Diagnostic features
Valves identical, neither possessing a raphe (genus is araphid). Wedge shaped in girdle view, often joined at valve faces to form fan-shaped colonies; club-shaped in valve view. Costae (thickened transverse silica bands) can be seen in valve view as strips across the valve, and in girdle view as obvious structures beneath the valve face. Chloroplasts golden-brown.
![[Meridion], Cardrona tributary, X400. Photo: Otago Regional Council & Manaaki Whenua Image](/assets/Tools-And-Resources/Identification/algae/meridion__ScaleWidthWzEwMjRd.jpg)
![[Meridion], X1600. Photo: Otago Regional Council & Manaaki Whenua Image](/assets/Tools-And-Resources/Identification/algae/meridion1600__ScaleWidthWzEwMjRd.jpg)