Somniosus cheni Hsu, Lin & Joung, 2020
Taiwan sleeper shark

Family:  Somniosidae (Sleeper sharks)
Max. size:  14.7 cm TL (male/unsexed); 13.58 cm TL (female)
Environment:  bathydemersal; marine; depth range - 500 m
Distribution:  Northwest Pacific: Taiwan.
Diagnosis:  Vertebrae: 75-79. This species is distinguished from its congeners by the following set of characters: no anal fin; two spineless dorsal fins, first dorsal fin higher and larger than second dorsal fin; short lateral keels on the caudal peduncle, precaudal pits absent; caudal fin is asymmetrical and paddle-shaped, with a relatively short upper lobe and long lower lobe; rhomboid-shaped dermal denticles; teeth dissimilar in upper and lower jaws, upper-jaw teeth small with lanceolate, in 72 rows, lower-jaw teeth semioblique with low roots, in 28 rows; precaudal vertebrae 60-61, caudal vertebrae 15-18, total 75-78; number of turns in spiral valve 25-26 In mid-term embryo stage (12.8-15.0 cm TL); no teeth and dermal denticles; sexes identifiable; caudal keel present. Colouration: body light brown to yellow-grayish (Ref. 123759).
Biology:  This species was collected in canyons surrounded by deep-sea longliner off eastern Taiwan at a depth greater than 500 m (Ref. 123759).
IUCN Red List Status: Data deficient (DD); Date assessed: 06 March 2022 Ref. (130435)
Threat to humans:  harmless


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