Eurystylus luteus Hsiao, 1941

In Japan and Taiwan, three species, Eurystylus coelestialium, E. luteus, and E. sauteri, have been reported. However, our attempts to identify the specimens from these areas revealed that the Japanese and Taiwanese populations which have been assigned to E. luteus should belong to E. sauteri, and all previous records of E. sauteri from SW Japan and Taiwan were incorrect. Judging from the overall similarities and distribution patterns it is highly probable that luteus (described by Hsiao from Anhui, China in 1941) and sauteri (by Poppius from Taiwan in 1915) are conspecific. The holotype of luteus is unfortunately female, but the male endosomal illustrations based on Chinese materials (Zheng & Chen, 1991; Zheng et al., 2004) doubtlessly coincide with those found in Japan and Taiwan. We therefore refrain from using luteus for relevant Japanese and Taiwanese specimens, to avoid further taxonomic confusion (Yasunaga et al., 2017a).