Add objects to center of mesh faces using particles Using Blender 2.79: I have a UV Sphere and would like to add objects to the center of the faces. 

Following this post it was not a problem to achieve this. But now I want only parts (rings) to be stocked with a specific object and other parts (rings) with other objects. I tried to use vertex groups for that.

The problems I am facing: 


I do not find a way to add objects to just 1 ring of faces.


My approach: If I want 2 or 3 rings coherently I highlight them (faces), apply them to a vertex group and then add a weight of 0 to the outermost edges. This does not work if I only want 1 ring. The objects will be distributed over 2 rings (above and underneath the vertex group edge). I also tried to add single particles to the desired faces in particle edit mode which worked fine but then they where not centered. 



I suppose the way I organize my vertex groups is not correct? Would you even use particles for that or recommend another approach? 

Anyone? :-)
Consider

Technique 01


Duplicate a ring mesh by itself with a particle system. Then move the ring to be coincident with the original sphere.  One sphere object for shape.  One ring object for particles.
For the duplicate ring, do not render emitter.  The particles remain.  Ensure the Particles per faces setting is value 1.  Set the value of number of particles.




Technique 02

See Duplication on faces.



Above the deleted faces of duplicator.



Above rendered image smoothed and using subdivision surface modifier.

Link 

Tapering a tentacle mesh with uniformly scaled suction discs

If your particles are static you might even use the Array Modifier.