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Aims: We carried out high-resolution spectroscopy and BV(I)_C photometricmonitoring of the two fastest late-type rotators in the nearby Beta Pictorismoving group, HD199143 (F7V) and CD-641208 (K7V). The motivation for this workis to investigate the rotation periods and photospheric spot patterns of thesevery young stars, with a longer term view to probing the evolution of rotationand magnetic activity during the early phases of main-sequence evolution. Wealso aim to derive information on key physical parameters, such as rotationalvelocity and rotation period. Methods: We applied maximum entropy (ME) andTikhonov regularizing (TR) criteria to derive the surface spot mapdistributions of the optical modulation observed in HD199143 (F7 V) andCD-641208 (K7V). We also used cross-correlation techniques to determine stellarparameters such as radial velocities and rotational velocities. Lomb-Scargleperiodograms were used to obtain the rotational periods from differentialmagnitude time series. Results: We find periods and inclinations of 0.356 daysand 21.5deg for HD199143, and 0.355 days and 50.1deg for CD-641208. The spotmaps of HD199143 obtained from the ME and TR methods are very similar, althoughthe latter gives a smoother distribution of the filling factor. Maps obtainedat two different epochs three weeks apart show a remarkable increase in spotcoverage amounting to ~7% of the surface of the photosphere over a time periodof only ~20 days. The spot maps of CD-641208 from the two methods show goodlongitudinal agreement, whereas the latitude range of the spots is extended tocover the whole visible hemisphere in the TR map. The distributions obtainedfrom the first light curve of HD199143 show the presence of an extended andasymmetric active longitude with the maximum filling factor at longitude~325degree.

Starspots on the fastest rotators in the Beta Pic moving group