Litoceras profilbekkenense Kröger & Pohle 2021, sp. nov.

• Main Authors: Kröger, Björn, Pohle, Alexander
• Format: Other/Unknown Material
• Language: unknown
• Published: 2021
• Subjects: Biodiversity; Taxonomy; Animalia; Mollusca; Cephalopoda; Tarphycerida; Trocholitidae; Litoceras; Litoceras profilbekkenense; Ny Friesland; Svalbard
• Online Access: https://zenodo.org/record/5795817; https://doi.org/10.5281/zenodo.5795817

Litoceras profilbekkenense sp. nov. urn:lsid:zoobank.org:act: 847E0904-7D05-46EF-81F3-EDA8A5F740A7 Figs 44B, 46–47 Diagnosis Litoceras with relatively slender, rapidly enlarging conch, with WER of 2.3; with reniform, depressed conch cross section and WWI of ca 1.3; ornamented with fine growth lines which run obliquely across the flanks and form broad hyponomic sinus; the siphuncle is relatively wide, ca 0.25 of apertural height, and at a distance of 0.25 of the corresponding apertural height from the dorsum. Etymology Referring to the Profilbekken River near the type locality. Type material Holotype Specimen FMNH-P30329; by monotypy. Type locality and horizon From Profilstranda section, Ny Friesland, Svalbard, PO 131, 128 m above base of Olenidsletta Member, Blackhillsian, Floian. Description This specimen is a tectonically distorted fragment of a phragmocone and parts of a ca 180° long body chamber with a conch diameter of 86 mm (Fig. 46). The base of the body chamber is at a conch diameter of 58 mm, where the conch has ca three volutions, a whorl height of 21 mm, an apertural height of 20 mm and a conch width of 28 mm. The WER of the conch at the base of the body chamber is 2.3 (see Fig. 47 for comparison). In cross section the whorls are reniform and show a very broad, almost flattened venter and rounded flanks. The conch surface is ornamented with pronounced growth lines and is otherwise smooth or with very low ribs. The septal perforation at the base of the body chamber is subcentrally positioned at a distance of ca 5 mm from the dorsal margin and has a diameter of ca 5 mm. The sutures are simple and directly transverse. Remarks This specimen falls within the range of variability of Trocholitoceras walcotti with respect to the IZR, WWI, and general conch cross section shape (see Fig 47); however, at a comparable conch size it has a much larger WER than T. walcotti and the siphuncle is wider and subcentrally positioned, as seen in Litoceras. Litoceras calciferum (Billings, 1865), L. insolens (Billings, ...