  We have studied the angular dependent de Haas-van Alphen oscillations of
LaRu$_2$P$_2$ using magnetic torque in pulsed magnetic fields up to 60T. The
observed oscillation frequencies are in excellent agreement with the geometry
of the calculated Fermi surface. The temperature dependence of the oscillation
amplitudes reveals effective masses m*($\alpha$)=0.71 and m*($\beta$)=0.99
m$_e$, which are enhanced over the calculated band mass by $\lambda^{cyc}$ of
0.8. We find a similar enhancement $\lambda^{\gamma} \approx 1$ in comparing
the measured electronic specific heat ($\gamma = 11.5$ mJ/mol K$^2$) with the
total DOS from band structure calculations. Remarkably, very similar mass
enhancements have been reported in other pnictides LaFe$_2$P$_2$, LaFePO ($T_c
\approx 4K$), and LaRuPO, independent of whether they are superconducting or
not. This is contrary to the common perceptions that the normal state
quasi-particle renormalizations reflect the strength of the superconducting
paring mechanism and leads to new questions about pairing in isostructural and
isoelectronic Ru- and Fe-pnictide superconductors.
