From your description of the crack, it sounds to me that the guitar has a solid(not a plywood) top, and if I understand, the crack starts at the soundhole and runs to the lower bout of the guitar--that would mean( if I understand)that the crack runs under the bridge area. If it is a solid top guitar, whatever the brand, it has in my estimation, potentially more value than a plywood instrument. Guitar wood "takes on" moisture as does --- the wood moves--when wood dries out, it shrinks across the grain, and that is probably what has caused the crack. I would determine if there is any other braces loose( small mirror and flashlight) or if the crack is causing any "buzzing" as the guitar is played. Once you let time pass, and the crack gets dirt in it, it will be much harder to get the crack to close-- and more noticable, if the crack is repaired later. Someone suggested repairing it with a plaster concoction and tinting it with tea--saying that the"repair" is reversable at a later date by cleaning out the "concoction" and proceding with a repair---I would not want that individual working on my guitar---My best advise would be to take the guitar to a good repair person and at minimum, get an estimate as to the cost. Unless the crack is completely closed before you procede with a superglue repair, the superglue will only worsen the appearance---done correctly however, this is one situation that CA glue would be O.K. to use in instrument repair-done correctly,the glue line can be sanded and polished out and in many cases made near invisable.