Domatoceras convergens

Domatoceras convergens (Abich, 1878) Fig. 10 Nautilus convergens Abich, 1878: 17, pl. 3 fig. 2. Domatoceras convergens – Shimansky 1965a: 41, pl. 15 fig. 9. Diagnosis Species of Domatoceras with extremely discoidal, subevolute and weakly compressed, inverted trapezoidal whorl profile (ww/wh ~0.60) at a conch diameter of 75 mm. Whorl profile with flat, very narrow venter, subangular ventrolateral shoulder, convergent, flattened flanks and broadly rounded umbilical margin. Suture line with a very narrow and very shallow external lobe and a much larger and deeper, broadly rounded lateral lobe. Material examined IRAN – West Azerbaijan • 1 specimen; Aras Valley; Araxoceras Beds of the Julfa Formation (early Wuchiapingian); 2018; Ghaderi leg.; illustrated in Fig. 10; MB.C.32003 • 1 specimen; same data as for preceding; 2018; Ghaderi leg.; MB.C.32004. – East Azerbaijan • 1 specimen; Ali Bashi 4; Araxoceras Beds of the Julfa Formation (early Wuchiapingian); 2010; Korn et al. leg.; MB.C.32005. Description Specimen MB.C.32003 is, though fragmentarily preserved, suitable for identification as it shows some specific characters (Fig. 10A). It has a whorl height of 26 mm and a ww/wh ratio of 0.57. The venter is flat and bordered by an angular ventrolateral shoulder; the flanks are weakly convex and converge from the rounded umbilical margin (Fig. 10B). The suture line shows a small and very shallow external lobe and a very wide, broadly rounded lateral lobe (Fig. 10C). Remarks Abich (1878: 17, pl. 3 fig. 2) described and illustrated, as “ Nautilus convergens, nov. form.”, a fragment (less than a quarter of a volution) of an internal mould of 40 mm whorl height. From this, the conch shape can be reconstructed rather well. The inverted trapezoidal whorl profile is compressed (ww/wh =0.62) and very weakly inflected dorsally by the preceding whorl. It is widest near the umbilical margin. The flanks converge rather rapidly and are separated from the flattened venter by a subangular ventrolateral shoulder. There is a shallow longitudinal groove on the outer portion of the flank just adjacent to the ventrolateral shoulder. No ornament can be seen. The suture line shows a broad rounded lobe on the flank and a very shallow lobe on the venter.