Azarinautilus phorminx, Korn & Hairapetian, 2025

Korn, Dieter & Hairapetian, Vachik, 2025, Late Permian nautiloids from Baghuk Mountain (Central Iran), European Journal of Taxonomy 1019, pp. 1-76 : 25-26

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.17259256

persistent identifier

https://treatment.plazi.org/id/03E487D4-FFC3-4919-FD91-5C8084BEFA11

treatment provided by

Plazi

scientific name

Azarinautilus phorminx
status

sp. nov.

Azarinautilus phorminx sp. nov.

urn:lsid:zoobank.org:act:

Fig. 14 View Fig ; Table 8 View Table 8

Diagnosis

Species of Azarinautilus with thickly discoidal, subevolute conch (ww/dm ~ 0.40; uw/dm ~ 0.32), equidimensional whorl profile (ww/wh ~ 1.00) and very high coiling rate (WER ~ 2.30) at a conch diameter of 45 mm. Whorl profile rounded lyriform with strongly convergent, broadly convex flanks; venter moderately concave, umbilical margin subangular. Whorl overlap small ( IZR ~0.15). Sculpture with short ribs in the midflank area. Suture line with a very shallow external lobe and a very shallow lateral lobe.

Etymology

From the Greek ‘φόρμιγξ’=the ancient Greek lyre; because of the whorl profile.

Type material

Holotype

IRAN – Esfahan Province • Baghuk Mountain section G; Hambast Formation, Paratirolites beds ( late Changhsingian), 2 m below top; 2012; Korn et al. leg.; illustrated in Fig. 14 View Fig ; MB.C.32121 .

Description

Holotype MB.C.32121 is a somewhat corroded internal mould with a diameter of 46 mm ( Fig. 14B View Fig ). About 135 degrees of the last whorl belong to the body chamber. The conch is thinly discoidal and subevolute (ww/dm=0.40; uw/dm=0.32) with a very high coiling rate (WER=2.32). The whorl profile is almost equidimensional (ww/wh = 0.99) and shows a narrow, slightly concave venter that is separated by a rounded ventrolateral shoulder from the convex flanks. The whorl profile is widest near the rounded umbilical margin; the flanks are strongly convergent. The umbilical margin is pronounced and subangular and the low umbilical wall is steep. The whorl overlap rate is small ( IZR ~ 0.15). The shape of the whorl profile changes significantly in the last volution. At the beginning it shows almost parallel flanks and a flattened venter with a shallow longitudinal depression ( Fig. 14A View Fig ). The sculpture also changes on the last volution. At the beginning there are only very fine riblets on the inner flank; these grade into rather strong, sharp ribs. They start directly at the umbilical margin and are directed forward. In the middle of the flank they become weaker and disappear completely. The suture line shows a very shallow, broadly rounded external lobes as well as two very shallow lobes on the flank ( Fig. 14C View Fig ). This course strongly depends on the shape of the respective whorl profile at the position of the septum. There are about 12 chambers in the last half volution of the phragmocone (CLI =15).

Remarks

Azarinautilus phorminx sp. nov. differs from A. nahidae from Julfa in the much less concave venter, the subangular umbilical margin and the slightly wider umbilicus (uw/dm> 0.30 in A. phorminx , but only 0.25 in A. nahidae ). The suture line of A. phorminx shows a very shallow external lobe, which is much deeper in A. nahidae .

Table 8. Conch dimensions (in mm) and ratios of Azarinautilus phorminx sp. nov. from Baghuk Mountain.

Nr. dm ww wh uw ah ww/dm ww/wh uw/dm WER IZR
MB.C.32121 46.0 18.5 18.6 14.7 15.8 0.40 0.99 0.32 2.32 0.15

Kingdom

Animalia

Phylum

Mollusca

Class

Cephalopoda

SubClass

Nautiloidea

Order

Nautilida

SubOrder

Domatoceratina

SuperFamily

Grypoceratoidea

Family

Domatoceratidae

Genus

Azarinautilus

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