Planonasus indicus sp. n., a new species of pygmy false catshark (Chondrichthyes: Carcharhiniformes: Pseudotriakidae), with a revised diagnosis of the genus and key to the family
A new species of the genus Planonasus is described from off southwestern India and Sri Lanka in the northern Indian Ocean. The new species occurs along the upper continental slope from 200 to 1000 m deep and was landed in fisheries for gulper sharks (Centrophorus spp.). Planonasus indicus sp. n. externally closely resembles P. parini (Carcharhiniformes: Pseudotriakidae), the only other member of the genus. It can be distinguished from P. parini by a combination of morphological characters including absence of oral papillae, lack of a distinct white mark on the free rear tip of the first dorsal fin, sides and underside of head, as well as fin edges that are similar in color as body (vs. dusky), more tooth rows in the lower jaw, shorter labial furrows, longer and less high spiracles, proportionally higher, more angular dorsal fins, especially the second dorsal fin, proportionally longer pectoral fins, a proportionally larger anal fin, longer distances from the snout tip to the origins of the caudal fin, both dorsal fins and the pelvic fins, as well as to the vent, and shorter distances for preorbital snout, prepectoral length, pelvic midpoint to second dorsal fin origin, and pelvic-anal space. A revised diagnosis of the genus and key to the family is also provided.
KeywordsDeep-sea Elasmobranch Shark Systematics Taxonomy Northern Indian Ocean India
The following individuals are sincerely thanked for their assistance and support on various aspects of this project: SciGraphics (http://www.scigraphics.de) for making the drawings for the key to the family; Dave Catania and Jon Fong (California Academy Sciences), the Director, ICAR-CMFRI, for the facilities and support provided; Ganga, Hashim, Bineesh, and Shanis for their support in field and lab; Daniel Fernando, Akshay Tanna, Rosalind Brown, and Gobiraj (Blue Resources Trust, Sri Lanka); Jann and Tom Rudkin and the REX Fund at the University of Kansas Biodiversity Institute; Kirsten Jensen (University of Kansas), Janine N. Caira (University of Connecticut), Loren Caira, and Marsha Englebrecht for logistical and financial support of the 2018 expedition during which the paratype specimen from Sri Lanka was collected; Ralf Thiel (ZMH) for granting access to the specimens in the ZMH collection for examinations and to photo- and radiography facilities at ZMH; Irina Eidus (ZMH) for her help with the radiography and collection database; Nicolas Straube (ZSM) for his help with taking photographs of the opened mouth of the holotype of Planonasus parini and for kindly helping with the PCA; and Alastair Graham, Peter Last, and John Pogonoski (CSIRO) for providing information regarding the absence of an interdorsal ridge in Gollum, as well as photographs of teeth and collection data of G. attenuatus and G. suluensis. Moss Landing Marine Laboratories provided additional support for this project.
Jann and Tom Rudkin and the REX Fund at the University of Kansas Biodiversity Institute supported the 2018 Sri Lanka expedition where the paratype (BRT-I:0029) was collected.
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for care and use of animals were followed by the authors.
Sampling and field studies
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.
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