This is a puzzling one to identify and I'm not sure about the species. The maxillary palp
is present and segmented, and the maxillary canines are not strongly serrate laterally. I think it's Ephemerella
, not Serratella
. The ventral
lamellae of the gills on abdominal segment 6 have a clear median notch with a depth at least half the length of the lamellae, which points toward a couple of uncommon species (most likely Ephemerella
alleni), but the abdominal tubercles
and coloration don't fit that species. To add to the confusion, none of the above species are expected to emerge in the fall, as far as I know. I'm going to call this one Ephemerella aurivillii
for now, but that's highly uncertain.