  Physical properties for the late-lanthanide-based RNiC2 (R = Dy, Ho, Er, and
Tm) ternary compounds are reported. All the compounds show antiferromagnetic
ground state with the N\'eel temperature ranging from 3.4 K for HoNiC2 to 8.5 K
for ErNiC2. The results of the transport and galvanomagnetic properties confirm
a charge density wave state at and above room temperature with transition
temperatures TCDW = 284, 335, 366, and 394 K for DyNiC2, HoNiC2, ErNiC2, and
TmNiC2, respectively. The Peierls temperature TCDW scales linearly with the
unit cell volume. A similar linear dependence has been observed for the
temperature of the lock-in transition T1 as well. Beyond the intersection point
of the trend lines, the lock-in transition is no longer observed. In this Rapid
Communication we demonstrate an extended phase diagram for the RNiC2 family.
