Ephemeroptera (mayfly) sub-imago (dun) : number of tails family trait? genus?

[Jim Speaker]

Good morning. I'm trying to find the answer to this question online, including searching here, with no luck:

Is the number of tails (2 or 3) on a mayfly at the sub-imago stage considered a trait that is consistent across an entire family within Ephemeroptera, or is there variation within the family and the number of tails can only be counted on being consistent at the Genus level?

Thanks in advance!

 

[Taxon]

Hi Jim,

The only completely reliable indicator regarding the number of tails (2 vs 3) of winged mayflies is that a given species has the same number of tails in its imaginal lifestage as it had in its subimaginal lifestage.

For example, all members of family Baetidae have 2 tails in their winged lifestages, whereas some members of family Ephemeridae (Hexagenia) have 2 tails in their winged lifestages, and some (Ephemera) have 3 tails in their winged lifestages.

However, genus is a mostly reliable indicator of regarding the number of tails (2 vs 3) of winged mayflies, were it not ror the fact that Ephoron females have 3 tails in their winged lifestages, whereas Ephoron males have 2 tails in their winged lifestages.

 

[Jim Speaker]

Thank you, Roger. I was afraid it was going to be a “not so simple” answer.

Much appreciated.