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 Trilacinoceras discors ( Holm, 1891 ) Fig. 66A–B , Tables 12–13 Lituites discors Holm, 1891: 26 , pl. 1 figs 5–7, pl. 3 figs 3–4. Ancistroceras discors – Hyatt 1894: 508 . Trilacinoceras discors – Sweet 1958: 147 , pl. 13 figs 1, 4, 6, pl. 15 fig. 5, pl. 16 figs 1, 3, 7–8, 10. — Balashov 1962 : pl. 7 fig. 6. — Dzik 1984: 138 , text-fig. 55.12. Lituites discors – Dzik 1984: 137 , text-fig. 53b, e, pl. 40 figs 4–10. Diagnosis Species of the genus Trilacinoceras with coiled conch 18–33 mm in diameter; 2–3 coiling open or whorls contiguous. Whorl profile slightly compressed through ontogeny, commonly ventrally flattened; whorl expansion rate ca 2.70. Expansion angle of uncoiled part 3–6°; whorl height at maturity about 23 mm . Shell surface with annuli and/or lirae, typically fine in the coiled part (less than 1 mm apart) and coarser in the uncoiled part (up to ca 3 mm apart) of the conch. Mature aperture with very shallow and broad lateral sinuses and a short and wide ventral sinus (after Holm 1891 and Sweet 1958 ; modified). Type material Not available for study; Holm (1891) did not specify a type but he illustrated several specimens ( Holm 1891 : pl. 1 figs 5–7, pl. 3 figs 3–4); from Lerkaka (Island of Öland, Sweden ), uppermost Red Lituites Limestone (Lasnamägi Regional Stage, late Darriwilian, Middle Ordovician). Material examined GERMANY • 1 spec. ; Brandenburg , Niederfinow ; Ordovician , Upper Red Orthoceratite Limestone ; Neben and Krueger Coll.; MB.C.30552 • 1 spec. ; Brandenburg , Schwedt ; Ordovician , Upper Red Orthoceratite Limestone ; MB.C.30553 . POLAND • 1 spec. ; West Pomerania , Skowarcz (former Schönwarling), Gdańsk County ; Ordovician , Upper Red Orthoceratite Limestone ; MB.C.30554 • 2 specs ; West Pomerania , Ustronie Morskie (former Henkengahen); Ordovician , Upper Red Orthoceratite Limestone ; Krause Coll.; MB.C.11632.1 , MB.C.11632.3 . COUNTRY UNKNOWN • 1 spec. ; Ordovician , Upper Red Orthoceratite Limestone ; MB.C.30555 . Description Specimen MB.C.30552 ( Fig. 66A ) is a fragment of a coiled part (dm = 30 mm ; 1.3 openly coiled whorls but the whorls get in contact just before uncoiling) and the almost straight backcoiled part (length = 60 mm ; wh = 14 mm ; EA ~ 4°) of a conch. The whorl profile is compressed (WWI increases from 0.83–0.90 during the backcoiled stage). The shell ornament of the coiled part consists of rhythmically strengthened growth lines ( 0.10–0.15 mm apart), which ontogenetically transform into coarser lirae (up to 0.5 mm in distance); narrow annuli (ca 2.5 mm apart) appear after uncoiling. The ornament elements form a deep ventral sinus, a shallow to very shallow lateral sinus and a low dorsal projection; the ventral sinus is delineated by raised longitudinal lines in the coiled part, where the venter of the conch is slightly flattened. The ornament elements extend with a concavo-convex course; they are rectiradiate in the coiled part and prorsiradiate in the backcoiled part. Fig. 66. Species of Trilacinoceras Sweet, 1958 from the Upper Grey Orthoceratite Limestone. A . Trilacinoceras discors ( Holm, 1891 ) , specimen MB.C.30552 (Neben & Krueger Coll.) from Niederfinow(Brandenburg); previously figured by Neben&Krueger(1971 :pl. 21fig.1). B . Trilacinoceras discors ( Holm, 1891 ) , specimen MB.C.30553 from Schwedt (Brandenburg). C . Trilacinoceras knoefleri sp. nov. , holotype MB.C.11658 (Knöfler Coll.) from Teschendorf near Löwenberg (Brandenburg). D . Trilacinoceras knoefleri sp. nov. , paratype MB.C.30559 (Krueger Coll.) from Mukran (Sassnitz, Island of Rügen) (Mecklenburg-Vorpommern). Scale bar units = 1 mm. Specimen MB.C.30553 ( Fig. 66B ) is a fragment of a coiled conch, 25 mm in diameter. The shell ornament consists of growth lines, which ontogenetically transform into transverse, slightly asymmetric lirae ( 0.8 mm distance) with fine growth lines in between them. The ornament elements form a very shallow lateral sinus and a deep ventral sinus; a low subangular ridge is present ventrally. Remarks Trilacinoceras discors is most similar to Lituites toernquisti (described above), but differs in the possession of a three-lappeted aperture (instead of five-lappeted) and in being usually larger in conch dimensions ( Holm 1891 ; Sweet 1958 ). Geographic and stratigraphic occurrence Baltoscandia (in situ) and northern Germany and Poland (in erratics within Pleistocene gravels); late Aseri to Lasnamägi regional stages (late Darriwilian Middle Ordovician), possibly also early Kukruse Regional Stage (early Sandbian, early Late Ordovician). Trilacinoceras discors has a relatively wide stratigraphic and palaeogeographic range of occurrence. It is characteristic for the early Lasnamägian Lituites discors Zone of Baltoscandia ( Jaanusson & Mutvei 1953 ; Jaanusson 1960 ; Evans et al. 2014 ) but occurs also in the late Lasnamägian rocks of Germany (Pleistocene erratics) and possibly in the even younger, Uhakuan, strata of peri-Gondwana ( Sá & Gutiérrez-Marco 2009 ; Aubrechtová & Turek 2018 ).