Hylemya vagans

Having had little experience keying this family I struggled using the main key to Anthomyiidae genera at the Dipterists Forum, reaching a conclusion that didn't match up with the diagrams of genitalia. I had forgotten about the simplified key to common species that follows and is much easier to use, and fairly quickly this led me to Hylemya vagans. The genitalia matched except for one feature, so I then checked the full key to Helymya and Helymyza genera. This also led to vagans, so long as I took the mid and hind femora to be black not yellow like the tibia - in reality they were dark blackish yellow, clearly and contrastingly blacker than the tibia but not really black (this is at the point of examining the specimen several months after death - the femora do look pretty black in my photos of the live fly).

The genitalia seemed fine except for one character, the tip of the cercal plate. In the diagram in the key it showed a single point, whereas my specimen clearly had a double point (W-shaped). This bothered me as I would have expected it to be consistent, so I spent some time going through the other genitalia diagrams. One species shared this character but wasn't as close in other respects, and a check of the keys ruled that out firmly. Finally I had a look online and came across the spessart-fliegen.de website which included this photo of Hylemya vagans with a W-shaped tip to the cercal plate (albeit a slightly shallower W than on mine). So, presumbaly, either the diagram in the key is wrong or (more likely I should imagine) this character is variable.

male Hylemya vagans showing close-up of acrostichals, hind femur and tibia, circal plate and surstyli (2 flat views and one from side), 5th sternite and aedeagus and gonites (2 orientations), North Elmham Cathedral Meadows (Norfolk, UK), 28th April 2021