GLOBAL : CORRESPONDENTS’ COURSES : Times writers around the world reveal the names of their favoritelittle-known restaurants : RIO DE JANEIRO

The restaurant is called Guimas, from the family names of the two Brazilian couples who started it five years ago.

The food is imaginative and well cooked and served in an informal setting where it is interesting to watch and hear the local customers. They are a relaxed mix of artists, television personalities and professionals.

One of the owners who is always on hand is English- and French-speaking Francisco (Chico) Mascarenhas. The son of a Portuguese diplomat in Rio de Janeiro, he used to travel the world as a magazine photographer. He got some of the ideas for Guimas’ French-Portuguese menu during a long assignment in Paris.

For $25, which also covers the cost of a bottle of wine, a couple can choose from such meat dishes as filet boursin with a pate sauce, duck roasted in a rich dark gravy, trout with a leek sauce or flounder with a Roquefort sauce. There is a self-service salad bar and a delicious dessert of passion-fruit pastry called maracuja in Brazil.

Guimas is open for lunch and dinner Monday through Saturday and for lunch on Sundays, except in February when it closes for Carnival. It seats only 36 people and gets crowded in the evening. When the waiting line spills out onto the mosaic sidewalk, waiters provide drinks, including a Brazilian specialty, a lemony rum sour called caipirinha.

Reservations are accepted, but not for after 9 p.m., even though the restaurant is open until after midnight.

Guimas, Rua Jose Roberto Macedo Soares No. 5, just off Santos Dumont Square in the lower Gavea section; telephone 259-7996.