The first record of <i>Betaeus levifrons</i> (Decapoda: Caridea: Alpheidae) from the Pacific Coast of Japan, with remarks on symbiosis with <i>Upogebia major</i>

Abstract Five specimens of the rare alpheid shrimp Betaeus levifrons Vinogradov, 1950 were collected from the burrows of the mud-shrimp Upogebia major (De Haan, 1841) in Akkeshi and Usu Bays, along the Pacific coast of Hokkaido, Japan. As B. levifrons has been previously only reported from the Russian coast of the Sea of Japan, the Hokkaido specimens represent the first record of this species from the western Pacific coast as well as a new to the Japanese fauna. Ovigerous females of B. levifrons were recorded for the first time based on specimens. This study provides additional data on this species, including its distribution, colour variation, and DNA sequences of the mitochondrial 16S rRNA and cytochrome c oxidase subunit I barcoding regions. Lastly, we revised the available data on the symbiotic fauna of U. major .