genus A

Korn, Dieter & Ghaderi, Abbas, 2025, Late Permian nautiloids from Julfa (NW Iran), European Journal of Taxonomy 1018, pp. 1-113 : 28-29

New genus A Korn & Hairapetian (in press) sp.

Fig. 15 ; Table 7

Material examined

IRAN – West Azerbaijan • 1 specimen; Aras Valley ; Zal Member of the Ali Bashi Formation ( early Changhsingian); 2018; Ghaderi leg.; illustrated in Fig. 15 ; MB.C.32023 • 1 specimen; same data as for preceding; MB.C.32024 .

Description

Both specimens are fragmentary and only allow the geometry of the conch to be studied. Both have been sectioned and show that the inner whorls are largely crushed and partially dissolved. With a diameter of 72 mm, specimen MB.C.32023 is the smaller of the two ( Fig. 15 ). The reconstruction shows a thinly discoidal, subinvolute conch (ww/dm =0.43; uw/dm =0.19) with an inverted trapezoidal whorl profile. The venter is concave and bordered by a skid-like sharpened ventrolateral shoulder. The convergent flanks are almost flat with a slightly concave outer region; the umbilical margin is angular and the umbilical wall is flattened and ventrally directed. The surface of the shell appears smooth; the internal form shows no sculpture.

The second specimen MB.C.32024 has a conch diameter of approximately 120 mm and is more strongly deformed and dissolved. It agrees with the smaller specimen in terms of the sharp-edged shape of the umbilical margin.

Remarks

The two specimens from the Aras Valley appear to be very similar to the type species from central Iran in terms of the proportions of the venter. However, there seems to be a difference in the arrangement of the umbilical wall, which is vertical in the type species, but oriented towards the venter in the specimens from NW Iran.

Figures

Fig. 15. New genus A Korn & Hairapetian (in press) sp., specimen MB.C.32023 (Ghaderi 2018 Coll.) from the Zal Member of the Ali Bashi Formation at Aras Valley, polished cross section and reconstructed apertural view. Scale bar units =1 mm.

Tables

Table 7. Reconstructed conch dimensions (in mm) and ratios of the new genus A Korn & Hairapetian (in press) sp.

Nr.	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZR
MB.C.32023	71.5	30.5	37.0	13.5	27.0	0.43	0.82	0.19	2.58	0.27