A review of the genus Platyrhina (Chondrichthys: Platyrhinidae) from the northwestern Pacific, with descriptions of two new species

The genus Platyrhina from the northwestern Pacific was reviewed, including a redescription and neotype proposal for Platyrhina sinensis (Bloch and Schneider 1801), and the description of two new species. Platyrhina limboonkengi Tang 1933 is relegated to the synonymy of P. sinensis, both species having two rows of hooked thorns on the mid-dorsum of the tail. Specimens previously widely identified as P. sinensis, but characterized by one row of such hooked thorns, represented an undescribed species, herein named Platyrhina tangi Iwatsuki, Zhang and Nakaya sp. nov. Platyrhina hyugaensis Iwatsuki, Miyamoto and Nakaya sp. nov., known from specimens limited primarily to the Hyuga Nada Sea, off Miyazaki, the Pacific coast of southern Japan, is similar to P. tangi in having one row of hooked thorns on the mid-dorsum of the trunk and tail, but differs in having larger hooked thorns, not encircled by light yellow or white pigment on the orbital, nape and scapular regions, and a pair of hooked thorns (absent in P. tangi) anteriorly on the scapular region. Nominal species are discussed and key to northwestern Pacific species of Platyrhina is provided.