Key as followingt Evans.
1a, 1b, 12a, 19a ...FW ce3llspot is nearer apex than base., 19b, 19c , 21 (19d) HW cilia narrowly white or brown; FW spot 3 conjoined to band ; only outer spot in space 1b...C. nigricans.
Note this individual match key line 19a well, ie FW cellspot is nearer FW apex than base.