A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled.  They are especially large in this species.

Caption

A few (not all) of the abdominal tubercles (
A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled.  They are especially large in this species.
A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled. They are especially large in this species.
Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.
)
on this Ephemerella needhami nymph are circled. They are especially large in this species.
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