Revision of the genus Arthrotus Motschulsky, 1858 (Coleoptera, Chrysomelidae, Galerucinae) of Taiwan, with notes on color polymorphism.

Seven species of Arthrotus are recognized and redescribed: A.abdominalis (Chûjô, 1962), A.gressitti Kimoto, 1969, A.hirashimai Kimoto, 1969, A.fulvus Chûjô, 1938, A.saigusai Kimoto, 1969, A.tricolor (Chûjô, 1965), and A.testaceus Gressitt & Kimoto, 1963. Also, two new species are described: A.yuae sp. nov. and A.yangi sp. nov. Three new synonyms are proposed: Proegmenataiwana Takizawa, 1978 syn. nov. , Dercetinanakanei Kimoto, 1969 syn. nov. and A.shibatai Kimoto, 1984 syn. nov. Lectotypes are designated for A.fulvus Chûjô, 1938 and Dercestraabdominalis Chûjô, 1962. Color polymorphism of each species is delimited base on more than 1800 specimens.