Micheal, It does match the description in Preissel's book. The short peaks, horizontal flowers, tightly wrapped calyx, orange red on the outside, yellow inside. Sure the leaves on the plant are larger and furrier than his description, but this can have to do with age/nutritional condition of the plants.
Also, you must remember that though Preissel's description of insignis is right, none of the pictures of "insignis" are really insignis. You have to take things in that book with a grain of salt.
I guess the next step for you is setting a seed pod. If the seeds have very little to no cork on them and are small, that should also help you lean toward pure vulc. The fact that it looks exactly like mine and the parent plant and the other pictures I posted on BGI of ones in the wild that Preissel said were vulcanicola's should help too. Seed pod shape can vary greatly, so I wouldn't count on that.
Of course there's always the argument that there is no such thing as a pure species Brugmansia. My friend even argued for fun once that there are only two species, Brugmansia brugmansia and Brugmansia sphaerocarpium, any differences between plants within those species are just variations or hybrids.
But I'm sticking with vulcanicola. It will be interesting to see if there is much difference from my seedlings from the north of Ecuador.