* Marib Light crude OSP unchanged at parity to dated Brent
* Arcadia to buy Masila crude (Adds detail)
TOKYO Nov 21 (Reuters) - Yemen set the official selling price of its Masila crude for loading in January at a premium of $2.57 a barrel to dated Brent, the government said late on Sunday.
The January OSP, likely to be a record for the grade, was up $1.24 from December.
Arcadia was the highest bidder and will load 1.95 million barrels of the available 2.5 million barrels of Masila crude in January, the government said in an email.
Yemen is inviting bids to buy the remaining 550,000 barrels at the January OSP.
Yemen also set the official selling price for Marib Light crude for January at parity to dated Brent, unchanged from the previous month.
The nation did not announce quantities for Marib Light for January or the buyer. (Reporting by Osamu Tsukimori; Editing by Joseph Radford)