Mismatch of plane of symmetry vs Gold Book's definition for a pseudochiral carbon
The Gold Book definition for a meso compound is 


  the achiral member(s) of a set of diastereoisomers which also includes one or more chiral members.   


So, a meso compound has chiral subsets. Here we would have three such subsets:


Leftmost carbon (2R)
The centermost (pseudochiral 3S) 
The rightmost (4S) carbon


Even though  the centermost carbon is pseudo chiral, the plane of symmetry still exists. The compound remains meso, achiral.   

Nomenclature is just for naming a compound.



The following two molecules are diastereomers, not enantiomers.