Heterotopic position

Heterotopic position applies specifically to the position of the fultoportulae of some concentrically undulate species of Stephanodiscus, such as S. aegyptiacus.

Fultoportulae on the valve face in these species have a heterotopic position in relation to each other because they reside in the central area of the convex valve and in the marginal area of the concave valve. In Greek, heterotopic means different place.

See the contrasting term, isotopic position.

Citations

Håkansson, H. and Meyer, B. (1994) A comparative study of species in the Stephanodiscus niagarae-complex and a description of S. heterostylus sp. nov. Diatom Research 9(1): 65-85

Publication Link: 10.1080/0269249X.1994.9705288
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.

Heterotopic — Diagram of two valves of *Stephanodiscus* in girdle view. The concave valve has marginal fultoportulae (red arrow). The convex valve has central fultoportulae (black arrow).