A. Roberts drawing of erraticum shows a distinct ventral projection at the tip of the tarsus, which this specimen doesn't appear to show.
B. The drawing for virescens shows a tear-dropped shape at the end of the bulb, which this specimen shows and which appears to be absent from the drawing of erraticum.
C. Roberts drawings show a smooth curve for the proximal spur projection of erraticum but a less smooth curve for virescens, as per this specimen.
D. There is a slight fork at the apex of the projection at D, better fitting virescens.
E. Although the hairs at E are rather tangled and stuck together they appear robust, again better fitting virescens.
F. The longest hairs at F appear longer than the width of the patella, favouring virescens?
Hope this helps.