Annulus (centric taxa)

Alveolus

 

Annulus (Geissleria)

In some centric diatoms, a hyaline ring separating the areolae in the valve center from the rest of the valve face. For example, the valve face of the genus Discostella has an annulus.


Citations

Houk, V., Klee, R. and Tanaka, H. (2014). Atlas of freshwater centric diatoms with a brief key and descriptions Part IV. Stephanodiscaceae B: Stephanodicsus, Cyclostephanos, Pliocaenicus, Hemistephanos, Stephanocostis, Mesodictyon & Spicaticribra. In: Poulícková, A. (ed.): Fottea 14 Supplement, 529 pp.