Language: English with bilingual keys in English and Japanese
The Japanese species of the Sepsidae (Diptera), a small family of acalyptrate ﬂies, are revised with reference to faunistics and zoogeography. A total of 43 species in 10 genera are dealt with, and new species, Sepsis hokkaidensis sp. nov. and Dicranosepsis amamiensis sp. nov., are described from and the Ryukyu Archipelago (Amami-Ôshima ls. and lshigaki ls.), respectively. Seven species of the genus Dicranosepsis (D. javanica (de Meijere), D. revocans (Walker), D. sauteri Ozerov, D. splendifica Iwasa, D. transita Ozerov, D. trochanteris lwasa, and D. unipilosa (Duda)) are recorded from Japan for the ﬁrst time. The species recorded under the name of D. bicolor by lwasa ( I980) is actually D. unipilosa (Duda). lwasa (1980, 1995)'s concept of Sepsis monostigma (Thomson) and S. punctum (Fabricius) also proved to be S. latiforceps Duda and S. monostigma (Thomson), respectively. Distribution records of Sepsis indica Wiedemarm from Japan by lwasa (1980, 1995) actually refer to S. testacea Walker. Descriptions of adults are provided for all species, with collecting records, phylogenetic relationships, distribution and bionomics. Illustrations are given for the male fore legs and genitalia of all species. Keys to the Japanese genera and species are also presented. Faunistic composition and of Japanese species are discussed.