  We present lithium abundances for ~50 X-ray selected candidate members of the
30-50 Myr old open clusters IC 2602 and IC 2391. These data enlarge and extend
to cooler temperatures previous Li surveys of these clusters by Stauffer et al.
(1989) and Randich et al. (1997). We also give for the first time an estimate
of the metallicity of the two clusters which turns out to be close to solar.
Radial velocity measurements together with Halpha chromospheric emission and
the presence/absence of other spectroscopic features are used to ascertain the
membership status for the sample stars not yet confirmed as cluster members;
rotational velocities have also been determined for all sample stars. Stars
more massive than ~1 Mo in both clusters show no sign of significant Li
depletion, while lower mass stars are all lithium depleted, with the amount of
Li depletion increasing to cooler temperatures. We confirm that the late G and
early K stars in IC 2602 present a star-to-star scatter in Li abundances
similar to, but not as large as the one in the Pleiades. A scatter is also seen
among late-K and M dwarfs. Unlike in the Pleiades and Alpha Per clusters, the
scatter among early-K stars in IC 2602 shows only marginal correlation with
rotation. Our data suggest that the drop-off of lithium towards lower masses
may start at an earlier color in IC 2391 than in IC 2602, but larger cluster
samples are needed to confirm this result. In addition, whereas G and early K
stars in the two clusters are, on average, more Li rich than their counterparts
in the Pleiades, a fraction of the coolest stars, in particular in IC 2391, are
as depleted as as the lowest-Li Pleiades stars of the same mass. If they
continue depleting Li on their way to the main sequence, they are expected to
be more Li depleted than the Pleiades at the age of the latter cluster.
