Arena Pharmaceuticals Inc. said Monday it transferred marketing rights for the diet pill Belviq to its partner Eisai Co. Ltd., which will market the drug in the U.S. and apply for approval in other North and South American countries. Arena said it transferred the FDA application for the drug to the Japanese pharmaceutical company, which plans to submit it for approval in Mexico, Brazil, Canada and other countries. The FDA approved Belviq in late June for adults who are obese or are overweight with at least one medical complication, such as diabetes or high cholesterol. It was the first FDA approval of a new drug for long-term weight loss in 13 years.