Serometacoceras cingulum, Korn & Ghaderi, 2025

Serometacoceras cingulum gen. et sp. nov.

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Fig. 21 View Fig

Pleuronautilus spec. indet. ex aff. Wynnei – von Arthaber 1900: 214, pl. 18 fig. 3.

Temnocheilus sp. indet. – Teichert & Kummel 1973: 419, pl. 3 figs 7–8.

Diagnosis

Species of Serometacoceras gen. nov. with subevolute conch and moderately depressed whorl profile (ww/dm ~ 1.75). Whorl profile broadly trapezoidal with gently divergent flanks; venter flattened, flanks slightly concave. Sculpture with about 15 prominent, blunt ventrolateral nodes per volution; the nodes are connected by blunt ribs across the flanks. Suture line with a broad and shallow external lobe and a usually slightly deeper, broadly rounded lateral lobe.

Etymology

From the Latin ‘ cingulum ’ (noun, n.) =‘a belt’; because of the belt-shaped conch.

Type material

Holotype

IRAN – West Azerbaijan • Zal; Araxoceras Beds of the Julfa Formation ( early Wuchiapingian); 2013; Korn et al. leg.; illustrated in Fig. 21 View Fig ; MB.C.32050 .

Description

The fragmentary holotype MB.C.32050 is a whorl segment of about 75 degrees ( Fig. 21A View Fig ). It has, at a whorl height of 20 mm, a moderately depressed trapezoidal whorl profile (ww/wh =1.73) ( Fig. 21B View Fig ). On the segment, there are three prominent ventrolateral nodes, which possess an elongation across the flanks and wedge out at the narrowly rounded umbilical margin. The suture line appears to be regularly undulated with shallow, broadly rounded lobes on venter and flanks, respectively; the internal lobe is broadly rounded and twice as deep as the external and lateral lobes ( Fig. 21C View Fig ). The septa are densely arranged in the fragment; they are spaced at intervals averaging about 10 degrees only.

Remarks

Although only one newly collected specimen is available, a new species is described because of the very distinctive conch shape. Serometacoceras cingulum gen. et sp. nov. has a similar sculpture to that of S. dorashamense gen. et comb. nov., but differs in that it has a much broader whorl profile (ww/wh ~ 1.75 in S. cingulum , but only ~ 1.25 in S. dorashamense ). The very broad whorl profile is also a distinguishing feature from other species of the genus.