Deckeroceras balticum Kröger, 2025, sp. nov.

Deckeroceras balticum sp. nov. urn:lsid:zoobank.org:act: 05BFB795-1743-407B-8866-5030650628D2 Fig. 36A Winnipegoceras sp. – Teichert 1930: 294, pl. 8 fig. 23. Diagnosis Deckeroceras with mature conch height of ca 65 mm, nearly circular to slightly compressed conch cross section at mature body chamber; mature body chamber strongly curved and contracted. Etymology Refers to type region. Type material Holotype ESTONIA • Vohilaid Island, Vohilaid shore (E): Adila Formation, Pirgu Regional Stage; GIT 878-227. Description The specimen is a fragment of a mature body chamber and five chambers of the phragmocone. The outer shell of the specimen is not preserved. At the base of the body chamber, the conch is ca 65 mm high. At the apical end of the specimen, 32 mm from the base of the body chamber, the conch height is 49 mm, and the conch cross section was nearly circular or slightly compressed. The angle of expansion of the phragmocone is ca 28°. The sutures are directly transverse and 8 mm apart where the conch height is 49 mm (RCL = 0.15). The siphuncle and the septal foramen are either not preserved or not visible. The body chamber is strongly curved and ca 65 mm long. In lateral view the convex side of the conch is much more strongly curved than the concave side, resulting in a relatively narrow mature aperture (height ca 40 mm). Remarks A specimen from Piirsalu, Estonia, figured and described in Teichert (1930), is identical in size and shape, and can be assigned to the same species, based on the knowledge of this more complete specimen, described herein. Comparison The two other species of this genus (D. adaense, D. clermontense Foerste 1935b, known from the type-region and from the Elgin Member of the Maquoketa Shale, Iowa, USA) have smaller adult sizes (maximum conch heights 40–50 mm), and in D. clermontense Foerste, 1935a the mature body chamber is less strongly curved.