Consistent morphological and color differences, plus nymphal color patterns and setae, host preferences, and habits have been employed to recognize nine new species previously confused with Myzocallis bella (Walsh), M. walshii (Monell), and M. meridionalis Granovsky. All are apparently confined to North America and inhabit various species of red or black oaks. New diagnoses are presented for M. bella and M. walshii, which were inadequately originally described, and for M. meridionalis. Keys to nymphs and to alate viviparae are presented, and relationships among the species are considered. New are: M. melanocera, M. granovskyi, M. spinosa, M. elliotti, M. pepperi, M. frisoni, M. multisetis, M. longiunguis, and M. exultans.