Context : CoRoT-2 , the second planet-hosting star discovered by the CoRoT satellite , is a young and active star .
A total of 77 transits were observed for this system over a period of 135 days .

Aims : Small modulations detected in the optical light curve of the planetary transits are used to study the position , size , intensity , and temporal evolution of the photospheric spots on the surface of the star that are occulted by the planetary disk .

Methods : We apply a spot model to these variations and create a spot map of the stellar surface of CoRoT-2 within the transit band for every transit .
From these maps , we estimate the stellar rotation period and obtain the longitudes of the spots in a reference frame rotating with the star .
Moreover , the spots temporal evolution is determined .
This model achieves a spatial resolution of 2 ^ { \circ } .

Results : Mapping of 392 spots vs. longitude indicates the presence of a region free of spots , close to the equator , reminiscent of the coronal holes observed on the Sun during periods of maximum activity .
With this interpretation , the stellar rotation period within the transit latitudes of -14 \aas@@fstack { \circ } 6 \pm 10 ^ { \circ } is obtained from the auto-correlation function of the time integrated spot flux deficit , yielding a rotation period of 4.48 days .
With this period , the temporal evolution of the spot surface coverage in individual 20 ^ { \circ } longitude bins has periodicities ranging from 9 to 53 days with an average value of 31 \pm 15 days .
On the other hand , the longitude integrated spot flux , that is independent of the stellar rotation period , oscillates with a periodicity of 17.7 days , which false-alarm probability is \sim 3 % .

Conclusions : The rotation period of 4.48 days obtained here is shorter than the 4.54 days as derived from the out-of-transit light modulation .
Since the transit data samples a region close to the stellar equator , while the period determined from out-of-transit data reflects the average rotation of the star , this is taken as an indication of a latitudinal differential rotation of about 3 % or 0.042 rad/d .