Azarinautilus nahidae, Korn & Ghaderi, 2025

Azarinautilus nahidae gen. et sp. nov.

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Fig. 14 View Fig ; Table 6 View Table 6

Diagnosis

Species of Azarinautilus gen. nov. with thickly discoidal, subinvolute conch (ww/dm ~0.47; uw/dm ~0.27), weakly depressed whorl profile (ww/wh ~1.00–1.25) and very high to extremely high coiling rate (WER =2.30–2.60) at a conch diameter of 25–35 mm. Whorl profile weakly lyriform with strongly convergent, broadly convex flanks; venter deeply concave, umbilical margin broadly rounded. Sculpture with conical nodes in the midflank area. Suture line with rounded, broadly V-shaped external lobe and broadly rounded lateral lobe.

Etymology

Named after Nahideh Ghanizadeh Tabrizi, who assisted in the 2018 field session.

Type material

Holotype

IRAN – East Azerbaijan • Ali Bashi 4; Araxoceras Beds of the Julfa Formation ( early Wuchiapingian); 2010; Korn et al. leg.; illustrated in Fig. 14A–B View Fig ; MB.C.32019 .

Paratypes

IRAN – East Azerbaijan • 1 specimen; Ali Bashi 4; Araxoceras Beds of the Julfa Formation; 2018; Ghaderi leg.; illustrated in Fig. 14C–E View Fig ; MB.C.32020 • 2 specimens; Ali Bashi 4; Araxoceras Beds of the Julfa Formation; 2018; Ghaderi leg.; MB.C.32021 to MB.C.32022 .

Description

Holotype MB.C.32019 is a fragmentary internal mould specimen with a conch diameter of 30 mm ( Fig. 14A View Fig ). It is thickly discoidal and subinvolute (ww/dm= 0.47; uw/dm =0.27) with a whorl width equal to the whorl height. The lyriform whorl profile is widest at the broadly rounded umbilical margin, from where the flanks rapidly converge with a slightly concave incurve towards the sharp ventrolateral shoulder; the venter is concave ( Fig. 14B View Fig ). The sculpture consists of blunt conical nodes on the midflank, about eight of them occur in half a volution. Some of these nodes are slightly elongated in direction to the umbilicus. On the ventrolateral margin, there occur barely visible, faint tubercles.

Paratype MB.C.32020 is a fragment of a specimen with a conch diameter of 26 mm. It is fully chambered and preserved as an internal mould ( Fig. 14C View Fig ). The dimensions of the conch have been partially reconstructed, but the general morphology of the conch seems to correspond to the holotype. The ventrolateral shoulder is slightly elevated and forms skid-like ridges bordering the concave venter ( Fig. 14D View Fig ). The suture line forms a rather deep, bluntly rounded external lobe with nearly rectangularly arranged flanks, the ventrolateral saddle is narrowly rounded. The shape of the lateral lobe is generally broadly rounded, but when the septum lies near a conical node, it may show an inflexion ( Fig. 14E View Fig ).

The larger, unillustrated paratype MB.C.32021 shows, with a conch diameter of about 35 mm, an elongation of the midflank ribs; in this specimen these ribs extend almost across the entire flanks.

Remarks

Although there are only a few specimens available for examination, it can be assumed that this is a species with a small conch. No material is known from which the new species described here could be considered a possible juvenile form. The peculiar morphology with the deeply concave venter, the sharp ventrolateral keels and the conical nodes on the midflank easily distinguish the new species from all other Wuchiapingian species of Transcaucasia.