Extra V-Ray particle attributes
Per-particle attribute export
Additional V-Ray attributes can be added to particle shape nodes in Maya (both regular and nParticles).
This group allows you to control the number of segments for sphere particles. Note that currently, V-Ray does not instance the spheres, which may lead to a lot of RAM being used. It might be better to use an Instancer node in that case, which does proper instancing.
Sphere subdivisions - The number of segments for the spheres placed at each particle position.
This group allows to specify which per-particle attributes you want to be translated by V-Ray. These attributes are then available for use by the particleSampler node.