Maccaffertium is a Latinized version of the name of the world-renowned mayfly systematist, W. Patrick McCafferty. And, mediopunctatum is constructed from roots of medi- meaning middle, and punct- meaning point, so I assume this species has some distinctive feature midpoint in its anatomy. Assuming my logic is valid, perhaps someone else can tell you what the feature is.
The distribution of this species is confined to the states and provinces lying east of the N. American continental divide.
OK....... I understood the Maccaffertium, but didn't get the 'mediopunctatum' ending. I had two years of German, but no Latin.
This one has a mark down the center of its back( dorsal), maybe that has some relevenance. I don't recall that particular marking on my specimens, but they have those distinctive markings on the belly(ventral side). I find those markings very interesting.
Flyfishing is a state of mind! .............. Q.g.