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ESR 53:67-87 (2024)  -  DOI:

Review of three southwestern Indian Ocean species of Rhinobatos (Rhinopristiformes: Rhinobatidae)

Rachel M. Aitchison1,*, David A. Ebert1,2,3, Bernard Séret4, Simon Weigmann5,6

1Pacific Shark Research Center, Moss Landing Marine Laboratories, San Jose State University, Moss Landing, CA 95039, USA
2Research Associate, Department of Ichthyology, California Academy of Sciences, San Francisco, CA 94118, USA
3Research Associate, South African Institute for Aquatic Biodiversity, Grahamstown 6140, South Africa
4IchtyoConsult, 6 bis rue du Centre, 91430 Igny, France
5Elasmo-Lab, Elasmobranch Research Laboratory, Sophie-Rahel-Jansen-Str. 83, 22609 Hamburg, Germany
6Leibniz Institute for the Analysis of Biodiversity Change (LIB), Centre for Taxonomy and Morphology, Zoological Museum, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
*Corresponding author:

ABSTRACT: The shark-like rays (Rhinopristiformes) are among the most threatened species of cartilaginous fishes. The guitarfishes (Rhinobatidae) are one of 5 families in the order, with 62% of species assessed as Vulnerable or higher by the International Union for the Conservation of Nature (IUCN). Species-specific fisheries and conservation efforts have been limited, however, due to unresolved taxonomic issues and poor species descriptions. Presently, there are 3 described species of Rhinobatos from the southwestern Indian Ocean (SWIO): R. austini, R. holcorhynchus, and R. nudidorsalis. These 3 species have been mistaken for one another and are assessed as Data Deficient by the IUCN. Since the descriptions of R. austini and R. nudidorsalis, additional specimens have become available and a rediagnosis of these 3 species is required to clarify their taxonomic status. In the present study, morphometrics from 4 additional congener Indian Ocean species of Rhinobatos assessed by the IUCN were analyzed and serve as comparative material. In addition to a traditional morphological analysis, morphometrics from all 7 species were analyzed using a principal component analysis (PCA) and linear discriminant analysis (LDA). Results show distinct clusters for the SWIO Rhinobatos and indicate the nasal region is effective in differentiating species. R. austini, R. holcorhynchus, and R. nudidorsalis are confirmed as distinct species and are rediagnosed based on new material. These rediagnoses provide taxonomic clarity for SWIO Rhinobatos and will aid in species-specific identification, leading to improvements in conservation and fisheries monitoring and management.

KEY WORDS: Chondrichthyes · Elasmobranchii · Shovelnose rays · Taxonomy · Morphology · Data Deficient

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Cite this article as: Aitchison RM, Ebert DA, Séret B, Weigmann S (2024) Review of three southwestern Indian Ocean species of Rhinobatos (Rhinopristiformes: Rhinobatidae). Endang Species Res 53:67-87.

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