SHARKS FROM THE AMIRANTES ISLANDS, SEYCHELLES, WITH A DESCRIPTION OF TWO NEW SPECIES OF SQUALOIDS FROM THE DEEP SEA

Abstract

During a research cruise conducted in December 1998 off Alphonse Island, Seychelles, sharks were collected. A large specimen identified as Pseudotriakis microdon presents morphometrics different from those of specimens from other areas. Carcharhinus amblyrhynchos, C. albimarginatus, and Sphyrna lewini are compared with Red Sea populations. Centroscymnus coelolepis is recorded for the first time in the western Pacific. Species from the family Squalidae were collected and identified as: Centrophorus granulosus, Centrophorus seychellorum n. sp., and Squalus lalannei n. sp. Squalus lalannei belongs to the acanthias group sharing the posterior position of the first dorsal fin, a simple nasal flap, and a low number of precaudal vertebrae. It differs from Squalus acanthias by a higher and wider first dorsal, a smaller second dorsal positioned posteriorly, and the lack of white spots. Centrophorus seychellorum n.sp. is closely related to C. granu-losus, but differs by its snout shape and size. It is shown that this species presents sexual dimorphism in snout length and shape of the upper jaw teeth. The validity of characteristics such as snout-length, shape of dermal denticles, and pectoral fins for squalid identification is discussed.