Taxonomy and ontogeny of the Lituitida (Cephalopoda) from Orthoceratite Limestone erratics (Middle Ordovician) Author Aubrechtová, Martina CAF4231-8787-4051-8D76-F983332517EE Institute of Geology and Palaeontology, Faculty of Science, Charles University Prague, Albertov 6, Prague, 12843, Czech Republic. & Institute of Geology, Czech Academy of Sciences, Rozvojová 269, Prague, 16500, Czech Republic. aubrech1@natur.cuni.cz & aubrechtova@gli.cas.cz Author Korn, Dieter 286CA4F3-7EBC-4AEF-A66A-B2508D001367 Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, 10115 Berlin, Germany. dieter.korn@mfn.berlin text European Journal of Taxonomy 2022 2022-03-08 799 1 1 108 http://dx.doi.org/10.5852/ejt.2022.799.1681 journal article 10.5852/ejt.2022.799.1681 f53d5465-7162-45d6-892b-dfc0b8d99789 2118-9773 6341270 F52DBAB0-38C7-400F-9BA1-E2D8E6B19E7E Rhynchorthoceras sp. Material examined GERMANY • 1 spec. ; Brandenburg , Eberswalde ; Ordovician , Upper Grey Orthoceratite Limestone ; MB.C.30510 • 1spec. ; Brandenburg , Gransee ( Ruppin ); Ordovician , Upper Grey Orthoceratite Limestone ; Kirchner Coll.; MB.C.11689 • 2 specs ; Brandenburg , Hohensaaten ; Ordovician , Upper Grey Orthoceratite Limestone ; Neben and Krueger Coll.; MB.C.30511 , MB.C.30512 • 2 specs ; Brandenburg , Niederfinow ; Ordovician , Upper Grey Orthoceratite Limestone ; MB.C.30513 , MB.C.30514 • 1 spec. ; Mecklenburg- Vorpommern , Dwasieden ( Island of Rügen ); Ordovician , Upper Grey Orthoceratite Limestone ; MfN excursion 1964 Coll.; MB.C.11711 • 1 spec. ; Mecklenburg-Vorpommern , Lebbin ; Ordovician ; Böhm 1906 Coll.; MB.C.11713 • 2 specs ; Mark ?; Ordovician ; MB.C.11705.1 , MB.C.11705.2 . POLAND • 1 spec. ; Silesia , Kunzendorf ; Ordovician ; MB.C.11712 • 1 spec. ; West Pomerania , Island of Chrząszczewska (former Gristow); Ordovician ; MB.C.11710 . SWEDEN • 1 spec. ; Island of Öland , Gärdslösa ; Ordovician ; Bottke Coll.; MB.C.29652 . Remarks In the collection under study, there are several specimens of orthoconic or weakly cyrtoconic lituitids, which have expansion angles between 10–14° ( Fig. 13A , Table 2 ), a circular whorl profile and a centrally located siphuncle with SDR between 0.12 and 0.14 ( Fig. 13B , Table 3 ). Thus, the specimens are assigned here to the genus Rhynchorthoceras . Since the shell surface in the above specimens is covered by conspicuously sinuous and asymmetric lirae, which form deep sinuses on the flanks and the venter, they should be assigned either to R. breynii from the Middle Ordovician erratics of northern Germany , or the other European species of Rhynchorthoceras with sinuous lirae, i.e., R. beyrichii (from late Darriwilian erratics of Poland ), R. helgoeyense Sweet, 1958 (from the late Middle or early Late Ordovician of Norway ) and R. zaddachi (from the Darriwilian erratics of the Kaliningrad Region , Russia ). Unfortunately, these species are rare and unequivocally known only from the type material, which has not been revised since the species descriptions and was not available for study herein. In addition, the ornament in the specimens in discussion is often incompletely or poorly preserved. Any species-level assignment of these specimens is thus avoided herein.