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Taxonomic reassessment and redescription of Okenia polycerelloides (Ortea & Bouchet, 1983) (Nudibranchia: Goniodorididae) based on morphological and molecular data

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Okenia polycerelloides (Ortea & Bouchet, 1983) is a small goniodoridid nudibranch originally described from the Canary Islands. Its taxonomic history has been problematic since its original description, a situation that worsened after this taxon was synonymized with Okenia zoobotryon (Smallwood, 1910), one of the most problematic Okenia Menke, 1830 species. Because of their external similarity, it has been difficult to determine the differences between the two taxa without a meticulous anatomical study. Thus, we present herein the first complete anatomical study of O. polycerelloides, based on specimens from the type locality and from Brazil (the latter previously identified as O. zoobotryon). A topotype of O. zoobotryon was also analyzed. Additionally, we also performed a preliminary molecular analysis on these species. Okenia polycerelloides can be distinguished externally from O. zoobotryon by the absence of integumentary spicules and the presence of a posterodorsal papilla, and internally by characteristics of the digestive (shape of the salivary glands, length of the typhlosole) and reproductive systems (diameter and length of the penial sac; cilia on the penis; and shapes of the seminal receptacle, bursa copulatrix, and ampulla). Molecular analysis revealed a high genetic divergence in both COI and H3 genes between O. polycerelloides and O. zoobotryon, which support both species as distinct. Therefore, we present a redescription and propose to restore the species status of O. polycerelloides, and consider the records of O. zoobotryon in the South Atlantic Ocean as attributable to O. polycerelloides, until new evidence may suggest otherwise.

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We are grateful to Elizabeth Kools and Terry Gosliner for the loan of specimens held by the California Academy of Sciences (CASIZ), and to Leopoldo Moro Abad and Manuel Caballer Gutiérrez (Manuel Caballer MNHN, project E-RECOLNAT: ANR-11-INBS-0004) for the donation of the topotype and images of the holotype. We thank Philippe Bouchet and Virginie Héros for the opportunity to analyze the type material of O. polycerelloides deposited in the MNHN and again to Manuel Caballer Gutiérrez for the support during the visit to the collection. We also thank the Universidade de São Paulo (USP), particularly the staffs of the laboratories of electron microscopy of the Museu de Zoologia (MZSP) and the Instituto de Biociências (IB-USP), for their help in the SEM preparations, and of the Centro de Biologia Marinha for their assistance in the laboratory and field work during this study (CEBIMar-USP; project no. 810).


This study was supported by fellowships from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES – Finance Code 001) and the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) to LS (grant 2013/08425-0). Partial funding was also provided by FAPESP to CMC (grant 2010/11253-9) and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) to AEM (grant 308056/2015-9). This paper is a contribution of NP-BioMar, USP.

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Correspondence to Licia Sales.

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All necessary permits for sampling and observational field studies have been obtained by the authors from the competent authorities and are mentioned in the acknowledgements, if applicable.

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The datasets generated and/or analyzed during the current study are available in the GenBank (National Institutes of Health genetic sequence database) repository, https://www.ncbi.nlm.nih.gov/genbank/.

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Sales, L., Migotto, A.E., Baroni, S. et al. Taxonomic reassessment and redescription of Okenia polycerelloides (Ortea & Bouchet, 1983) (Nudibranchia: Goniodorididae) based on morphological and molecular data. Mar Biodiv 49, 2351–2368 (2019). https://doi.org/10.1007/s12526-019-00972-w

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  • Bermudella
  • Okenia zoobotryon
  • Anatomy
  • Taxonomy
  • Re-instatement
  • Amathia verticillata