AbstractBackgroundThe predatory stink bug genusPicromerusAmyot & Serville, 1843 (Hemiptera,Heteroptera,Pentatomidae,Asopinae) comprises 11 species found in the Northern Hemisphere. In Japan, two species have been recorded to date. However, an easy-to-understand identification method, such as an illustrated key, is lacking. Currently,Picromerusgriseus(Dallas, 1851) has been recorded in Bangladesh, Bhutan, China, Indonesia, Myanmar, Pakistan and Taiwan, but not in Japan.New informationPicromerusgriseuswas recorded in Japan for the first time, based on a single individual collected from grasslands around the fields of Ishigaki Island of the Ryukyu Islands, which belong to the Oriental Region. This discovery represents the easternmost record of the species. An illustrated key to the species ofPicromerusoccurring in Japan is also provided.