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Taxonomic Reinvestigation of Hynobius lichenatus: Description of a New Species and Resurrection of a Previously Described Species from Eastern Japan

A new species of the genus Hynobius from the central part of Tohoku District, Japan, is described. Hynobius lichenatus was divided into three groups based on morphological and molecular analyses, and the boundaries of these groups were delineated. The central part of the Tohoku group was described as Hynobius senzanensis sp. nov., whereas populations from the southern part of Tohoku, the northern part of Kanto, and the eastern part of Hokuriku were resurrected as Hynobius unanngso. Morphometric comparisons revealed that H. lichenatus possesses significantly shorter vomerine teeth length in both sexes compared with the other two species. Additionally, H. lichenatus exhibited a significantly longer tail length compared with H. unanngso. Although the new species and H. unanngso shared similar morphology, they differed significant in the width of their vomerine teeth, and did not form a sister group as closest relatives. Following this taxonomic reassessment, H. lichenatus is now limited to the Tohoku area (comprising Aomori, Iwate, Akita, and Miyagi Prefectures). The boundary between H. lichenatus and the new species is located in the southern part of Akita Prefecture, along the Japan sea side, and the eastern part of Miyagi Prefecture, along the Pacific Ocean side. This study provides insights into the distribution ranges of the three species and a re-evaluation of their habitat status is crucial for their conservation.

Cryptic Species, Mitochondrial DNA, Ou Mountain Range, Species Boundary, Tohoku District

APA Style

Sugawara, H., Fujiwara, A., Azuma, A., Sugawara, R., Kuraishi, M., et al. (2023). Taxonomic Reinvestigation of Hynobius lichenatus: Description of a New Species and Resurrection of a Previously Described Species from Eastern Japan. American Journal of Zoology, 6(2), 26-45.

ACS Style

Sugawara, H.; Fujiwara, A.; Azuma, A.; Sugawara, R.; Kuraishi, M., et al. Taxonomic Reinvestigation of Hynobius lichenatus: Description of a New Species and Resurrection of a Previously Described Species from Eastern Japan. Am. J. Zool. 2023, 6(2), 26-45. doi: 10.11648/j.ajz.20230602.12

AMA Style

Sugawara H, Fujiwara A, Azuma A, Sugawara R, Kuraishi M, et al. Taxonomic Reinvestigation of Hynobius lichenatus: Description of a New Species and Resurrection of a Previously Described Species from Eastern Japan. Am J Zool. 2023;6(2):26-45. doi: 10.11648/j.ajz.20230602.12

Copyright © 2023 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License ( which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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