Ocunautilus diplodocus, Korn & Hairapetian, 2025

Korn, Dieter & Hairapetian, Vachik, 2025, Late Permian nautiloids from Baghuk Mountain (Central Iran), European Journal of Taxonomy 1019, pp. 1-76 : 16-17

publication ID

https://doi.org/10.5852/ejt.2025.1019.3071

publication LSID

lsid:zoobank.org:pub:E24EBF4A-9FE2-47E4-A656-E1698F88BB41

DOI

https://doi.org/10.5281/zenodo.17227678

persistent identifier

https://treatment.plazi.org/id/03E487D4-FFD4-4910-FDE8-5B1B8175FD00

treatment provided by

Plazi

scientific name

Ocunautilus diplodocus
status

gen. et sp. nov.

Ocunautilus diplodocus gen. et sp. nov.

urn:lsid:zoobank.org:act:

Fig. 8 View Fig ; Table 4 View Table 4

Diagnosis

Species of Ocunautilus gen. nov. with thinly discoidal, subinvolute conch (ww/dm ~0.42; uw/dm ~0.20), weakly compressed whorl profile (ww/wh ~ 0.85) and extremely high coiling rate (WER ~2.95) at a conch diameter of 100 mm. Whorl profile inverted trapezoidal with deeply concave venter, angular ventrolateral shoulder, flattened and weakly convergent flanks, angular umbilical margin and steep and weakly concave umbilical wall. Whorl overlap small ( IZR ~ 0.12). Without sculpture. Suture line with a very deep, rounded V-shaped external lobe, an angular ventrolateral saddle, a shallow and broadly rounded lateral lobe and a very small umbilical lobe.

Etymology

From the Greek ‘διπλόος’=‘double’ and ‘ὀξύς’=‘sharp’; because of the double-keeled venter.

Type material

Holotype

IRAN – Esfahan Province • Baghuk Mountain ; Hambast Formation, Araxoceras beds ( early Wuchiapingian); 2013; Korn et al. leg.; illustrated in Fig. 8 View Fig ; MB.C.32110 .

Paratypes

IRAN – Esfahan Province • 2 specimens; same data as for holotype; 2010; Korn et al. leg.; MB.C.32111, MB.C.32112.

Description

Holotype MB.C.32110 is a fragment showing slightly more than a quarter whorl of the phragmocone and a poorly preserved piece of the penultimate whorl ( Fig. 8A View Fig ). The fragment has a maximum whorl height of 51 mm; from this, a diameter of 105 mm can be reconstructed. On the basis of this calculated diameter, the conch parameters can be determined. The conch is thinly discoidal and subinvolute (ww/ dm ~ 0.42; uw/dm ~ 0.21) with an extremely high coiling rate (WER ~ 2.96). The whorl profile is weakly compressed (ww/wh= 0.87) with a deeply concave venter that is bordered by a sharp, skid-like ventrolateral shoulder; the flanks are flattened and convergent. Most conspicuous is the angular umbilical margin, which borders the weakly concave, incurved umbilical wall ( Fig. 8B View Fig ). The whorl overlap is small ( IZR =0.14). The specimen does not show any sculpture. The suture line is strongly influenced by the outline of the whorl profile; it is characteristic because of the narrow and deep, V-shaped external lobe, which is separated from the broadly rounded lateral lobe by a subangular ventrolateral saddle ( Fig. 8C View Fig ). The last quarter volution of the phragmocone consists of seven chambers (CLI = 13); there occurs weak septal approximation toward the aperture.

Remarks

Ocunautilus diplodocus gen. et sp. nov. differs from the other two species O. coelodesmus gen. et sp. nov. and O. tachytrephus gen. et sp. nov. from Baghuk Mountain by the much more deeply concave venter; accordingly, the external lobe of O. diplodocus is also much deeper and narrower.

MB

Universidade de Lisboa, Museu Bocage

Kingdom

Animalia

Phylum

Mollusca

Class

Cephalopoda

SubClass

Nautiloidea

Order

Nautilida

SubOrder

Domatoceratina

SuperFamily

Grypoceratoidea

Family

Domatoceratidae

Genus

Ocunautilus

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