Department of Biology

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Eva Egelyng Sigsgaard

The Sandy Zebra Shark: A New Color Morph of the Zebra Shark Stegostoma tigrinum, with a Redescription of the Species and a Revision of Its Nomenclature

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DOI

  • Rikke Beckmann Dahl, Acad Sinica, Academia Sinica - Taiwan, Biodivers Res Ctr
  • ,
  • Eva Egelyng Sigsgaard
  • Gorret Mwangi, Kenya Trop Sealife Ltd
  • ,
  • Philip Francis Thomsen
  • Rene Dalsgaard Jorgensen, Kenya Trop Sealife Ltd
  • ,
  • Felipe de Oliveira Torquato, University of Copenhagen
  • ,
  • Lars Olsen, Danish Natl Aquarium Den Bla Planet
  • ,
  • Peter Rask Moller, University of Copenhagen

The Zebra Shark, in recent years known as Stegostoma fasciatum (Hermann, 1783), is well known for its dramatic ontogenetic change of color pattern, from striped ("zebra'') juveniles to spotted ("leopard'') adults. Nevertheless, many aspects of the species' biology, ecology, and morphology are still unknown or inadequately described, and its nomenclature is contentious. This study introduces a hitherto undescribed color morph of the Zebra Shark and provides an updated diagnosis and redescription of the species. Firstly, we establish that the Zebra Shark remains a single species based on genetic data from mitochondrial COI and ND4 markers. Secondly, through morphological analyses, we conclude that there are two morphs of the species, the known, zebra striped morph and a new, sandy colored morph. Both morphs were studied morphometrically to expose any ontogenetic changes, such as a decrease in the relative length of the tail with increasing total length (TL). The external coloration pattern clearly differentiates the two morphs, and both morphs can be further divided into three stages based on color pattern and size: juveniles (255-562 mm TL), transitionals (562-1395 mm TL), and adults (>1300 mm TL). The transitional sandy morph is dorsally covered by a swirly pattern of thin, dark brown bands edged with freckle-like brown spots. The adults are a uniform sandy beige, partially covered with brown freckles. A mature male of the zebra morph displayed a yet unknown feature of the claspers: a small, triangular spike extruding from the dorsal terminal of the clasper glands. Finally, we reviewed the nomenclature of the species and suggest that the original name Stegostoma tigrinum Forster, 1781 should be used as the senior synonym for the species.

Original languageEnglish
JournalCopeia
Volume107
Issue3
Pages (from-to)524-541
Number of pages18
ISSN0045-8511
DOIs
Publication statusPublished - Sep 2019

    Research areas

  • FASCIATUM, IDENTIFICATION, DIVERSITY, ABUNDANCE, RAY

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