Yellow and brown shell color morphs of Corbicula fluminea (Bivalvia : Corbiculidae) from Sichuan Province, China, are triploids and tetraploids

Yellow and brown shell color morphs were distinguished in samples of Corbic ula fluminea collected from Anyue County, Sichuan Province, China. Shells o f yellow morphs are straw yellow externally and white internally, while tho se of brown morphs are dark brown and purple, respectively. Karyological an d DNA microfluorometric analyses revealed that yellow and brown morphs, are triploid and tetraploid, respectively. Both are simultaneous hermaphrodite s with non-reductional and biflagellate spermatozoa and brood their larvae in the inner demibranchs like diploid C. fluminea in Taiwan and Japan. Thes e reproductive characteristics are similar to triploid Corbicula leana in J apan, which is self-fertilizing. These results suggest that Corbicula flumi nea at different ploidy levels may also reproduce by self-fertilization.