Phylogeny of the Manta and Devilrays (Chondrichthyes: Mobulidae), with an Updated Taxonomic Arrangement for the Family

Phylogeny of the Manta and Devilrays (Chondrichthyes: Mobulidae), with an Updated Taxonomic Arrangement for the Family

Zoological Journal of the Linnean Society, 2017, XX, 1–26. With 8 figures. Phylogeny of the manta and devilrays (Chondrichthyes: Mobulidae), with an updated taxonomic arrangement for the family WILLIAM T. WHITE1,2*, SHANNON CORRIGAN3, LEI YANG3, AARON C. HENDERSON4, ADAM L. BAZINET5, DAVID L. SWOFFORD6 and GAVIN J. P. NAYLOR3,7 1CSIRO National Research Collections Australia – Australian National Fish Collection, Hobart, TAS 7000, Australia 2CSIRO Oceans & Atmosphere, Hobart, TAS 7000, Australia 3Department of Biology, College of Charleston, Charleston, SC 29401, USA 4Department of Natural Sciences, School of Science and Computing, Galway-Mayo Institute of Technology, Dublin Road, Galway H91 T8NW, Ireland 5Laboratory of Molecular Evolution, Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD 20742, USA 6Department of Biology, Duke University, Durham, NC 27708, USA 7Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA Received 6 April 2016; revised 30 January 2017; accepted for publication 19 March 2017 DNA sequence data from mitochondrial genomes and c. 1000 nuclear exons were analysed for a complete taxon sampling of manta and devilrays (Mobulidae) to estimate a current molecular phylogeny for the family. The result- ing inferences were combined with morphological information to adopt an integrated approach to resolving the taxonomic arrangement of the family. The members of the genus Manta were found to consistently nest within the Mobula species and consequently the genus Manta is placed into the synonymy of Mobula. Mobula eregoodootenkee, M. japanica and M. rochebrunei were each found to be junior synonyms of M. kuhlii, M. mobular and M. hypostoma, respectively. The mitochondrial and nuclear tree topologies were in agreement except for the placement of M. tara- pacana which was basal to all other mobulids in the nuclear exon analysis, but as the sister group to the M. alfredi– M. birostris–M. mobular clade in the mitochondrial genome analysis. Results from this study are used to a revise the taxonomy for the family Mobulidae. A single genus is now recognized (where there were previously two) and eight nominal species (where there were previously 11). ADDITIONAL KEYWORDS: DNA hybridization capture – Manta – Mobula – phylogenetics – taxonomy. INTRODUCTION of available biological and ecological data for members of the Mobulidae revealed large gaps for many param- The manta and devilrays of the family Mobulidae con- eters. In fact, the majority of studies investigating the stitute some of the most charismatic species of rays. biology and ecology of mobulid rays have focused on They are large (up to 7 m disc width), planktivorous particular species in specific locations, limiting our species, occurring worldwide in tropical and temper- ability to make generalizations at higher taxonomic ate waters (Last & Stevens, 2009). Despite the pub- levels. Very few broad regional or global studies of lic attention they receive, there is still uncertainty mobulid ray biology and ecology have been undertaken. regarding their taxonomy, phylogeny, life history Taxonomic research on this group has been compli- and population structure. This was highlighted by cated by poor representation of mobulids in biological Couturier et al. (2012), whose comprehensive review collections because of their large size. Notarbartolo di Sciara (1987) provided a comprehensive revision of *Corresponding author. E-mail: [email protected] the genus Mobula, including a description of a new © 2017 The Linnean Society of London, Zoological Journal of the Linnean Society, 2017, XX, 1–26 1 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected] 2 W. T. WHITE ET AL. species. That study represented a major step forward mobulids, or have focused on the evolution of particu- in our understanding of mobulid taxonomy. Marshall, lar structures. Making taxonomic decisions based on Compagno & Bennett (2009) revised the genus Manta, these works has thus largely been limited by incom- resurrecting a second species, M. alfredi (Krefft, 1868), plete taxon sampling. as well as acknowledging a third putative species. Molecular phylogenetic inferences have considered a Most recently, Notarbartolo di Sciara et al. (2016) pro- more complete taxon sampling and provided interesting vided a redescription of the poorly known Mobula kuh- insights regarding the evolutionary history of Mobulidae. lii (Müller & Henle, 1841). However, these have been exclusively based on the mito- The Mobulidae currently comprises two genera, chondrial genome (Aschliman, 2011; Naylor et al., 2012b; Manta and Mobula. The genus Manta encompasses Poortvliet et al., 2015). Two recent estimates of mobulid two nominal species, the reef manta M. alfredi (Krefft, phylogeny were based on data collected from both the 1868) and the giant manta M. birostris (Walbaum, 1792), mitochondrial and nuclear genomes; however, only a and possibly a third species (M. sp. cf. birostris sensu small number of nuclear markers were assessed and the Marshall et al., 2009). There are nine currently recog- data lacked resolution (Aschliman, 2014; Poortvliet et al., nized species in the genus Mobula: the pygmy devilray 2015). This is problematic, especially for the purposes of M. eregoodootenkee (Bleeker, 1959), the Atlantic devilray distinguishing species boundaries and making taxonomic M. hypostoma (Bancroft, 1831), the spinetail devilray decisions among closely related lineages. Coalescent M. japanica (Müller & Henle, 1841), the shortfin devilray variation and the potential for gene tree–species tree M. kuhlii, the giant devilray M. mobular (Bonnaterre, discordance (Maddison, 1997) are now well-documented 1788), Munk’s devilray M. munkiana Notarbartolo di and estimating phylogenies based on a small number Sciara, 1987, the lesser Guinean devilray M. rochebru- of molecular markers is now considered insufficient for nei (Vaillant, 1879), the Chilean devilray M. tarapacana these purposes. Moreover, many factors and processes (Philippi, 1892), and the bentfin devilray M. thurstoni can lead to differential phylogenetic signal between the (Lloyd, 1908). Previous studies of mobulid phylogeny, mitochondrial and nuclear genomes. These include lin- based on both morphological (Adnet et al., 2012; Paig- eage sorting, demographic asymmetries, selection and Tran et al., 2013) and molecular data (Aschliman, 2011, hybridization. Although taxonomic uncertainties have 2014; Naylor et al., 2012b; Poortvliet et al., 2015) indi- been discussed, all authors have favoured taxonomic sta- cate that the family is a monophyletic lineage compris- bility for the group in light of their various limitations. ing three clades. One clade includes the larger mobulid There is considerable concern regarding the con- species Manta spp., M. tarapacana, M. ­mobular and servation status of mobulid rays globally, evidenced M. japanica. The remaining two clades comprise by the inclusion of Manta spp. in Appendix II of the the smaller species M. kuhlii–M. eregoodootenkee– Convention on International Trade in Endangered M. thurstoni and M. munkiana–M. rochebrunei– Species of Wild Fauna and Flora (CITES) in 2013 M. hypostoma. (CoP16). It is argued that Mobula spp. are subject to Despite this progress in characterizing mobulid much higher levels of exploitation than Manta spp. in diversity, mobulid taxonomy overall remains largely some regions (e.g. Indonesia; White et al., 2006) and unresolved due to a very complicated nomenclatural these too were listed on CITES Appendix II in 2016 history and the fact that phylogenetic inferences have (CoP17). Further research that can inform the conser- been limited by gaps in taxonomic and/or genomic vation management of these species is thus urgently sampling. Notable long-standing uncertainties regard- required. Taxonomy is recognized as the founda- ing mobulid taxonomy include the validity of the tion that underpins our knowledge of biodiversity genus Manta (Herman et al., 2000; Adnet et al., 2012; (Simpfendorfer et al., 2011). From a conservation man- Paig-Tran et al., 2013; Naylor et al., 2012b; Aschliman, agement perspective, it is crucially important to accu- 2014; Poortvliet et al., 2015), as well as distinguish- rately recognize the biodiversity within vulnerable ing species boundaries from intraspecific geographi- groups, such as the mobulids, so that conservation pri- cal variants within multiple lineages of Mobula. orities may be identified and management strategies Specifically, gross morphological and/or genetic devised that are both efficient and effective. The most similarities have been noted between species pairs robust approach to identifying taxonomic boundaries M. kuhlii/M. eregoodootenkee, M. hypostoma/M. roche- is to assess multiple data types from a large number brunei and M. mobular/M. japanica that suggest of comparative samples. However, when considering they may possibly be conspecifics (Notarbartolo di rare and endangered animals, this becomes imprac- Sciara, 1987; Paig-Tran et al., 2013; Poortvliet et al., tical and employing the precautionary principle may 2015; Henderson et al., 2016). Phylogenetic inferences mean making taxonomic

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