Availability of new Bayesian-delimited gecko names and the importance of character-based species descriptions

Abstract

CommentAvailability of new Bayesian-delimited gecko names and the importance of character-based species descriptions Leaché & Fujita [1] present an empirical example of Bayesian species delimitation (BSD; [2]) to recognize three new species of African geckos from within the range of the widespread taxon Hemidactylus fasciatus, Gray 1842. As with any new method, BSD will undoubtedly generate questions and discussions about its practicality and assumptions. However, the use of this method of delimiting species does not obviate the need to adhere to the practice of describing or defining species on the basis of intrinsic characters.In order for any species name in zoology to be available, it must satisfy the applicable provisions of Articles 11 -20 of the International Code of Zoological Nomenclature (1999) (hereafter 'the Code'). Relevant to this issue, 'To be available, every new name published after 1930 . . . must be accompanied by a description or definition that states in words characters that are purported to differentiate the taxon (Article 13.1.1, p. 17)' where a character is 'any attribute of organisms used for recognizing, differentiating, or classifying taxa' (Glossary, p. 101). Leaché & Fujita [1] do not provide descriptions or definitions for their new taxa, only putative diagnoses (recommended but not required under the Code (Recommendation 13A)), and these are based not upon characters but upon degree of support under their species delimitation model (e.g. 'This species includes all populations that cluster with those from the Togo Hills included in this study with strong support in the Bayesian species delimitation model'). Although geographical location could be argued to be an organismal attribute, (i) Article 12.3 and, by implication, Article 13.1 [3] clarify that the mention of a locality does not in itself constitute a description, and (ii) Leaché & Fujita [1] have not actually used locality as a character, but as an indicator of the cluster to which populations belong. The new names they propose thus lack definitions or descriptions of organismal attributes (characters) as required by the Code and their diagnoses consist solely of extrinsic relational statements about populations. The new names proposed for members of the H. fasciatus group (Hemidactylus coalescens, Hemidactylus eniangii, Hemidactylus kyaboboensis) fail to conform to Article 13 and are nomina nuda, and thus unavailable under the Code.The diagnoses of their new species are similar to the definitions of clade names under phylogenetic taxonomy, but their species descriptions are also unavailable under the PhyloCode [4], which defers to 'provisions of the appropriate rank-based code (e.g. . . . ICZN)' for species availability.The unavailability of Leaché and Fujita's gecko names rests on more than a technicality. We emphasize this point to highlight the very purpose of the taxonomic protocols inherent in the Code's adherence to character-based species definitions. The application of Leaché & Fujita's approach would no doubt fac...

Out of the deep: Cryptic speciation in a Neotropical gecko (Squamata, Phyllodactylidae) revealed by species delimitation methods

“…In addition, the low assignment error (3%) of the SVM analysis shows that these lineages are morphologically distinguishable. We acknowledge that prompt descriptions of identified cryptic species are needed to avoid delays of taxonomic availability (Schlick-Steiner et al, 2007), but assessing morphological diagnostic characters is essential when proposing taxonomic revisions (Bauer et al, 2011). Because species' descriptions can be time consuming and laborious, we argue that the uncovered clades should be referred to as 'candidate species' for conservation delineation and management purposes (Bickford et al, 2007;Whittaker et al, 2005).…”

“…Coalescent-based methods have recently become popular to assist in species delimitation Fujita et al, 2012;Knowles and Carstens, 2007;Yang and Rannala, 2010), especially regarding cryptic speciation in biodiversity hotspots (Nair et al, 2012). Despite the unquestionable value of those methods in assessing cryptic diversity (Leaché and Fujita, 2010), it is advisable to use independent morphological or ecological data to corroborate molecular-based hypotheses of cryptic diversification (Bauer et al, 2011;Burbrink et al, 2011;Sistrom et al, 2012). In this context, morphological data can be used to test the placement of individuals within the reconstructed molecular clades and evaluate the validity of such lineages (Hebert et al, 2004;Sistrom et al, 2013;Tan et al, 2010).…”

Species detection and individual assignment in species delimitation: can integrative data increase efficacy?

“…Alternatively, statistical species delimitation treats species as hypotheses in a statistical framework using these objective tests to delineate evolutionarily independent lineages as species, and therefore satisfying numerous species concepts (see [12] for review). However, the sole use of genetic data in these methods has brought about questions regarding the utility of these approaches to the taxonomic description of species [13], which is the focus of ongoing debate [12][13][14]. Given the importance of distinguishing intrinsic characters, attempts have been made to ensure that approaches remain integrative in empirical studies that employ statistical species delimitation [15][16][17].…”

Lyrodus mersinensis sp. nov. (Bivalvia: Teredinidae) another cryptic species in the Lyrodus pedicellatus (Quatrefages, 1849) complex

“…In addition, the use of molecular diagnostic characters satisfies Article 13.1.1 of ICZN (1999) just as morphological characters do (Bauer et al 2011). In cryptic species, in particular, morphological characters are not an adequate proxy for species boundaries.…”