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 Lituites baculus sp. nov. urn:lsid:zoobank.org:act: 4683F88A-1A93-436C-87E0-6A8E2996F9A8 Figs 54A , 55 , Tables 9–11 Diagnosis Species of the genus Lituites with a small coiled part (ca 21 mm in diameter); 1.5 tightly coiled volutions (only the last half volution slightly detached). Whorl expansion rate 2.70. Uncoiled part weakly curved, expansion angle 4°. Shell ornament with rectiradiate lirae in the coiled part and lirae (up to 0.5 mm distance) and annuli (up to 4 mm apart) in the uncoiled part. Ornament elements in the backcoiled part prorsiradiate with shallow lateral sinus. Etymology From the Latin ‘ baculus ’ (nomen) = ‘a stick’, referring to the shape of the holotype . Type material Holotype SWEDEN • Island of Öland , Gärdslösa ; Middle Ordovician ; Bottke Coll.; MB.C.29654 (illustrated in Fig. 54A ). Description Holotype MB.C. 29654 ( Fig. 54A ) consists of the complete coiled part (dm = 20.8 mm ; 1.5 tightly coiled volutions, of which the last half volution is slightly detached from the preceding; WER ah = 2.70; Fig. 55 ) and the weakly curved backcoiled and straight parts (length = 110 mm ; wh = 15.6 mm ; EA ~ 4°). The whorl profile is compressed (WWI = 0.88). The initial chamber of the phragmocone is 0.46 mm in length and the whorl height at the first septum is 0.94 mm . The ornament is rather coarse and regular. In the coiled part, only transverse, rectiradiate lirae are visible (< 0.5 mm apart). In the backcoiled and straight part, coarse annuli are added and are up to 4 mm apart with lirae of up to 0.5 mm distance; the ornament elements are prorsiradiate with a shallow lateral sinus. The chamber length ratio is ca 0.44 and increases during ontogeny. Remarks Lituites baculus sp. nov. is most similar to Lituites toernquisti because of the small overall size, the weak curvature of the backcoiled part and relatively low expansion angle of the backcoiled part. However, the new species has only 1.5 volutions, which expand rather rapidly (WER 2.70). The shell ornament is also different: L. baculus sp. nov. lacks annuli in the coiled conch part and in the backcoiled part, the ornament elements have prorsiradiate direction.