Initially I had difficulty counting antennal segments in the various (18) photos I snapped of this female. For a while, it seemed maybe there were 10 rather than 11 antennal segments...which would lead in the keys to R. epinomiae. But scrutinizing the full-size versions of all my images, I could ascertain there are 9 flabella...which together with the pedicel and scape give 11 antennal segments. So this indeed appears to be R. rex.

For more info, see remarks under 1st image of this series.