Abstract
Simulium (Simulium) yongi sp. nov. is described based on reared females, reared males, pupae and mature larvae collected from Peninsular Malaysia. The immatures of this species were previously misassociated with an adult female holotype of S. (S.) pahangense Takaoka and Davies. This new species is characterized by the combination of the following features : scutum unpatterned, tarsal claws simple and anterior gonapophysis enlarged and widely bare along posterior margin in the female; ventral plate transverse without toothed margins and style with a prominent basal protuberance pointed dorsally in the male; and gill with six filaments per side and cocoon wall-pocket-shaped, with very thin and almost transparent wall in the pupa. This species seems to be related to S. (S.) rudnicki Takaoka and Davies from Langkawi Island, Peninsular Malaysia, S. (S.) ufengense Takaoka from Taiwan, S. (S.) fuzhouense Zhang and Wang from Fujian, south China, and S. (S.) taipokauense Takaoka, Davies and Dudgeon from Hong Kong, from which it differs readily by the darker legs.
