The specimen has three concentric spheres with a few (9-10) radial spines extending outwards – characteristic for Actinomma leptodermum (see http://www.radiolaria.org/species.htm?division=8&sp_id=8). However, it differs in the general morphology with its round second sphere, while the typical A. leptodermum has an irregular outline.
The outer (third) sphere differs from Actinomma leptodermum, having small to large-sized pores scattered about the surface, looking more like the sphere of a Collosphaerid.
Collected in a surface sediment sample (boxcore) in the Nansen Basin, Arctic Ocean.
Any comments on other Actinommidae species with a similar “collosphaerid” appearance?