---

Hello Amaira, the answers are there (slightly hidden):
"4. Cheeks bare, at their mid-point 0.5 - 1.1x as wide as the 3rd antennal segment. Femora yellow. Males without oe...vulpina fall."
It's the only one with red femora.

The frontal stripe (or vitta) is not mentioned, that means it is not a relevant character. Sometimes it is red with freshly hatched (teneral) flies.