From May(fly) to September ...

When I went dragonfly hunting at Phu Rua NP last September, I came across a rather large mayfly. I have seen a number of mayflies before, but never one that was red. I think it looks great. I have no idea what species it is, other than it's a mayfly! Any help with ID?

Order: Ephemeroptera

Family: Unknown

Vernacular name: Unknown

Scientific name: Unknown