Scanning electron micrographs are presented for 14 species of the North American alderfly Sialis: americana, arvalis, californica, contigua, cornuta, hamata, iola, joppa, mohri, nevadensis, occidens, rotunda, vagans, and velata. Male genitalic characters are described for use in species identification.
Whiting, Michael F.
"Scanning electron microscopic study of the male genitalia of the North American alderfly genus Sialis (Megaloptera: Sialidae),"
Great Basin Naturalist: Vol. 51
, Article 12.
Available at: http://scholarsarchive.byu.edu/gbn/vol51/iss4/12