Diagnostic features
Pennate diatom, roughly boat-shaped in valve view, except for a central bulge that projects in the opposite direction to the curved cell ends. Bulges on both valves - which are identical - can be seen in girdle view, because the girdle is narrower on one side of the cell than the other (as in Epithemia, to which it is closely related). Raphes are located on the long edges of the valves (difficult to see). Chloroplasts golden-brown.
![[Rhopalodia], valve view, X640. Photo: Otago Regional Council & Manaaki Whenua Image](/assets/Tools-And-Resources/Identification/algae/rhopalodia640__ScaleWidthWzEwMjRd.jpg)
![[Rhopalodia], girdle view, X640. Photo: Otago Regional Council & Manaaki Whenua Image](/assets/Tools-And-Resources/Identification/algae/rhopalodia2__ScaleWidthWzEwMjRd.jpg)