Trocholites glacialis Aubrechtová & Korn, 2025, sp. nov.
Creators: name: Aubrechtová, Martina
name: Korn, Dieter
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Cephalopoda
Tarphyceratida
Trocholitidae
Trocholites
Trocholites glacialis

description: Trocholites glacialis sp. nov.
urn:lsid:zoobank.org:act: 09A65391-6E39-4073-8C94-89570D4005DC
Fig. 19; Table 10
Diagnosis
Species of the genus Trocholites with an adult conch diameter of 35 mm. Conch in the last whorl thickly discoidal (CWI ~ 0.52) and evolute (UWI ~ 0.45). Whorl profile moderately depressed (WWI ~ 1.80) with rounded flanks and venter. Whorl width and whorl height slightly increasing in last quarter volution. Shell ornament with irregularly thick, rursiradiate lirae, adaperturally raised; sharp lirae on inner whorls. Phragmocone chambers moderately long (RCL ~ 0.25). Suture line straight.
Etymology
From the Latin ‘ glacialis ʼ (adjective), meaning ‘glacial’ or ‘frozen’.
Type material
Holotype
POLAND – West Pomerania • Ustronie Morskie; Lasnamägi or Uhaku Regional Stage; Müldner Coll.; illustrated in Fig. 19A; MB.C. 32173.
Paratype
GERMANY – Berlin • 1 spec.; Schmargendorf; Ordovician; 1906; Schmidt Coll.; illustrated in Fig. 19B; MB.C. 11561.
Description
Holotype MB.C.32173 (Fig. 19A) is an incomplete specimen with a conch diameter of 35 mm and shows about 3.5 whorls. At maximum diameter, the conch is discoidal and evolute (CWI = 0.52; UWI = 0.45); the last whorl is moderately depressed (WWI = 1.81). Both whorl height and whorl width slowly gradually increase in the last preserved whorl. The ornament is only preserved in small areas and consists of irregularly coarse, rursiradiate lirae, which are raised near the aperture. Sharp lirae are present in the inner whorls. The length of the body chamber and shape and distance of suture lines cannot be determined.
Paratype MB.C.11561 (Fig. 19B) with nearly identical dimensions and ratios shows that the body chamber occupies a little more than half of the last volution. The phragmocone chambers are moderately long (RCL ~ 0.25); the suture line is nearly straight.
Remarks
Trocholites glacialis sp. nov. differs from T. contractus, T. freyjae sp. nov., T. baldri sp. nov., T. sp. 1 and T. sp. 3 in the increase of both whorl width and whorl height in the terminal body chamber.
Trocholites macrostoma has a greater adult conch diameter (42 vs 35 mm) and in the last whorl, the conch is more discoidal (CWI ~ 0.43 vs 0.52) and more evolute (UWI ~ 0.53 vs 0.45).
In the last whorl of Trocholites depressus, the conch is much more discoidal (CWI up to 0.40 vs ~ 0.52), the whorl profile is much less depressed (WWI 1.25–1.60 vs ~ 1.80) and the whorl height may slightly decrease adaperturally; phragmocone chambers tend to be longer (RCL = 0.30–0.40 vs 0.25) and the shell surface has ribs.
description: Published as part of Aubrechtová, Martina & Korn, Dieter, 2025, The coiled Middle Ordovician cephalopod genera Trocholites and Curtoceras (Tarphyceratida) from Baltoscandia and north-central Europe, pp. 1-78 in European Journal of Taxonomy 982 on pages 40-41, DOI: 10.5852/ejt.2025.982.2843, http://zenodo.org/record/15096341