Thambemyia Oldroyd is a marine shore dolichopodid genus in the aphrosyline subgroup of the subfamily Hydrophorinae. The genus was erected by Oldroyd (1956) based on the greatly elongated proboscis of the Malaysian species T. pagdeni Oldroyd. Since the early 1980’s the generic limits of Thambemyia have been in flux as a result of differing opinions regarding the proposed synonymy of the related genus Conchopus Takagi, 1965 by Meuffels & Grootaert (1984). Masunaga et al. (2005) argued to retain the generic status of Conchopus in a much restricted sense (i.e., the rectus species group of Takagi), but did not provide evidence to support that classification, however later Masunaga in Zhu et al. (2005) appears to have reversed this decision. Recent catalogs have all treated Conchopus as a junior synonym of Thambemyia (Bickel & Dyte 1989; Pollet et al. 2004; Yang et al. 2006). Presently Thambemyia (sensu Meuffels & Grootaert 1984) includes 24 described species from Japan, China and the Hawaiian Islands (Yang et al. 2006). Masunaga & Saigusa (2006) reported an additional five undescribed species (as Conchopus) from the Hawaiian Islands.