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| Oncorhynchus biwaensis Fujioka, Kuwahara, Tabata, Fuke & Nakabo, 2025 |
Abstract
Belonging to the Oncorhynchus masou species complex, the Biwa salmon is described as the new species Oncorhynchus biwaensis, a Lake Biwa (Japan) endemic which has been treated as an unidentified species/subspecies since 1990. The new species can be easily distinguished from Masu salmon [Oncorhynchus masou masou (Brevoort 1856)] and Amago salmon (Oncorhynchus masou ishikawae Jordan and McGregor in Jordan and Hubbs 1925) among the species complex in having more pyloric caeca and fewer transverse scales above the lateral line. The identity of Oncorhynchus rhodurus Jordan and McGregor in Jordan and Hubbs 1925, often previously applied to the new species, is shown to differ from the latter. Similarly, O. ishikawae, also previously confused with the new species, is confirmed as Amago salmon. Types of the new species and examples of the other subspecies examined were confirmed as nonhybrids by DNA analysis.
Keywords: Biwa salmon, Lake Biwa, MIG-seq, New species
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| Oncorhynchus biwaensis sp. nov. a Holotype, LBM 1210060173, 151.4 mm SL, from Lake Biwa, when fresh; b holotype, in sprits; c mature male, unregistered specimen, 49.5 cm SL; d mature female, unregistered specimen, 33.7 cm SL |
Oncorhynchus biwaensis sp. nov.
(Standard Japanese name: Biwamasu;
English name: Biwa salmon)
Yasuhiro Fujioka, Masayuki Kuwahara, Ryoichi Tabata, Yusuke Fuke and Tetsuji Nakabo. 2025. The Biwa Salmon, A New Species of Oncorhynchus (Salmonidae) endemic to Lake Biwa, Japan. Ichthyological Research. DOI: doi.org/10.1007/s10228-025-01032-z [21 June 2025]
