Tony-

Most Baetidae genera have hind wings, as does this Callibaetis male imago. It's just that they are extremely small, narrowly oblong, and point more toward the rear than upright. Most of the other Baetidae genera have hind wings that are more difficult to spot, especially in the imago lifestage. The mayfly families with only two wings are Caenidae and Leptohyphidae.

www.FlyfishingEntomology.com

Thanks for the sex, Roger. Is that why this guy doesn't have long cerci?

Peter-

Please forgive my not responding earlier, but I just noticed your question. Generally speaking, the imago has longer cerci that the subimago, but Callibaetis have reasonably long cerci in both winged life stages and both sexes. However, a mayfly's cerci are quite delicate, and can easily be broken off, as appears to be the case here.

The short incurved appendages at the end of the male abdomen are claspers, which are used (in addition to the fore legs) for holding the female during the coupling process. I suspect you already understand this, and am stating it for the benefit of others who may view this comment.