Xitidae Pessagno, 1977b

Dumitrica, Paulian, Dieni, Iginio & Massari, Francesco, 2022, Valanginian Radiolarians Of Ne Sardinia (Italy) In The Frame Of The Weissert Event, Acta Palaeontologica Romaniae 18 (2), pp. 97-159 : 149

Family Xitidae Pessagno, 1977b

Type genus. Xitus Pessagno, 1977 b

Remarks. For generic assignation of the members of this family we follow Pessagno (1977b), with some critical remarks. This author erected the family Xitidae with three new genera: Crolanium Pessagno, 1977b (type species Crolanium triquetrum Pessagno 1977b ), Novixitus Pessagno (type species Novixitus mclaughlini Pessagno 1977b ) and Xitus Pessagno (type species Xitus plenus Pessagno 1977b) with well defined diagnoses and very good illustrations.

Crolanium was later (O’Dogherty, 1994) erroneously transferred to the family Parvicingulidae Pessagno 1977b and its type species synonymised, also erroneously in our opinion, with Stichocampe triangularis Aliev, 1968 , because the shape of the two species is not quite similar and also because it is very difficult to recognize in an old and simple drawing a species illustrated by electroscan microscopy. Concerning Novixitus , it was also synonymised, together with Pseudoxitus Wu and Pessagno in Wu, 1993, with the genus Xitus whose type species was synonymised with Dictyomitra spicularia Aliev, 1965 , that became Xitus spicularius (Aliev) . The reduction of the morphological diversity of this group to a single genus does not reflect the divergent evolution of these radiolarians during the Cretaceous.