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 Cyclolituites lynceus Holm, 1891 Figs 73–74 Cyclolituites Lynceus Holm, 1891: 33 , pl. 1 figs 8–9. Cyclolituites lynceus – Sweet 1958: 21 . — Neben & Krueger 1971 : pl. 32 figs 17–18. Cyclolituites lycnus – Flower 1975: 161 . Diagnosis Species of the genus Cyclolituites with conch diameters around 35 mm ; tight coiling with only the apertural part of the body chamber detached from preceding volutions; whorl expansion rate ca 3.00; whorl profile compressed (WWI = 0.70). Shell surface with fine growth lines and raised pairs of lirae up to 0.4 mm apart. Type material Not available for study; Holm (1891) did not specify a type but illustrated one specimen ( Holm 1891 : pl. 1 figs 8–9), which is reproduced here in Fig. 73C ; it comes from Lerkaka (Island of Öland, Sweden ), Folkeslunda Limestone (Upper Grey Orthoceratite Limestone, late Lasnamägi Regional Stage, late Darriwilian, Middle Ordovician). Material examined GERMANY • 1 spec. ; Brandenburg , Oderberg ; Ordovician ; Neben and Krueger Coll.; MB.C.30561 • 1 spec. ; Mecklenburg-Vorpommern , Boltenhagen (Gross Klütz Höved); Ordovician , Upper Grey Orthoceratite Limestone ; Neben and Krueger 1962 Coll.; MB.C.30562 . Description Specimen MB.C.30562 ( Fig. 73B ) is an almost complete, coiled conch with 32 mm diameter and consists nearly two tightly coiled whorls (WWI = 0.70; WER = 2.90; Fig. 74B–F ), of which only the second half of the last whorl is detached from the preceding. The umbilical window is 4 mm wide. 135 degrees of the last whorl belongs to the body chamber. An increasingly pronounced ridge is raised on the venter at the apertural end of the specimen. The shell ornament is preserved only in the inner whorls and consists of raised pairs of lirae (up to 0.4 mm in distance) and very fine growth lines. The aperture is partly preserved; it has a deep ventral sinus, elongated ventrolateral lappets and a rather shallow lateral sinus (dorsal edge of the aperture is not preserved). The chamber length varies between CLR = 0.20 and 0.30. Specimen MB.C.30561 ( Fig. 73A ) is an almost complete, coiled conch (dm = 37 mm , nearly two tightly coiled whorls with only the second half of the last whorl is detached; the umbilical window 5.3 mm wide; WWI = 0.71; WER = 3.10; Fig. 74A, C–F ); 135 degrees of the last whorl belong to the body chamber. The shell ornament is preserved only locally and consists of slightly irregularly spaced, raised lirae (up to 0.2 mm in distance) and very fine growth lines in between; the lirae leave imprints on the internal mould. The aperture is incomplete, only a fragment of one ventrolateral lappet is preserved. Remarks The two specimens under study are from the Neben & Krueger collection and one of them, MB.C.30562, was previously figured by Neben & Krueger (1971 : pl. 32 figs 17–18). Both specimens closely resemble Fig. 73. Cyclolituites lynceus Holm, 1891 . A . Specimen MB.C.30561 (Neben & Krueger Coll.) from Oderberg (Brandenburg). B . Specimen MB.C.30562 (Neben & Krueger 1962 Coll.) from Boltenhagen, Gross Klütz (Mecklenburg); previously figured by Neben & Krueger (1971 : pl. 32 figs 17–18). C . Reproduction of the illustration by Holm (1891 : pl. 1 figs 8–9). Scale bar units = 1 mm. Table 15. Siphuncular diameter ratio (SDR) and siphuncular distance ratio (SPR) at their corresponding whorl height in specimens of Cyclolituites Remelé, 1886 .

taxon	catalogue nr	wh	SDR	wh	SPR
C. applanatus	MB.C.11671	6.0	0.25	6.0	0.08
C. lynceus	MB.C.30561	11.2	0.41	11.2	0.09

the lectotype of Cyclolituites lynceus described by Holm (1891 : pl. 1 figs 8–9) and are thus confidently assigned to this species. Only specimen MB.C.30561 is slightly more compressed. In contrast to Cyclolituites applanatus , the species C. lynceus has a larger diameter of the conch (ca 35 mm ), a more compressed whorl profile (WWI = 0.70), a higher whorl expansion rate (WER ca 3.00) and a finer ornament. Cyclolituites lynnensis is smaller (conch diameter around 28 mm ) than C. lynceus and has a coarser ornament. Cyclolituites kjerulfi differs from the other species of Cyclolituites in the smaller in diameter ( 20 mm ); it uncoils much earlier (almost the whole last whorl is detached), has a narrower umbilical window and a much higher coiling rate (WER = 4.00–5.00). Geographic and stratigraphic occurrence Sweden (in situ) and northern Germany (in erratics within Pleistocene gravels); late Lasnamägi Regional Stage (late Darriwilian, Middle Ordovician).