Trocholites glacialis, Aubrechtová & Korn, 2025

Trocholites glacialis sp. nov.

urn:lsid:zoobank.org:act:09A65391-6E39-4073-8C94-89570D4005DC

Fig. 19 View Fig ; Table 10 View 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 View Fig ; MB.C. 32173 .

Paratype

GERMANY – Berlin • 1 spec.; Schmargendorf ; Ordovician; 1906; Schmidt Coll.; illustrated in Fig. 19B View Fig ; MB.C. 11561 .

Description

Holotype MB.C.32173 ( Fig. 19A View Fig ) 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 View Fig ) 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.