Abstract: A joint member (1) for mechanically connecting a first panel (51) and a second panel (52) to each other has a body (20) equipped with at least four connecting portions (21, 22, 23, 24) each having a respective seat (31, 32, 33, 34) which receives a fixing element (5). The seats (31, 32, 33, 34) are spaced from each other and, in a plan view of the joint member (1), are positioned at the vertices of a quadrilateral. A first (21) and a second (22) of said connecting portions form a first pair of connecting portions, to be fixed to the first panel (51), whereas a third (23) and a fourth (24) of said connecting portions form a second pair of connecting portions, to be fixed to the second panel (52). Each connecting portion (21, 22, 23, 24) has a first face (41), which is facing the respective panel (51, 52) in use, and a second face (42), which is on an opposite side to the first face (41).