The freshwater prawn Macrobrachium ustulatum is distributed throughout the western Pacific Ocean and was first identified in Japan in 2015 on Okinawa Island, Ryukyu Islands. Here we report an adult male specimen of this species collected from the small river in Izu Peninsula, Japan. This is not only the northernmost record of M. ustulatum, but also the second record from Japan based on a single male specimen, and the first from Honshu.
Figure: Macrobrachium ustulatum obtained in this study. This is the first male specimen of this species found in Japan.
