Planonasus

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Planonasus
Systematics
Subclass : Plate gill (Elasmobranchii)
without rank: Sharks (selachii)
Superordinate : Galeomorphii
Order : Ground Sharks (Carcharhiniformes)
Family : Pseudotriakidae
Genre : Planonasus
Scientific name
Planonasus
Weigmann , Stehmann & Thiel , 2013

Planonasus is a genus of small sharks from the order of the ground sharks (Carcharhiniformes). The genus consists of two types. Planonasus parini has so far only beencaught offthe Yemeni island of Socotra and Planonasus indicus is found in the northern Indian Ocean and has beencaughton the coast of the Indian state of Kerala , Sri Lanka and the northern Maldives . The name of the genus refers to the flat snout of the fish (Latin "planus" = flat, "nasus" = nose).

features

Species of planonasus are small deep-sea sharks with a soft, slender body. The specimens caught and examined so far were 34 to 64 cm long. The long head makes up 23.3 to 26.7% of the total length. The snout (in fish the distance from the front edge of the eyes to the tip of the snout) is flattened and accounts for 7.3 to 8.5% of the total length. There is no nictitating membrane or it is only rudimentarily developed. The spray holes are very large and are almost vertical. Their length is 3 to 6 times and their height is 2 to 6 times the diameter of the eye. The very large mouth is angular and 80 to 100% of the width of the head. There are around 110 to 122 rows of teeth in the upper jaw. The teeth are heterodontic, many are comb-like together, others have three or five points. In the lower jaw, all teeth are comb-like. The labial furrow and the anterior labial fold are short. The small placoid scales on the sides of the torso are loosely arranged and do not overlap. There are 7 to 11 scales on an area of ​​one mm². The first dorsal fin lies in front of the base of the pelvic fin, is of medium length and has the shape of a low triangle with a rounded upper tip and a sharply pointed rear end. The second dorsal fin lies above or slightly behind the base of the pelvic fin. It is about the same length or only slightly shorter than the first, but significantly higher. There is no interdorsal ridge . The distance between the dorsal fins is 11.8 to 15.1% of the total length. The anal fin is small and low. It lies behind the second dorsal fin. The tail stalk is short. It has a length of 4 to 6.3% of the total length. The number of vertebrae is 115 to 140. The spiral casing has 12 turns.

species

supporting documents

  1. ↑ a b Ebert, DA, KV Akhilesh and S. Weigmann (2018): 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. Marine Biodiversity, August 2018, DOI: 10.1007 / s12526-018-0915-4