I still hold to the "other" classification which maintains rhobocellatus as a sub-species of B. pentazona. The pentazona group tend to be longer thinner fish then tetrazona and partipentazona which have a deeper body shape.
I think the pentazona group is now...
B. pentazona pentazona
B. pentazona hexazona
B. pentazona foerschi
B. pentazona rhombocellatus
Possibly a tetrazona group or these could be discrete species...
B. tetrazona tetrazona
B. tetrazona partipentazona
... in the absence of genetic studies, it'll be a matter of opinion really.
I used to go with the B. pentazona partipentazona name, but the more specimens I see convince me that this is incorrect and that partipentazona is much closer to tetrazona than pentazona.
Whatever they are called, they are nice looking.