What does it mean when only a single capacitance is specified for a variable capacitor?
A quick search through digikey shows many variable caps that are some value up-to 40pF. I would suspect something similar here in your example. They're most likely some value up-to the value they list. I would assume that the value they give is the maximum value that it can reach.

Here's some of the examples I looked at here.

I didn't see any capacitor ranges that started at 40pF and go up. I think the attribute of a variable capacitor that most circuit designers would be interested in is the maximum value. Then they would just assume that they can trim out to something less than that to tune to.