Porellus

A porellus is a small pore in a valve. The plural is porelli. Groups of closely packed porelli occur in ocelli, pseudocelli and apical porefields.

Ross, R. and Sims, P. (1972) The fine structure of the frustule in centric diatoms: a suggested terminology British Phycological Journal 7: 139-163
Round, F.E., Crawford, R.M. and Mann, D.G. (1990) The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.