That's a splined shouldered bolt. It's made to go into a mating splined socket by being tapped into place and then sucked the rest of the way in my the tightening of the nut.
The idea behind it is so that it will not rotate as the nut in being tighened onto it. Perhaps the location it is going to does not allow for a wrench to hold a conventional hex head bolt still while the nut is being tightened onto it.
The bolt in your picture also has a flat head with no hex flats; perhaps it's like that to facilitate being flush up against something.
I have some splined bolts on my car for attaching the lower shock mounts to the spindle; although, they are much bigger.