The 21-year-old striker joined the Spanish top-flight team this month on a five-year deal.
"Granada ... has tonight received official communication from CONMEBOL (South American Football Confederation) confirming that Angulo tested positive in an anti-doping test," the club said in a statement on Thursday.
The Ecuadorian is now banned by Granada until the results of his B sample are known.
Angulo did not feature in the club's La Liga opener on Saturday, a 1-1 draw with Villarreal.
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(Reporting by Adriana Garcia; Editing by Tony Jimenez)
