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Press Releases

DATE2025.01.22 #Press Releases

Three New Species of Freshwater Snail Discovered from Honshu, Japan

-Diversification of Lake Biwa lineages outside the lake

Summary

In Lake Biwa, an ancient lake located in centeral Japan, the freshwater snail genus Semisulcospira has adaptively radiated. In the genus, most species that diversified in the lake are still distributed only in the Lake Biwa system. However, S. kurodai is the only species known to be expanded to a wide area from Shizuoka Prefecture to Okayama Prefecture, despite its close relationships to the Lake Biwa endemics. Although a previous study had found four genetically distinct lineages within S. kurodai, their taxonomic accounts had not been investigated.

A research group led by Naoto Sawada, a Doctoral student at the Graduate School of Science, Kyoto University (currently a Project Researcher at the School of Science, The University of Tokyo), Yusuke Fuke, a Doctoral student at the Graduate School of Science, Kyoto University (currently a Researcher at the National Institute of Genetics), and Professor Osamu Miura, Faculty of Agriculture and Marine Science, Kochi University, has arranged the taxonomic account of the S. kurodai using genetic and morphological analyses. In addition, they described three new species, S. masudai (distributed in Hyogo and Tottori Prefectures), S. praecursa (in Shizuoka and Aichi Prefectures), and S. miurai (in Okayama Prefecture).

These four species can be distinguished from each other by the angle and sculpture of their teleoconchs, as well as the morphology of their protoconchs and radulae. It was also clarified that female of all species possess larger teleoconchs than males. Genetic analysis revealed four geographic groups within S. kurodai, and suggested that this species originated not directly around Lake Biwa but in the Chugoku District, and its current distribution had been formed by the expansion to the east. The results of this research re-evaluate the species richness of the genus Semisulcospira and partially elucidate the complex diversification history of the lacustrine lineage of the genus.

This research was published online in Systematics and Biodiversity, an international journal of biology, on January 21, 2025.


Figure: from left to right: teleoconch specimens of Semisulcospira kurodai, S. masudai sp. nov., S. praecursa sp. nov., and S. miurai sp. nov., and a living animal of S. miurai sp. nov.

Related link: Kyoto University

Journal

Journal name
Systematics and Biodiversity
Title of paper