Trocholites baldri, Aubrechtová & Korn, 2025

Trocholites baldri sp. nov.

urn:lsid:zoobank.org:act:EE665BAD-AF26-4024-A9C5-8A558A5D376F

Fig. 17 View Fig ; Table 8 View Table 8

Diagnosis

Species of the genus Trocholites with an adult conch diameter of more than 30 mm. Conch in the last whorl thickly discoidal (CWI ~ 0.50) and evolute (UWI ~ 0.45) with moderately high coiling rate (WER ~ 1.75). Whorl profile moderately depressed (WWI ~ 1.80) with rounded flanks and venter, weakly embracing (IZR ~ 0.14). Whorl width and whorl height slightly decreasing in last quarter volution. Phragmocone chambers moderately long (RCL ~ 0.28). Suture line nearly straight.

Etymology

After Baldr, the Norse god of light, beauty and purity.

Type material

Holotype

GERMANY – Mecklenburg-Vorpommern • Göhren (Isle of Rügen); Lasnamägi Regional Stage ; illustrated in Fig. 17 View Fig ; MB.C. 32170 .

Description

Holotype MB.C.32170 ( Fig. 17 View Fig ) is a specimen with a conch diameter of 31 mm; the specimen is largely an internal mould with few shell remnants. The body chamber is preserved for a little more than half a volution in length and decreases slightly in width and height; the whorl width is reduced from 9.2 mm to 8.6 mm and the whorl height from 15.8 mm to 15.5 mm. This means that during the last half volution the conch becomes markedly narrower (CWI decreases from 0.61 to 0.50) and increasingly umbilicate (UWI increases from 0.37 to 0.46) with a terminal coiling rate of WER = 1.76. During this growth interval, the whorl profile is depressed (WWI decreases from 1.83 to 1.72) and weakly impressed dorsally (IZR = 0.12 at the maximum whorl height) with broadly rounded flanks and venter. Fine traces of transverse ornament elements are locally preserved on the shell surface. The phragmocone chambers are moderately long (RCL = 0.28) in the last volution; the suture line is almost straight.

Remarks

Trocholites baldri sp. nov. is most similar to the species T. macrostoma , T. freyjae sp. nov., T. glacialis sp. nov., T. sp. 1 and T. sp. 3 but differs in the decrease of both whorl width and whorl height of the terminal body chamber.

Compared to the specimens of Trocholites depressus , the holotype of T. baldri sp. nov. is stouter (CWI ~ 0.50 vs 0.35–0.40), expands more rapidly (WER ~ 1.75 vs 1.65) and the whorl profile is more depressed (WWI ~ 1.80 vs 1.25–1.60).

Rather similar in conch geometry to the holotype of T. baldri sp. nov. is the neotype of T. contractus ; however, in T. contractus , the decrease of body chamber width and height is much greater, the phragmocone chambers are slightly shorter and the suture line has a deeper ventral lobe.