Taxonomic revision of selected Late Jurassic (Tithonian) calcareous nannofossils and the application of mobile mounting
Osman Varol and Andrew R. Bowman
In this study, the mobile mounting technique is used to investigate the morphologic characteristics of Polycostella senaria, Hexalithus geometricus, Nannoconus erbae and Nannoconus infans in different views, observed through rotation of the specimens in a mobile medium. We demonstrate that discrepancies in the published ranges are primarily caused by misunderstood taxonomic concepts representing these forms. Using this technique, we mapped and compared the side views of these forms to their equivalent plan views. The side/plan views of the following have also been mapped: Conusphaera maledicto, Conusphaera mexicana mexicana, Conusphaera rothii rothii, Paleomicula maltica, Sikoraea steinhaueri, and Trapezopentus dennei. We have established one new genus Sikoraea and ten new species Calcicalathina clipeus, Conusphaera maledicto, Cyclagelosphaera centrumelliptica, Cyclagelosphaera paucisegmenta, Ellipsagelosphaera clausa, Ellipsagelosphaera supergesta, Nannoconus magnadiscus, Paleomicula jacovidesii, Sikoraea steinhaueri, and Watznaueria moshkovitzii. In addition, we have introduced a new subspecies Conusphaera rothii minor and the following four new combinations Micrantholithus imbricatus, Polycostella parvistellatus, Trapezopentus dennei, and Trapezopentus valentinei.
Key words: Calcerous nannofossils, Tithonian, mobile mounting technique, new taxa.
Varol, O., Bowman, A.R., 2019. Taxonomic revision of selected Late Jurassic (Tithonian) calcareous nannofossils and the application of mobile mounting. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 291, 65-87.