The spider-tailed horned viper (Pseudocerastes urarachnoides) is a species of viper endemic to western Iran which was described in 2006. The head looks very similar to that of other Pseudocerastes species in the region, but the spider-tailed horned viper has a unique tail that has a bulb-like end that is bordered by long drooping scales that give it the appearance of a spider. The tail tip is waved around and used to lure insectivorous birds to within striking range.