(A–H) pale expression in the dorsal abdomens of male and (A’–H’) female pupae. At the P10 stage, pale expression occurs robustly in the mechanosensory bristle cells of (A and A’) D. melanogaster, (B and B’) D. biarmipes, (C and C’) D. pseudoobscura, and (D and D’) D. willistoni. At the P15(ii) stage, pale expression is robust in the abdominal epidermis of (E and E’) D. melanogaster, (F and F’) D. biarmipes, (G and G’) D. pseudoobscura, and (H and H’) D. willistoni.