Sunday, April 10, 2016
Fairly common -- but what a beautiful photo: Maccaffertium modestum
I'm still struck by Steven Beaty's comment on this flatheaded species -- "Most common [Maccaffertium] species in NC." ("The Ephemeroptera of North Carolina," version 3.3, p. 20) This is only the third M. modestum nymph that I've seen, and one of the others was in the same stream as this one-- Buck Mt. Creek. Of course, Beaty is talking about the whole state --I work in a much smaller area.
I won't review the ID details for this species. However, the ventral pattern is one of the keys --
the pair of dark, oblique, lateral stripes on segment 9, the two large anteromedial dark spots on segment 8, and the pairs of small anteromedial dark spots on the preceding segments. This matches the ventral pattern of Maccaffertium modestum in Fig. 68 in McCafferty and Bednarik's "Biosystematic Revision of the Genus Stenonema (Ephemeroptera: Heptageniidae), p. 68. Their detailed description of the M. modestum nymph can be found on p. 30 of the same monograph.
The only other insect of interest that I picked up this morning was one of the variant forms of Isoperla orata. More on that species when I report on insects up at the Rapidan River.