Trocholites splendor 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 splendor

description: Trocholites splendor sp. nov.
urn:lsid:zoobank.org:act: F1186D76-F91F-4FA4-B804-E73305EE1E11
Fig. 22; Table 13
Diagnosis
Species of the genus Trocholites with an adult conch diameter of 50 mm. Conch in the last whorl thickly discoidal (CWI ~ 0.50) and subevolute (UWI ~ 0.35). Whorl profile weakly depressed (WWI ~ 1.35). Whorl width and whorl height slightly increasing in last quarter volution. Shell ornament with sharp lirae with fine growth lines on outer whorl; inner whorls with thin ribs or thickened lirae.
Etymology
From the Latin ‘ splendor ’ (nomen), referring to the splendid ornament in the juvenile whorls in the holotype.
Type material
Holotype
POLAND – West Pomerania • Ustronie Morskie; probably Lasnamägi Regional Stage; Müldner Coll.; illustrated in Fig. 22; MB.C. 32175.
Description
Holotype MB.C.32175 (Fig. 22) is a conch with 49 mm diameter and with 3.5 preserved volutions, the last of which is largely preserved as an internal mould. A little more than half of the last whorl belongs to the body chamber; at a short distance from the aperture, the internal mould possesses a conspicuous, thick ridge with a sinus-like ventral extension. The conch is thickly discoidal (CWI decreases from 0.57 to 0.50 in the last quarter of the last whorl) and subevolute (UWI = 0.36); the whorl profile is weakly depressed (WWI decreases from 1.52 to 1.34 in the last quarter whorl). The shell ornament is best preserved in inner whorls, where it consists of thin ribs or thickened lirae. Sharp lirae with fine growth lines are locally preserved in outer whorl; the ornament elements are not visible on the surface of the internal mould. The length of the phragmocone chambers can be measured in the first 2.5 whorls; the chambers are very long in the earliest half a whorl (RCL = 0.81) and then become significantly shorter to RCL = 0.44. At the end of the phragmocone, the RCL is only about 0.20. The conspicuous thickening or ridge near the aperture of the terminal body chamber is interpreted as a growth anomaly.
Remarks
The holotype of Trocholites splendor sp. nov. is closely similar to some specimens of T. hospes, but it possesses thin ribs or thickened lirae on the surface of inner whorls, instead of only fine lirae in T. hospes. The shell ornament alone may not be a reliable character to form a basis for species distinction; however, the conch of T. splendor is more slender (CWI = 0.50 at dm = 49 mm) and less depressed (WWI = 1.34 at dm = 49 mm) than in specimens of T. hospes (Fig. 12).
The last whorl in the holotype of Trocholites kadakaensis sp. nov. differs in being more evolute (UWI ~ 0.46 vs 0.35), more depressed (WWI ~ 1.80 vs 1.35) and decreasing instead of increasing whorl width and whorl height of the terminal body chamber.
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 45-46, DOI: 10.5852/ejt.2025.982.2843, http://zenodo.org/record/15096341