Ocunautilus Korn & Hairapetian, 2025, gen. nov.

Genus Ocunautilus gen. nov. urn:lsid:zoobank.org:act: 1E0C7C57-E989-44E6-998D-730ECB2C672E New genus A – Korn 2025: 43. — Korn & Ghaderi 2025: 28. Type species Ocunautilus diplodocus gen. et sp. nov. Diagnosis Genus of the family Ocunautilidae fam. nov. with a subinvolute conch. Extremely to extraordinarily high coiling rate; whorl profile inverted trapezoidal, weakly compressed or weakly depressed with concave or flat venter and flattened, convergent flanks. Sculpture in the adult stage absent; in the juvenile stage sometimes with short ribs on the flank. Suture line with a shallow to deep V-shaped external lobe and a broadly rounded lateral lobe. Etymology From Greek ‘ὀξύς’=‘sharp’ and ‘ναυτίλος’; because of the angular ventrolateral shoulder. Included species Central Iran (this paper): Ocunautilus diplodocus gen. et sp. nov., Wuchiapingian; Ocunautilus coelodesmus gen. et sp. nov., Wuchiapingian; Ocunautilus tachytrephus gen. et sp. nov., Wuchiapingian. Remarks Ocunautilus gen. nov. can hardly be confused with any other genus of Late Permian nautilids because of its very characteristic conch shape. The rather sharp umbilical margin, the flattened and rapidly converging flanks, the angular, skid-like ventrolateral shoulder and the more or less clearly concave venter allow a clear separation. Pseudotitanoceras is similar to Ocunautilus, but this genus is distinguished by the presence of tubercles on the ventrolateral shoulder. Shimansky (1965) mentioned that among his P. armeniacum material there were also specimens without ventrolateral tubercles. Perhaps these do belong to Ocunautilus rather than Pseudotitanoceras.