Pseudocellus

A pseudocellus is a porefield that lacks demarcation. Instead of a sharp boundary between areolae and porefield, the pores gradually decrease from typical areolae to smaller and smaller pores within the pseudocellus.

Pseudocelli are found in polar centric genera such as Hydrosera and Terpsinoë.

Porefield Types

apical porefield - separated from valve striae by a narrow hyaline area; occurs at valve apex of some araphid (e.g. Diatoma) and some raphid genera (e.g. Cymbella).

ocellulimbus - porefield set into the apex of a valve (e.g. Pseudostaurosira)

ocellus - porefield with a distinct hyaline rim (e.g. Pleurosira)

pseudocellus - porefield lacking demarcation and with pores decreasing in size (e.g. Terpsinoë)

See ocellulimbus, ocellus, and porefield for more detail.

Citations

Anonymous (1975) Proposals for standardization of diatom terminology and diagnoses Nova Hedwigia, Beihefte 53: 323-354
Ross, R., Cox, E.J., Karayeva, N.I., Mann, D.G., Paddock, T.B.B., Simonsen, R. and Sims, P.A. (1979) An amended terminology for the siliceous components of the diatom cell Nova Hedwigia, Beihefte 64: 513-533
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.

Hywhamp Ill 2013 132 1 — LM image of *Hydrosera whampoensis* with a pseudocellus at the apex of each narrow pole.