The attached image shows a plant which is,
apparently, the true N. burkei, or so Charles
Clarke has told me after conferring with
Shigeo Kurata. The pitcher shown is still
quite young, and its peristome has not
yet assumed its customary ruddy hue.
Note that it is morphologically quite similar
to N. ventricosa, but the "waist" of the pitcher
is not as constricted as one finds in that case.
However, my personal opinion is that it is pretty
nearly indistinguishable from N. ventricosa.