著者
Nakaya Kazuhiro White William T. Ho Hsuan-Ching
出版者
Nature Publishing Group
雑誌
Scientific reports (ISSN:20452322)
巻号頁・発行日
vol.10, pp.12280, 2020-07-23
被引用文献数
11

Two modes of oviparity are known in cartilaginous fishes, (1) single oviparity where one egg case is retained in an oviduct for a short period and then deposited, quickly followed by another egg case, and (2) multiple oviparity where multiple egg cases are retained in an oviduct for a substantial period and deposited later when the embryo has developed to a large size in each case. Sarawak swellshark Cephaloscyllium sarawakensis of the family Scyliorhinidae from the South China Sea performs a new mode of oviparity, which is named "sustained single oviparity", characterized by a lengthy retention of a single egg case in an oviduct until the embryo attains a sizable length. The resulting fecundity of the Sarawak swellshark within a season is quite low, but this disadvantage is balanced by smaller body, larger neonates and quicker maturation. The Sarawak swellshark is further uniquely characterized by having glassy transparent egg cases, and this is correlated with a vivid polka-dot pattern of the embryos. Five modes of lecithotrophic (yolk-dependent) reproduction, i.e. short single oviparity, sustained single oviparity, multiple oviparity, yolk-sac viviparity of single pregnancy and yolk-sac viviparity of multiple pregnancy were discussed from an evolutionary point of view.
著者
Tatsuta Naoki Imamura Hisashi Nakaya Kazuhiro Kawai Toshio Abe Takuzou Sakaoka Keiichiro Takagi Shogo Yabe Mamoru
雑誌
Memoirs of the Faculty of Fisheries Sciences, Hokkaido University (ISSN:21861927)
巻号頁・発行日
vol.56, no.1, pp.1-64, 2014-05

A taxonomic examination of 3,108 specimens of mesopelagic fishes, collected around the Ogasawara Islands in December 2010 by a beam trawl net operated from the T/S Oshoro-maru, Hokkaido University, Japan, resulted in the recognition of 99 species representing 34 families and 65 genera. Descriptions are provided for all species, two of them〔 a stomiid Eustomias braueri Zugmayer, 1911 and linophrynid Haplophryne mollis (Brauer, 1902)〕 being new records for Japan. Three species, a stomiid Eustomias sp., trachipterid Desmodema sp. and oneirodid Oneirodes sp., could not be identified at the species level