Revision of the Simulium (Simulium) multistriatum species-group (Diptera: Simuliidae) in Sumatra, Indonesia: Descriptions of three new species and a redescription of the male and pupa of S. (S.) fenestratum Edwards.

Adults and pupae of black flies assigned to the Simulium (Simulium) multistriatum species-group collected from Sumatra, Indonesia in 1992 and 1994 were reexamined. As a result, three undescribed species were found besides S. (S.) fenestratum Edwards, the only species in this species-group so far described from Sumatra. These undescribed species are described as new: S. (S.) mutaralamense sp. nov., which is characterized in the female by the haired basal portion of the radial vein, in the male by the number of upper-eye (large) facets in 18 or 19 vertical columns and 19 or 20 horizontal rows and hind basitarsus entirely darkened, and in the pupa by the gill with eight filaments widely divergent when viewed laterally; S. (S.) lubuksulasihense sp. nov., which is similar to S. (S.) mutaralamense sp. nov., but differs by the male hind basitarsus yellow on its basal one-third; and S. (S.) liwaense sp. nov., which is characterized in the male by the smaller number of upper-eye (large) facets in 14 or 15 vertical columns and 16 horizontal rows, and in the pupa by the gill with eight filaments moderately divergent when viewed laterally, and all three anterodorsal trichomes unbranched on each side of the thorax. Taxonomic notes to distinguish these new species from their related species are given. The male and pupa of S. (S.) fenestratum are redescribed.