Note
Four species and one variety of marine diatoms belonging to Hustedt's groups Lanceolatae and Undulatae of the
genus Mastogloia were studied using transmitted light and scanning electron microscopy. Internal and external valve
structure is described for M. elegans Lewis, M. lineata Cl. et Grove, M. corsicana Grun. in Cl. et Moll. and M. rimosa
Cl. The rather simple valve structures of M. elegans and M. lineata contrast the more complex structures observed in
M. corsicana and M. rimosa. These differences were discerned using a comparative SEM and TLM technique. Subspecific
variations in M. lineata are discussed based on this SEM/TLM technique. A description is included for a new
variety, M. corsicana var. johnsonii.