Who inhabits the world’s deepest crater lake? A taxonomic review of Corbicula (Bivalvia: Cyrenidae) clams from Lake Toba, North Sumatra, Indonesia

A taxonomic reassessment of native and invasive species of Corbicula clams (Bivalvia: Cyrenidae) from the Russian Far East and Korea

Currently, the validity of many nominal bivalve species of the genus Corbicula endemic to the Russian Far East and South Korea needs a critical reassessment. In this study, we clarify the taxonomic status of Corbicula species of this area based on a combination of molecular genetic, conchological and anatomical data. According to our results, four Corbicula lineages, corresponding to the nominal species Corbicula japonica, Corbicula elatior, Corbicula leana and Corbicula fluminea, can be delineated in samples collected in the Primorye and Khabarovsk regions of Russia and South Korea. Two species endemic to the Russian Far East (i.e. Corbicula finitima and Corbicula lindholmi) are considered here as junior synonyms of the species C. japonica, which is widely distributed in estuarine habitats around the Japanese Archipelago, Sakhalin Island, southern Kurile Islands, Primorye and Khabarovsk regions, Korean Peninsula and China. Three nominal species described from the Lower Amur basin (Corbicula amurensis, Corbicula nevelskoyi and Corbicula sirotskii) appeared to be synonyms of C. elatior, whose range covers the Korean Peninsula, Primorye and Khabarovsk regions and, perhaps, China. We delineated several colour morphs of C. fluminea and C. japonica. The distinctness between these colour morphs can be attributed to both heritable and environmental factors.