Since M4.5 - M9 dwarfs exhibit equatorial rotation velocities of order 10 kms ^ { -1 } on average , radial velocity surveys targeting this stellar population will likely need to find methods to effectively remove starspot jitter .
We present the first high resolution Doppler images of the M4.5 dwarf , GJ 791.2A , and the M9 dwarf , LP 944-20 .
The time series spectra of both objects reveal numerous line profile distortions over the rotation period of each star which we interpret as starspots .
The transient distortions are modelled with spot/photosphere contrast ratios that correspond to model atmosphere temperature differences of T _ { phot } - T _ { spot } = 300 K and 200 K. GJ 791.2A is a fully convective star with v sin i = 35.1 kms ^ { -1 } .
Although we find more starspot structure at high latitudes , we reconstruct spots at a range of phases and latitudes with a mean spot filling of \sim 3 % .
LP 944-20 is one of the brightest known late-M dwarfs , with spectral type M9V and v sin i = 30.8 kms ^ { -1 } .
Its spectral time series exhibits two dominant transient line distortions that are reconstructed as high latitude spots , while a mean spot filling factor of only 1.5 % is found .
The occurrence of low-contrast spots at predominantly high latitudes , which we see in both targets here , is in general likely to be responsible for the low amplitude photometric variability seen in late-M dwarfs .
For GJ 791.2A , the radial velocities induced by the starspot features yield an r.m.s .
velocity variability of 138 ms ^ { -1 } , which can be reduced by a factor of 1.9 using our reconstructed surface brightness distributions .