Abstract
The freshwater prawn Macrobrachium ustulatum (Nobili, 1899) is distributed throughout the western Pacific Ocean and was first identified in Japan in 2015 on Okinawa Island, Ryukyu Islands. Knowledge of its distribution and habitat is lacking due to difficulties in distinguishing it from a morphologically similar sister species, Macrobrachium australe (Guérin-Méneville, 1838). Here we report an adult male specimen of this species collected from the Kawazu-Yatsu River, Izu Peninsula, Japan. This specimen was morphologically intermediate between the two sister species but was consistent with M. ustulatum based on mitochondrial DNA 16S rRNA and nuclear DNA 28S rRNA sequences. 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.
https://ror.org/02xg1m795 
