Multiceratoidea, Mutvei, 2013

Kröger, Björn, 2025, The Lyckholm acme of cephalopods - Review of the late Katian (Vormsi-Pirgu regional stages) Ordovician cephalopods of Estonia, European Journal of Taxonomy 978, pp. 1-169 : 144-145

Multiceratoidea gen. et sp. indet. B

Fig. 39C

Material examined

ESTONIA • 1 spec.; Vormsi Island , Saxby shore; Kõrgessaare Formation, Vormsi Regional Stag; TUG 1743-37 .

Description

The specimen is a fragment of a curved adoral part of a mature body chamber. The complete length of the fragment is 63 mm. At the aperture, the conch is 50 mm high and slightly compressed, a shallow apertural sinus (hyponomic?) occurs at the side of the conch which in lateral profile forms the convex conch margin. Otherwise, the peristome was apparently straight, transverse. At its apical end, 47 mm from the aperture, the conch has a diameter of 55 mm and is circular in cross section. In lateral view, on the convex side of the conch curvature shallow, irregularly spaced ribs occur, which are ca 15 mm apart. The conch surface is ornamented with distinct growth lines.

Remarks

The available information about this species, i.e., the contracted curved body chamber, compressed conch cross section, hyponomic sinus on the convex side of the conch curvature suggest that it belongs to an unknown annulated multiceratoid. More complete material is needed for a definite determination.

Figures

Fig. 39. Hosholmoceras gen. nov., and an indeterminate fragment of a multiceratid of the Pirgu Regional Stage, Estonia. A–B, D. Hosholmoceras triangulatum sp. nov., holotype TUG 119-2, from Hosholm shore (tower), Vormsi Island. A. View of the antisiphuncular side. B. Lateral view. C. Multiceratoidea gen. et sp. indet. B, specimen TUG 1743-37, from Saxby shore, Vormsi Island, Vormsi Regional Stage, lateral view. D. Adapical view. E–G. Hosholmoceras ovalis gen et sp. nov., specimen GIT 840-252 (holotype), from Hosholm shore (tower), Vormsi Island. E–F. Specimen GIT 878-170. E. View of the prosiphuncular side. F. Lateral view. G. Specimen GIT 840-252 (holotype), lateral view.