Recently in the IPA (International Phalaenopsis Alliance) Journal Second Quarter Vol.23(2) 2013 they had an article on speciosa and tetraspis with drawings and descriptions from when the 2 species were originally found. The article makes for very interesting reading.
You may want to get your hands on one if you can.
The author ends the article with, "There is strong opinions about the validity and identity of these species in the orchid community. While I have not seen specimens of both, examining the available drawings reveals that P. tetraspis and P. speciosa are certainly closely related if not conspecific.
If these two are the same species, the correct name would be P. tetraspis Rchb.f."
So in the end there is no real answer.
Hope you find this somewhat helpful
Judi