Microptera and Guttata are the same species, Guttata is just the newer name for the species (like gymnetis caseyi being revised to gymnetis thula).
That is not quite right about the
guttata being the newer name. It is actually the older name, which is why it has the validity. The primary name has validity over secondary or teritiary names. Unless there was a significant error or such revision, the "first name published" has the validity, and all else are considered as "synonyms."
In case of
Gymnetis thula Ratcliffe, the population in the U.S. is separated from the population in Central (and/or Southern) America because of significant differences in morphological characters. Therefore, the U.S. population gets the name as a new species, and that's what happened with
G. thula.
They are two very different cases.
1.
guttata vs.
microptera = whether which name published first?
2.
caseyi vs. thula = U.S. population found out to be different species from southern population (
G. caseyi).
Since the U.S. population of
G. caseyi got new name as
G. thula, the holotypic specimen (as well as all other type specimens used in species description) are from southern countries, outside the U.S.