Ubristes (Hypselosyrphus) trigonus (Hull)  

Hypselosyrphus is based on an Ubristes species in which the 4th abdominal segment is short and triangular. As with Stipomorpha, this character is considered only of species group value (Cheng and Thompson 2008).

Ubristes (Hypselosyrphus) species have postmetacoxal bridge complete; abdomen triangular, broad basally, strongly narrowed apically, short, almost equilateral in shape; metatibia with long pile along dorsal edge, forming a distinct brush of pile; basoflagellomere not furcate, usually not greatly elongate; metabasitarsomere not enlarged; and vein R4+5 with an appendix extending posteriorly into cell R4+5.