There have been a number of name changes recently among our native orchids, mostly changes of genus, that have shuffled many of the orchids back into older genera. Most of this taxonomic revision appears to have been done by Richard Bateman. Whether these names will stick remains to be seen, but at least for now these appear to be the current names.
First, Coeloglossum viride var. viridis, the Frog Orchis or Long-bracted Green Orchis, is now once again Dactylorhiza viridis var. virescens.
Third, all the Piperias, five species, have been moved back into the genus Platanthera, with Piperia candida changed to Platanthera ephemerantha.
Platanthera transversa and Platanthera elongata
Fourth, Malaxis monophyllos var. brachypoda seems now to be the accepted name for Malaxis brachypoda in spite of differences between that species and its Eurasian counterpart.
Fifth, the Small Round-leaf Orchis, Amerorchis rotundifolia, is now Galearis rotundifolia, a completely new genus for this species.
It is sometimes hard to keep up with the changes and to remember them, especially because the names seem to be in a continual state of flux and may be different again tomorrow. In any case, if you are looking for a particular species always check for synonyms.