Abstract
The various life history strategies seen within the “yoshinobori” species complex of the genus Rhinogobius, which differentiated from an amphidromous ancestor, have been grouped ecologically into amphidromous, fluvial, and lacustrine types. In the Lake Biwa water system, two lacustrine forms exist, a newly discovered, exclusively lentic form and the already well known Rhinogobius sp. OR, which generally undergoes lake–river migration but also includes lentic individuals that share spawning grounds with the former lentic form. Detailed morphological comparisons and allozyme analysis revealed consistently clear differences between the two forms, indicating them to be distinct species. The newly discovered lentic form has many distinctive morphological features that enable it to be distinguished from sympatric Rhinogobius sp. OR: dwarfness, short snout, longitudinally slender pelvic fin, undeveloped frenum with a low lamella, low first dorsal fin in adult males, lesser caudal peduncle depth, scaleless predorsal and ventral areas, and incomplete sensory canals. The lentic form was temporarily named Rhinogobius sp. BW. The life history patterns of the lake-inhabiting populations were separated into two categories: a lake–river migratory lifestyle and an exclusively lentic lifestyle.
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Received: April 27, 2001 / Revised: September 18, 2001 / Accepted: June 20, 2002
Acknowledgments We thank K. Isoda and T. Kunitomo, fishermen in Lake Biwa, for their assistance in the field survey; the staff of Biwakobunkakan for their help in rearing fish and their encouragement; T. Hikida, Kyoto University, for his help in statistical analysis; M. Nishida, Tokyo University, and M. Yuma and A. Iwata, Kyoto University, S. Kimura, Mie University, and T. Suzuki, Amagasaki-kita High School, for their invaluable advice; and A. Rossiter, Lake Biwa Museum, and G.S. Hardy, Thames, New Zealand, for their critical reading of the manuscript and helpful advice. Any experiments and treatments in this study complied with the current laws of Japan.
Correspondence to:Sachiko Takahashi
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Takahashi, S., Okazaki, T. A new lentic form of the “yoshinobori” species complex, Rhinogobius spp. from Lake Biwa, Japan, compared with lake–river migrating Rhinogobius sp. OR. Ichthyol Res 49, 333–339 (2002). https://doi.org/10.1007/s102280200049
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DOI: https://doi.org/10.1007/s102280200049