Endemic to Borneo or the Korean Cheju Island? Mystery of mislabelled land snail solved after 170 years (Gastropoda: Cyclophoroidea: Alycaeidae)

The alycaeid Cyclostoma spiracellum Adams & Reeve, 1850 (currently Dicharax spiracellum) was described from Borneo, based on shells from the expedition of HMS Samarang (1843–1846). A comparison with material of nearly all alycaeid species revealed that D. spiracellum is conchologically identical to Alycaeus kurodai Pilsbry & Hirase, 1908, which is described from the Korean Cheju Island. The land operculate snail fauna of Korea and Borneo do not overlap, and D. spiracellum has not been found in Borneo in spite of intensive recent collecting efforts. Therefore, it must be concluded that D. spiracellum does not occur in Borneo and that it was probably obtained when the Samarang visited Cheju Island, and the specimens were most likely mislabelled. As a result, A. kurodai is considered herein as a junior synonym of C. spiracellum, and the type locality of C. spiracellum (Borneo) is corrected to ‘probably Cheju Island, South Korea’. Chamalycaeus kurodai duplicatus Kuroda & Miyanaga, 1943 is treated as Dicharax spiracellum duplicatus (Kuroda & Miyanaga, 1943).