Don, this information is fascinating to me. All of the fly-fishing authors that delved into the entomology/taxonomy of Eastern mayflies for more than half a century have attributed the earliest emergence of Paraleptophlebia to adoptiva and describe mollis as one of the summer species. (They have also described mollis as one of the species that displays the "Jenny Spinner" coloration in the male imago, and adoptiva as one that has the solid dark brown color in the abdomen of the male imago.). I know that taxonomic misidentification and entomological misinformation is frequently passed from one fly-fishing author to the next until someone corrects it, but can you tell me more about how this confusion might have happened?

your comments on this subject, this year I paid particular attention to the mollis/adoptiva identifications during this past season. In the White Mountain National Forest rivers (our collecting focus this year), mollis was clearly by far the most common, dominant in the spring and into early summer. P. adoptiva was much less common, and only was present in the mid-summer. Identifications are based on larval characters/key in Needham, Traver & Hsu. Since the color patterns of the male imagos are so different (again from NT&Hsu), I can only suggest that these species were confused with others by fishermen.

The only person who had previously published a comprehensive review of life cyles of North American mayflies is the paper by Clifford, H.F. 1982. Life cycles of mayflies (Ephemeroptera), with special reference to voltinism. Quaestiones Entomologicae 18: 15-90. He listed both of these Paraleps as being winter univoltine (developing during the winter and emerging in the spring). In New Hampshire we found this to be true for adoptiva in our NH southern/warmer rivers (not quite the same as a Southern warm river), but they were a summer univoltine group in our northern colder streams/rivers (such as the Androscoggin where Tom collects). Mollis pretty much just emerges in the spring. In terms of abundance mollis is much more common in early season.
Of course the way to be sure with the larvae is to pull the mandibles out, but with experience you can tell them apart by looking at the mandibles in place with a microscope. P. mollis is a darker brown while adoptiva is a lighter brown. I just happened to have my copy of Needham, Traver & Hsu with me tonight (fussing with Leucrocuta adult identifications - tail time), and a quick check indicates that they characterize mollis larvae as dark brown and adoptiva as light brown. I suppose this could have been reversed by some later worker, but I am unaware of such a paper.
As usual, nothing resolves the question better than having the specimen in hand, but once the gills get knocked off my enthusiasm for identification of Paraleps disappears.

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