Epitainoceras lutense, Korn & Hairapetian, 2025

Epitainoceras lutense gen. et sp. nov.

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Fig. 24 View Fig ; Table 18 View Table 18

Diagnosis

Species of Epitainoceras gen. nov. with thickly discoidal, subinvolute conch (ww/dm ~ 0.55; uw/dm ~0.25) and weakly depressed whorl profile (ww/wh ~ 1.35) and very high coiling rate (WER ~ 2.35) at a conch diameter of 70 mm. Whorl profile polygonal with convergent flanks; venter tectiform with broad longitudinal midventral groove, flanks flattened, umbilical margin narrowly rounded. Sculpture with about 15 coarse ventrolateral, transversely elongated nodes per volution. Suture line with a small, rounded V-shaped external lobe, a broadly rounded, very shallow lateral lobe and a very shallow umbilical lobe.

Etymology

Named after the Lut desert (Central Iran), at which margin Baghuk Mountain is located.

Type material

Holotype

IRAN – Esfahan Province • Baghuk Mountain ; Hambast Formation, Araxoceras beds ( early Wuchiapingian); 2011; Korn et al. leg.; illustrated in Fig. 24 View Fig ; MB.C.32136 .

Paratype

IRAN – Esfahan Province • 1 specimen; same data as for holotype; MB.C.32137.

Description

Holotype MB.C.32136 is a corroded phragmocone specimen with a diameter of 75 mm ( Fig. 24B View Fig ). It allows the conch form, sculpture and suture line to be studied, but some conch dimensions can only be estimated. The conch is thickly discoidal and subinvolute (ww/dm ~0.55; uw/dm ~0.25) with a very high coiling rate (WER ~2.35). The whorl profile is slightly depressed (ww/wh ~ 1.35) and widest at the narrowly rounded umbilical margin. The venter possesses a moderately wide median groove; the ventrolateral shoulder is flattened and oblique, the flanks are weakly flattened and convergent and the umbilical margin is narrowly rounded ( Fig. 24A View Fig ).

Because of partial corrosion of the specimen, the sculpture cannot be examined in detail. It consists of two rows of nodes arranged on each side of the ventrolateral shoulder. The ventral row has nodes that are elongated in a lateral direction to form short ribs; the dorsal row consists of much weaker, circular nodes.

The suture line of the holotype has a shallow, broadly V-shaped external lobe, a low and broadly rounded, slightly asymmetric ventrolateral saddle, a shallow and very wide lateral lobe and a very shallow and small lobe on the umbilical wall ( Fig. 24C View Fig ). The last half volution has 15 phragmocone chambers (CLI =12).

Remarks

Epitainoceras lutense gen. et sp. nov. is similar to the Transcaucasian species E. dorsoplicatum comb. nov., but differs in having a much wider midventral groove and significantly larger ventral nodes. These nodes are laterally elongated in E. lutense , whereas they are simply conical in E. dorsoplicatum .