A medically important genus of amphibious freshwater operculate snails of the family Hydrobiidae (subfamily Hydrobiinae; subclass Prosobranchiata). In Asia, several subspecies of O. hupensis serve as intermediate hosts of the oriental blood fluke, Schistosoma japonicum. [onco- + G. melas (melan-), black]
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On·co·me·la·nia .äŋ-kō-mi-'lā-nē-ə n a genus of amphibious snails (family Bulimidae) of Asian and Pacific island freshwaters that comprises forms which are intermediate hosts of a schistosome (Schistosoma japonicum)
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On·co·me·la·nia (ong″ko-mə-laґne-ə) a genus of fresh water snails of the family Bulimidae, found in eastern Asia and nearby Pacific islands; some species transmit schistosomiasis japonica. Formerly called Katayama.Medical dictionary. 2011.