Thereva nelsoni Holston & Irwin, 2005

Thereva nelsoni is distinguished from similar species by the combination of extensive greyish yellow tomentum, yellow setae of the thorax and abdomen, and yellow halter knob.  The wing membrane is hyaline, almost transparent; the female frons is shining medially with the tomentum of the upper frons restricted to the area adjacent to the ocellar tubercle.