Early Tithonian entactinarian Radiolaria from the Solnhofen area (southern Germany). Part I

The article describes part of the Entactinaria radiolarians from a very rich and well-preserved radiolarian assemblage extracted from a lower Tithonian sample (Mue 22) collected from the Mühlheim Member of the Mörnsheim Formation of southern Germany. With a single exception (genus Odoghertites nov. gen.), all other Entactinaria described are of primitive type, that is their initial spicules are not differentiated into an apical and a basal group and are not connected by arches to form a heteropolar “microsphere”. They have been assigned to five families, four of which are new (Isometractiniidae, Triumbraculidae, Hollandocachoniidae, Odoghertitidae), 10 new genera (Isometractinia, Triumbraculum, Tardentactinia, Lententactinia, Hollandocachonia, Sphaerentofurca, Stylentofurca, Zuegelifurca, Spongentofurca, Odoghertites), and 19 new species. One of the new species comes from the lower Bajocian of Oregon. A new skeletal structural term, support structure, is introduced as a special type of connection between the primary spines and the macrosphere or cortical shell.