Strandoceras muhvi, Kröger, 2025

Strandoceras muhvi sp. nov.

urn:lsid:zoobank.org:act:06217430-05D8-4FDB-829D-06E6E44D3E05

Figs 41C View Fig , 42B View Fig , 44A View Fig

Diagnosis

Short Strandoceras with angle of expansion of up to ca 40°; conch cross section elliptically compressed; maximum conch height ca 65 mm; mature body chamber ca 70 mm long, slightly curved and contracted; ornamented with fine transverse lirae and / or growth bands.

Etymology

Refers to Muhv, a small troll in Eno Raud’s (1928–1996) children-book series “Naksitrallid”.

Type material

Holotype

ESTONIA • Kohila quarry ; Kõrgessaare Formation , Vormsi Regional Stage; TUG 42-432 .

Paratypes

ESTONIA • 1 spec.; Vormsi Island, Saxby shore ; Kõrgessaare Formation , Vormsi Regional Stage; TUG 939-58 • 1 spec.; same data as for preceding; GIT 878-27 View Materials .

Description

The most complete specimen is TUG 42-432 ( Fig. 41C View Fig ), which preserves parts of the phragmocone of the adult body chamber, and part of the outer shell. The conch surface is poorly preserved. Near the peristome, traces of transverse lirae or growth bands occur, which are ca 2 mm apart. The complete conch cross section is only preserved at the adapical end. There, the conch height and width are 29 mm and 27 mm, respectively (CHI = 1.07) and it is rounded elliptical in shape. At the base of the body chamber, the conch width can be reconstructed. There, the height and width are 67 mm and 54 mm, respectively (CHI = 1.25). In lateral view, the antisiphuncular margin is convex throughout. The prosiphuncular conch margin is only preserved in the phragmocone, which is concave throughout but with a lower curvature than the antisiphuncular conch margin, resulting in an inflated conch shape with a maximum conch height of ca 65 mm reached at ca 60 mm from the peristome. The complete length of the body chamber is ca 70 mm (RBL = 1.04). The phragmocone expands with an angle of 14°–41° with a maximum reached at conch heights of 41–50 mm (see supplementary data 1 for measurements). The sutures are straight and directly transverse and shallow and narrow, but distinct saddles occur on the prosiphuncular side. Throughout the preserved part of the phragmocone, the sutures are 5–7 mm apart (RCL: 0.12–0.17).

Details of the siphuncle and septal necks are preserved in specimen TUG 939-58 ( Fig. 44A View Fig ).The siphuncle is marginal in position, with a wide septal foramen (ca 9 mm) where the conch height is ca 50 mm (RSH = 0.18). The maximum width of the siphuncle is 15 mm where the chamber length is 4 mm (RSS = 1.7, SCR = 3.75). Thick endosiphuncular bullettes occur. The septal necks are cyrtochoanitic.

Remarks

This species of Strandoceras is unique to the genus regarding its high angle of expansion. S. schmidti ( Teichert, 1930) differs in having a less expanded conch and a smaller adult size (see below).