This timepiece comprises an indicator dial (40), a days-of-the-month mechanism (1) comprising a days-of-the-month mobile (10) and a stepper drive member (13) for driving the days-of-the-month mobile (10), a months mobile (30) coaxial with the days-of-the-month mobile placed beneath said dial (40) and connected to the days-of-the-month mobile (10) by stepper drive means (12, 20) formed so that the months mobile (30) turns through an angle of 30° each month. The dial (40) has twelve windows (41) that are angularly equidistant and the months mobile (30) supports a distinctive zone (32) of which the trajectory passes through said windows (41) and of which the maximum angular extent is 30° and the minimum angular extent corresponds to that of said windows (41).