My goodness! I believe you're reading words into my posts that I never put into my sentences. For instance, I never said, "bees of Apis species that nest in the open ALWAYS [emphasis mine] orient their dances horizontally." I know I did not throw the word "always" into my statement, simply because I knew that some individuals might "dance" on vertical planes or on planes at other angles. I would NOT say, either, that members of A. mellifera "always" dance on a vertical plane.
But bees of species that typically build exposed combs usually "dance" on a roughly horizontal plane. Bees of species (A. mellifera and A. cerana) that typically build comb in cavities usually "dance" on a roughly vertical plane. That much has been documented many, many times, and it's simply that -- nothing more said about the purpose or the reasons for the "dances," just that they occur and the orientation of these "dances" changes based on the exposure of the comb.
Similarly, I did not write that "A. mellifera & cerana are. . . unique in the ability to change from direction in relation to light to direction in relation to gravity." Instead, I wrote that the two species are "fairly" unique in their conversion from light to gravity. I don't know of any other species of Apis that shows a similar replacement, do you? Doesn't that make them unique in the genus?
Also, you've repeatedly said that beetles also switch from one to the other. I've looked, but I haven't been able to find similar behavior documented for beetles, particularly behavior in which individuals orient in relation to the position of the sun, then "replay" that orientation but substitute gravity for the position of the sun. Which beetles use this behavior, and in what sorts of circumstances?
Finally, please note that I did not say that the switch from sun to gravity was the explanation for the dance language, or that the behaviors you listed as explanations for the "dances" of bees were in fact evolutionary steps in the development of a dance language. I wrote that the series of behaviors have been hypothesised as possible evolutionary steps in the development of a "dance language." Hypothesised, not given as evidence. There is a difference.
But I digress. Now, how could bees originating from a wooden hive determine that a water meter (or a similar cavity of completely different consistency that their wooden cavity) would make a suitable hive? And, how would the scents brought back to a swarm on a scout that initially found a water meter differ from other "earth" scents in the area around the water meter?