In an effort to search far and wide, I found this classic beauty on a Spanish dermatological site with no attribution re the fly nor even a reference to the picture itself. The fly looks to be tied on a size 12-14 hook, the tail is pheasant tail fibers. A dubbed body is ribbed with perhaps copper wire. It is not clear but the pheasant tail fibers may extend up the top of the abdomen and be bound down by the ribbing. I can’t quite tell. There is a partridge feather wrapped one to two times and overlaid with a wing of either mallard, gadwall or teal. The head is finished over with red thread and a coating of head cement.
The pattern could be altered with different colored abdomens while maintaining the same tail, hackle, wing.