon names to adopt the PhyloCode.On uniqueness, homonymy, synonymy. — Inthe current codes, uniqueness applies to all so-called“legitimate” (ICBN, ICNBa) or “available” (ICZN)names. All of the current codes prohibit homonymy (bothprimary and secondary), and this framework guaranteesthat a particular combination of a genus name andspecies epithet is unique. In the context of the currentcodes, the uniqueness of names is a nomenclatural issuethat should not be confused with the notion of “correct”(ICBN, ICNBa) or “valid” (ICZN) names. A valid (or cor-rect) name is the name selected among all the available(or legitimate) names that refer to the same taxon. Theselection of valid (or correct) names is regulated by a
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