Just in case you did not know yet, a new paper on _Pinguicula_ did hit the
newsstands:
Billie L. TURNER
"Two new gypsophilic species of _Pinguicula_ (Lentibulariaceae) from Nuevo
Leon, Mexico"
PHYTOLOGIA 76(1):69-72 (1994)
In this, _P.jorgehintonii_ and _P.hintoniorum_ are described as new
species. Both are very closely related to (rather sspp. or vars. than
independent spp.) _P.esseriana_. I fear the whole range of variability in
this complex is still not completely covered by names. I have seen
specimens which are even more different (from _P.esseriana_, _P.ehlersiae_,
_P.jaumavensis_, _P.jorgehintonii_, and _P.hintoniorum_) but I cannot
interpret these as really distinct at specific rank. However, as long as no
comprehensive synopsis of the whole complex can be presented we have
(preliminarily) to accept the existing names as valid.
Kind regards
Jan