  We report on the discovery of X-ray pulsations from the Be/X-ray system LS
992/RX J0812.4-3114 during an RXTE observation. From a timing analysis of the
source we obtained a barycentric pulse period of 31.8851 \pm 0.0004 s. The
pulse profile is highly structured and departs from a pure sinusoidal shape. It
shows a sharp dip that may indicate absorption by the accretion flow. The
energy spectrum from 3-30 keV can be fitted by a power-law model with an
exponential cut-off in accordance with other X-ray pulsars. The X-ray
luminosity is estimated to be $\sim 1.1 \times 10^{36} erg/s$ in the energy
range 3-30 keV, assuming a distance of $\sim 9 kpc$.
