The whorls of spines around the tail segments on this nymph had me thinking it was in the closely related Serratella genus for a while, but this close-up picture reveals the web of fine setae that sets the Ephemerella genus apart.  Ephemerella aurivillii Mayfly Nymph from Mongaup Creek in New York
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The whorls of spines around the tail segments on this nymph had me thinking it was in the closely related Serratella genus for a while, but this close-up picture reveals the web of fine setae (Seta: Little hairs on insects.) that sets the Ephemerella genus apart.
Ephemerella aurivillii Mayfly Nymph from Mongaup Creek in New York

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