UpStairs on the Square, the Harvard Square restaurant known for its zebra-print dining room and afternoon tea, will close on New Year’s Eve after 31 years. Owners Mary-Catherine Deibel and Deborah Hughes made the announcement via e-mail. “The current landlord has decided to sell the iconic Harvard Square landmark building at 91 Winthrop Street,” they write. “We founded our first restaurant UpStairs at the Pudding in 1982 because we loved giving dinner parties, and we’ve never stopped thinking of our restaurant as an excuse to host a wonderful soirée every night. Our hospitality — dispensed liberally and happily — is meant to foster a sense of gaiety, of festivity, of well-being — for guest and staff alike. You know — just like at a fabulous dinner party!” In keeping with this tradition, Deibel and Hughes are planning a series of farewell events leading up to the closing, concluding with a “Grand Finale New Year’s Eve Fete” with dancing and champagne.