Ken Tennessen's new Florida nymph key indicates that M. taeniolata are larger than M. illinoiensis.
"Abdomen width (max across segment 6) was greater in F-0 M. taeniolata (12.6–16.3 mm) than in F-0 M. alleghaniensis and M. illinoiensis (9.1–12.5 mm)."

This exuvia is 16 mm wide.

The key also indicates that M. taeniolata has "Metathoracic femur at least 12 mm long in F-0," and the metathoracic femur is much longer in this exuvia.