 Different subspecies of plains zebra were recognised as members of Equus quagga by early researchers , though there was much confusion over which species were valid . Quagga subspecies were described on the basis of differences in striping patterns , but these differences were since attributed to individual variation within the same populations . Some subspecies and even species , such as E. q. danielli and Hippotigris isabellinus , were only based on illustrations ( iconotypes ) of aberrant quagga specimens . Some authors have described the quagga as a kind of wild horse rather than a zebra , and one craniometric study from 1980 seemed to confirm its affiliation with the horse ( Equus caballus ) . It has been pointed out that early morphological studies were erroneous ; using skeletons from stuffed specimens can be problematical , as early taxidermists sometimes used donkey and horse skulls inside their mounts when the originals were unavailable . 
