Published online by Cambridge University Press: 31 May 2012
Descriptions and figures of five undescribed species are presented: Lachlania talea, L. iops, Epeorus (Iron) packeri, Rhithrogena notialis, and Heptagenia bella. Heptagenia mexicana Ulmer is tentatively transferred to the genus Stenonema, the nymphal stage is described for Isonychia sicca manca Eaton and Homoeoneuria salviniae Eaton, and new collection records extend the known distributional range of Dactylobaetis mexicanus Traver & Edmunds, D. musseri Traver & Edmunds, D. zenobia Traver & Edmunds, Isonychia sicca manca, Homoeoneuria salviniae, Epeorus (Iron) metlacensis Traver, and Stenonema mexicana.