genus B hebes, Korn & Ghaderi, 2025

Korn, Dieter & Ghaderi, Abbas, 2025, Late Permian nautiloids from Julfa (NW Iran), European Journal of Taxonomy 1018, pp. 1-113 : 30-31

New genus B hebes sp. nov.

urn:lsid:zoobank.org:act:

Fig. 16 ; Table 8

Diagnosis

Species of Aifinautilus with thickly discoidal, subinvolute conch (ww/dm ~ 0.50; uw/dm ~ 0.20), equidimensional whorl profile (ww/wh ~1.00) and extremely high coiling rate (WER ~2.70) at a conch diameter of 55 mm. Whorl profile with weakly concave venter, broadly rounded ventrolateral shoulder, weakly convergent flanks, rounded umbilical wall and moderately deep imprint zone ( IZR ~ 0.25). Without sculpture. Suture line with very shallow external lobe and shallow lateral lobe.

Etymology

From the Latin ‘ hebes ’ (adj. m.)= ‘blunt’; because of the rounded ventrolateral shoulder and umbilical margin.

Type material

Holotype

IRAN – East Azerbaijan • Zal; Araxoceras Beds of the Julfa Formation ( early Wuchiapingian); 2018; Ghaderi leg.; illustrated in Fig. 16 ; MB.C.32024 .

Description

Holotype MB.C.32024 is an incomplete and laterally slightly distorted, fully chambered specimen with a conch diameter of 55 mm ( Fig. 16A ). The conch is thickly discoidal and subinvolute (ww/dm =0.52; uw/dm= 0.25) with an extremely high coiling rate (WER=2.71) and moderately wide whorl overlap ( IZR =0.25). The whorl profile is nearly equidimensional (ww/wh =0.98) with a weakly concave venter that is bordered by a broadly rounded ventrolateral shoulder; the flanks are broadly convex and weakly convergent ( Fig. 16B ). The umbilical margin is broadly rounded and the umbilical wall is steep and convex.

The suture line has a shallow external lobe, a narrowly rounded, very high ventrolateral saddle and a broadly rounded lateral lobe ( Fig. 16C ). The phragmocone has about ten chambers per half volution.

Remarks

Aifinautilus hebes sp. nov. differs from A. icanus in having a much more rounded umbilical margin and ventrolateral shoulder. In addition, the venter of A. icanus is much more deeply concave. The suture line of A. hebes has a much higher ventrolateral saddle than that of A. icanus .

The conch of A. hebes sp. nov. shows certain similarities with members of the family Tainoceratidae . The major difference, of course, is the presence of rows of nodes in the Tainoceratidae .

Figures

Fig. 16. Aifinautilus hebes sp. nov., holotype MB.C.32024 (Ghaderi 2018 Coll.) from the Araxoceras Beds of the Julfa Formation at Zal. A. Lateral view. B. Reconstruction of apertural view. C. Suture line at ww =55.0 mm, ww =28.5 mm, wh= 26.5 mm. Scale bar units =1 mm.

Tables

Table 8. Conch dimensions (in mm) and ratios of Aifinautilus hebes sp. nov.

Nr.	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZR
MB.C.32024	560	29.0	29.5	10.5	22.0	0.52	0.98	0.19	2.71	0.25