Many intermediate subspecies have also been proposed, but their validity is uncertain; depending on author, they are either considered primitive forms of an advanced species or advanced forms of a primitive species.[23] Many regional and intermediate subspecies such as M. p. primigenius, M. p. jatzkovi, M. p. sibiricus, M. p. fraasi, M. p. leith-adamsi, M. p. hydruntinus, M. p. astensis, M. p. ame