** Jefferies says Aphria trades at a marked discount to peers due to an overhang from a short-seller report and impairment charges
** Says Aphria is top pick in the cannabis space, raises PT on U.S.-listed shares by 10 cents to $8.40 and maintains "buy"
** Says APHA has strong existing Canadian medical business, well segmented branding approach to recreational market, supportive capacity, industry's best operations in important market of Germany and real potential for U.S. optionality
** Aphria should trade at similar levels to other global players - Jefferies
** Up to Tuesday's close, the Canadian-listed stock had fallen 13.6% this year and the U.S.-listed stock 8.3% (Reporting by Arunima Kumar in Bengaluru)