I had this fish myself as a lifer, caught in Fossil Creek (Article HERE), but removed this species when Headwater Chub was reclassified as a Roundtail Chub and that was accepted by Arizona Fish and Game. Is there something new that split this species out again?
Nope. Nothing new regarding chub in Arizona. The fish formerly known as headwater chub is still classified as roundtail chub. When that reclassification occured, it was confirmed by the American Fisheries Society taxonmic committee and accepted by the US Fish and Wildlife Service. I think its a done deal for quite a while. It would take a pile of new studies to outweigh the dozens of genetic and morphometric studies that led to the reclassification.