Trocholites zaryensis 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 zaryensis

description: Trocholites zaryensis sp. nov.
urn:lsid:zoobank.org:act: DB8D668B-9A0C-4F0F-B279-31D4CDED0A17
Fig. 27; Table 18
Diagnosis
Species of the genus Trocholites with an adult conch diameter of about 36 mm. Conch in the last whorl thickly discoidal (CWI ~ 0.57) and subevolute (UWI ~ 0.42). Whorl profile moderately depressed (WWI ~ 1.82) with rounded flanks and slightly flattened venter. Whorl width slightly decreasing, whorl height slightly increasing in last quarter volution. Phragmocone chambers at 30 mm diameter moderately long (RCL ~ 0.30). Suture line nearly straight.
Etymology
From Żary (Poland), the locality of the holotype.
Type material
Holotype
POLAND • Żary; probably Darriwilian Stage; 1860; Kirchner Coll.; illustrated in Fig. 27; MB.C. 9718.
Description
Holotype MB.C.9718 (Fig. 27) is a conch of an individual in the terminal growth stage with 36 mm diameter. The last nearly three quarters of the conch belong to the body chamber, which is preserved as an internal mould. In the last quarter of a whorl, the conch shape changes from pachyconic to thickly discoidal (CWI decreases from 0.68 to 0.57) and stays subevolute (UWI ~ 0.42); the whorl profile is moderately depressed (WWI decreases from 1.96 to 1.82) with broadly rounded flanks and venter. The whorl width decreases slightly (from 21.5 mm to 20.6 mm), but the whorl height increases slightly (from 11.0 mm to 11.3 mm) near the aperture. The venter of the terminal body chamber becomes slightly flattened; the aperture possesses ventral and lateral flares. The shell is visible in the inner whorls; it is ornamented with rursiradiate lirae. The internal mould of the body chamber has indistinct annular ridges. The phragmocone chambers are moderately long (RCL = 0.30 at dm = 30 mm).
Remarks
Holotype MB.C.9718 of Trocholites zaryensis sp. nov. is very similar to holotype MB.C.11563 of T. kadakaensis sp. nov., which has a larger adult size (42 mm) and in which the terminal body chamber decreases in width as well as in height. Also, the last whorl in the holotype of T. kadakaensis is more discoidal (CWI ~ 0.48 vs 0.57).
Trocholites zaryensis sp. nov. differs from T. hospes in the shape of the body chamber and the much smaller conch with a fully adult diameter about 42 mm, in contrast to T. hospes with 50–60 mm. In addition, the whorl width in the last whorl slightly decreased in T. zaryensis.
Compared to the holotype of T. zaryensis sp. nov., the two specimens of T. vodickai sp. nov. are more discoidal (CWI ~ 0.40 vs 0.57) and slightly more widely evolute (UWI ~ 0.46 vs 0.42); the whorl profile is less depressed (WWI ~ 1.25–1.50 vs 1.82).
The holotype of Trocholites ruedemanni differs from the holotype of T. zaryensis sp. nov. by the slightly uncoiled terminal body chamber, presence of nodes and fine costae on the shell of last two whorls, much less depressed whorl profile in the last volution (WWI = 1.54 vs 1.96 at dm ~ 31 mm) and a narrower umbilicus (UWI = 0.32 vs 0.41 at dm ~ 31 mm).
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 53-54, DOI: 10.5852/ejt.2025.982.2843, http://zenodo.org/record/15096341