  The temperature, field, and field-orientation dependences of the electronic
specific heat Ce of the ironpnictide superconductor KFe2As2 have been
investigated. Thermodynamic evidence of the presence of line nodes is obtained
from the T and $\sqrt{H}$ linear dependences of Ce/T in the low-T and low-H
region. Under a magnetic field rotated within the tetragonal ab plane, a
fourfold oscillation is observed in Ce with a sign change at 0.08Tc. On the
basis of the Doppler-shift analysis, the observed Ce minima in H // [100] at
low T indicate the presence of line nodes somewhere on the Fermi surface where
the Fermi velocity is parallel to the [100] direction; this is consistent with
the octet-line-node scenario proposed recently by a photoemission experiment.
In addition, the low-T Ce/T exhibits an unusual upturn on cooling at moderate
fields only for H // ab, which is understood in terms of the strong Pauli
paramagnetic effect on multiband superconductivity.
