Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
See Platycentropus radiatus for details. It is the only species of this genus which is known to be important.
Where & when
In 132 records from GBIF, adults of this genus have mostly been collected during July (28%), June (26%), August (20%), October (8%), and September (6%).
In 36 records from GBIF, this genus has been collected at elevations ranging from 10 to 16404 ft, with an average (median) of 1125 ft.