 Although 17 subspecies are recognized , this number may be excessive . Using a cluster analysis of anatomical characters , Dixon and others found that black @-@ tailed jackrabbit subspecies separated into two distinct groups that are geographically separated west and east of the Colorado Rocky Mountains and the Colorado River . They suggested only two infrataxa are warranted : the western subspecies L. c. californicus and the eastern subspecies L. c. texianus . 
 Although 17 subspecies are recognized , this number may be excessive . Using a cluster analysis of anatomical characters , Dixon and others found that black @-@ tailed jackrabbit subspecies separated into two distinct groups <a href='null_relcl' title='1'><mark>that</mark></a>are geographically separated west and east of the Colorado Rocky Mountains and the Colorado River . They suggested only two infrataxa are warranted : the western subspecies L. c. californicus and the eastern subspecies L. c. texianus . 
Although 17 subspecies r recognized , dis number may be excessive . usin a cluster analysis of anatomical characters , Dixon and others found dat black @-@ tailed jackrabbit subspecies separated into 2 distinct groups are geographically separated west and east of the Colorado Rocky Mountains and the Colorado River . They suggested only tw2nfrataxa are warranted : the western subspecies L. c. californicus and da eastern subspecies L. c. texianus .