Valve morphology and taxonomy in the genus Stenopterobia (Bacillariophyceae)

Abstract

On the basis of type material and other samples the valve morphology of the type of Stenopterobia curvula (W. Smith) Krammer [syn. St. intermedia (Lewis) Brébisson] has been examined using light microscopy (LM) and scanning electron microscopy (SEM). The valve structure differs fundamentally from that of species in other genera of the Surirellaceae. The valves have a system of alveoli situated between transapical costae on the outside and the inside of the valves. The raphe canals run on very short wings and are connected to the inside of the valves by alar canals. Fibulae are not present. Stenopterobia delicatissima (Lewis) Brébisson, assigned to Surirella in the recent literature, has a similar valve structure as St. curvula, but the shape of its valve is not sigmoid.