Revision of the species of Chaetocnema from Madagascar (Coleoptera: Chrysomelidae: Alticinae)

The species of flea beetles of the genus Chaetocnema Stephens, 1831 occurring in Madagascar are revised. Four new species (C. cachani, C. hygrophila, C. malgascia and C. orophila) are described and five species (C. bamakoensis Bechyne C. confinis Crotch, C. fuscipennis Scherer, C. ganganensis Bechyne and C. picipes Stephens) are added to the Madagascar fauna. The following new synonymies are proposed: C. wollastoni Baly, 1877 = C. fraterna Harold, 1879 syn. nov. = C. monomorpha Bechyne, 1964 syn. nov.; C. pulla Chapuis, 1879 = C. tantilla Weise, 1910 syn. nov.; C. bilunulata Demaison, 1902 = C. sylvia Bechyne, 1964 syn. nov.; C. vadoni Bechyne, 1948 = C. alaotrensis Bechyne, 1964 syn. nov.; C. gregaria Weise, 1910 = C. insularis Weise, 1910 syn. nov. Lectotypes are designated for C. gregaria Weise, 1910, C. insularis Weise, 1910, C. similis Weise, 1910 and C. tantilla Weise, 1910. A key to all the species is presented. Line drawings of male and female genitalia of all the species are included. Ecological and brief zoogeographical data on some species are given.