The early gephuroceratid ammonoids from the Roteisenstein Formation of Dillenburg (Cephalopoda, Ammonoidea) 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 Author Bockwinkel, Jürgen F7FE7EEA-B678-4FEE-879C-8C429F66BF3A Dechant-Fein-Strasse 22, 51375 Leverkusen, Germany. jbockwinkel@t-online.de text European Journal of Taxonomy 2022 2022-06-08 823 10 47 http://zoobank.org/d5ac626b-4a10-4cd9-b77b-6d7efe8d180e journal article 68733 10.5852/ejt.2022.823.1811 5cb7c978-e62d-4576-b32d-2469745af89a 2118-9773 6628057 D5AC626B-4A10-4CD9-B77B-6D7EFE8D180E Genus Darkaoceras Bockwinkel, Becker & Ebbighausen, 2009 Type species Timanites meridionalis Petter, 1959 (original designation). Diagnosis Genus of the family Taouzitidae with extremely discoidal, subinvolute to involute conch; venter subacute or acute in the adult stage. With single ventrolateral grooves. Suture line with wide external lobe, high median saddle, V-shaped E 2 lobe, V-shaped lateral lobe and shallow, rounded umbilical lobes. Suture line formula (E 2 E 1 E 2 ) L U 2 U 4 : U 3 U 1 I. Included species Timanites meridionalis Petter, 1959 , Ougarta; Timanites complanatum Petter, 1959 , Saoura Valley; Koenenites galeatus Matern, 1931 , Rhenish Mountains; Darkaoceras velox Bockwinkel, Becker & Ebbighausen, 2013 , Anti-Atlas. Remarks Darkaoceras (with subacute venter and four umbilical lobes) is morphologically intermediate between Mzerrebites (with narrowly rounded venter and three umbilical lobes) and Taouzites (with sharp venter and up to eight umbilical lobes).