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 20271 10.5852/ejt.2022.799.1681 f53d5465-7162-45d6-892b-dfc0b8d99789 2118-9773 6341270 F52DBAB0-38C7-400F-9BA1-E2D8E6B19E7E Genus Angelinoceras Hyatt, 1894 Type species Lituites latus Angelin, 1880 ; subsequent designation by Sweet (1958) . Diagnosis Genus of the family Lituitidae with loosely coiled apical part of the conch, 30 to over 50 mm in diameter, and moderately expanded (ca 8°) sigmoidal backcoiled part. Whorl profile compressed throughout (WWI ~ 0.90 at the last whorl). Whorl expansion rate based on whorl height decreases during ontogeny from 3.00 to 2.00. Ornament with regularly spaced narrow annuli/raised lirae and finer lirae in between; annuli with deep ventral sinus, prominent ventrolateral projections, broad and asymmetric lateral sinuses, low dorsolateral projections, and a broad, nearly straight dorsal sinus subdivided, at least in the early stages, by a mid-dorsal projection. Ventral band with ventrolateral ridges may be present (after Sweet 1958 ; Furnish & Glenister 1964 ). Species included Only the type species. Remarks Fang et al. (2021) proposed, among others, to synonymise Angelinoceras with Lituites . The species of the two genera are indeed similar, essentially differing only in the conch size (coiled conch diameters in Angelinoceras may exceed 50 mm ). The herein studied material is, however, too incomplete in preservation to make a proper decision on this matter. The genus Angelinoceras consists only of the type species A. latum . This species is known from the middle Darriwilian strata of mainland Sweden and the Island of Öland, and also from erratics in Germany that derived from Darriwilian rocks of Baltoscandia. With its narrow stratigraphic range, A. latum is a stratigraphically significant taxon in Baltoscandia (e.g., Jaanusson & Mutvei 1953 ; Evans et al. 2014 ). Sweet (1958) described a probable second, stratigraphically younger species from the Ampyx Limestone of the Oslo-Asker district (Sandbian, early Late Ordovician). However, because of its fragmentary preservation, he assigned this specimen as Angelinoceras sp. Aceñolaza et al. (1977) reported Angelinoceras sp. from the San Juan Formation (Middle Ordovician) of the Argentine Precordillera, but that specimen differs in the geometry of the coiled conch part and has a lower expansion rate than characteristic representatives of Angelinoceras . In fact, based on the photograph provided by Aceñolaza et al. (1977 : pl. 1g ), it seems the specimen might actually belong to the family Estonioceratidae (order Tarphyceratida Flower, 1950 ), rather than the lituitids. Geographic and stratigraphic occurrence Norway and Sweden (in situ) and northern Germany and northern Poland (in erratics within Pleistocene gravels); Kunda to early Kukruse regional stages (Middle to early Late Ordovician).