Hi dc,
Welcome to the list.
Yes there is a 48 hole Rohloff hub however it is not in general sale. The 48 hole version is only available when buying a Rohloff equipped Thorn Tandem. It is laced in a Crows foot pattern.
It is worth noting that a 32 spoke Rohloff Wheel is MUCH stronger than a normal 32 spoke wheel. This is due to the zero dish required. (The larger than normal flange also helps.)