Parasuttonium, Dumitrica, 2019

Dumitrica, Paulian, 2019, Cenozoic Spumellarian Radiolaria With Eccentric Microsphere, Acta Palaeontologica Romaniae 15 (1), pp. 39-60 : 47

Genus Parasuttonium nov. gen.

Type species. Parasuttonium taiwanense nov. sp.

Diagnosis. Test flat, three-armed, consisting of two parallel latticed plates with circular pores of rather regular size and radial or irregular disposition. Central structure consisting of a spherical and slightly eccentric latticed microsphere with 3 primary rays. Rays prolonged outside to form three latticed arms around them. Distal part of primary rays simple, not forked. Microsphere rather large, surrounded on the antapical side by a bilobate deuteroconcha.

Remarks. By its type species from the Quaternary of western Pacific around Taiwan, this genus is very close to Suttonium Schaaf by having a large latticed microsphere, a bilobed deuteroconcha on the antapical side of the microsphere and 3 radial bars originated in the microsphere: one axial and two lateral. It differs from Suttonium in not having the arms free but included in the skeletal disc, and in having the primary rays prolonged as spines outside the arms. In the three species of Suttonium the arms terminate into two curved opposite spines in planes perpendicular to the shell, one on each face, whereas this new genus has no such terminations. Moreover, in Suttonium the arms are hollow and the inner rays are connected with the wall of the arms only in perpendicular planes to the plain of the shell, whereas in P. taiwanense the spines are connected to the disc by branches in all directions.

It is strange the occurrence of Parasuttonium only in the Quaternary because its morphology is intermediate between that of Homunculodiscus (the disc-shaped skeleton) and Suttonium (three-rayed shell and a beginning of arms). With such a mixed characters, its FAD should have been somewhere in the middle or late Paleocene, before the FAD of Suttonium riedeli . Probably this enigma will be solved in future by another interpretation of its morphology or by finding much older species of this genus.

Etymology. From the Latin and Greek para – alongside, aside, closely related, and Suttonium .

Range and occurrence. Very rare in the Quaternary.