Key to separate the Nearctic Hemeromyia species described so far

1 Head completely black; antenna completely dark brown; gena without silver dusting; notopleuron shining; antennal grooves extending from antennal bases to mouth opening..................................... 2 ( washingtona species group)

- Frons distinctly yellow anteriorly, gena and face more or less yellow; antenna at least partly light orange; gena silver microtomentose; notopleuron microtomentose; antennal grooves extending downwards from antennal bases for about 3/4 of face length only..................................( obscura species group) obscura Coquillett, 1902 & undescribed species

2 Facial carina broad (about 1/7 of width of face; 1 specimen examined); face broad (narrowest width of face: maximum width

of head = 0.4; 1 specimen examined); frontal triangle reaching anteriorly about 2/3 distance from anterior ocellus to frontal margin; anepimeron distinctly stronger microtomentose than adjacent pleura; costa with scattered obvious setae beyond radial vein R1; basal tarsi orange and distinctly contrasting to the brown tarsi; larger species (wing length 2.6 mm; 1 specimen examined); reported from several locations across the USA and Canada....................... washingtona (Melander, 1913) - Facial carina narrow (less than 1/10 of width of face); face in most specimens narrower (narrowest width of face: maximum width of head = 0.33–0.41); frontal triangle reaching anteriorly about half distance from anterior ocellus to frontal margin; anepimeron subshining as adjacent pleura; costa without obvious setae beyond radial vein R1; basal tarsi orange brown and hardly contrasting to the brown tarsi; smaller species (wing length 1.3–1.7 mm); so far only known from California............................................................................................ alberichae spec. nov.