Dzhulfites brevisellatus Korn & Hairapetian, 2021

Korn, Dieter, Hairapetian, Vachik, Ghaderi, Abbas, Leda, Lucyna, Schobben, Martin & Akbari, Amir, 2021, The Changhsingian (Late Permian) ammonoids from Baghuk Mountain (Central Iran), European Journal of Taxonomy 776, pp. 1-106 : 30-32

Dzhulfites brevisellatus Korn & Hairapetian sp. nov.

urn:lsid:zoobank.org:act:1FDCA9D7-546A-48FA-94E1-0053EB7F7C23

Fig. 23 ; Table 8

Diagnosis

Species of Dzhulfites with conch reaching 160 mm dm. Subadult stage with weakly trapezoidal, moderately depressed whorl profile (ww/wh =1.50–1.80) and broadly rounded venter; 10–13 coarse conical nodes on midflank per volution. Adult stage with numerous weak ribs and small ventrolateral nodes. Prongs of external lobe bifid or trifid; altogether 15–20 notches of E, A and L lobes.

Etymology

From the Latin ‘ brevis ’, meaning ‘low’ and ‘ sella ’, meaning ‘saddle’, after the low amplitude of lobes and saddles in the suture line.

Material examined

Holotype IRAN • Esfahan Province, Baghuk Mountain H section ; Hambast Formation, 5.70 m below top; illustrated in Fig. 23B ; MB.C.29748 .

Paratypes IRAN • 1 specimen; Esfahan Province, Baghuk Mountain ; Hambast Formation; MB.C.29746 • 1 specimen; Esfahan Province, Baghuk Mountain E section ; Hambast Formation; MB.C.29747 .

Description

The large paratype MB.C.29746 has 125 mm conch diameter, of which half of the last whorl belongs to the strongly weathered body chamber ( Fig. 23A ). The phragmocone is 90 mm in diameter and is partly crushed; it shows that the whorl profile is trapezoidal with a broadly rounded venter. The sculpture changes dramatically throughout ontogeny. At 40 mm dm there are 13 coarse, spiny ventrolateral nodes per volution; these nodes become weaker and more numerous so that the last 120° of the phragmocone have about 20 weak ventrolateral nodes, which are connected with weak and slightly sinuous radial ribs on the flank. The suture line of the specimen suffered from weathering, but, most probably, the prongs of the very short external lobe are bifid.

Holotype MB.C.29748 is a fairly well-preserved, fully septate specimen with 51 mm conch diameter ( Fig. 23B ). It has a weakly trapezoidal whorl profile with broadly rounded flanks and venter. The sculpture shows about ten coarse conical nodes, which are positioned on the midflank, on the last preserved volution.

The suture line of the holotype shows an external lobe with subparallel, weakly diverging flanks and weakly asymmetric, trifid prongs. All three saddles of the outer suture line are similar in shape, being inverted U-shaped and broadly rounded. The adventive lobe and the lateral lobe are similar in shape with parallel flanks and many small notches at the base. They differ in their depth; the adventive lobe is much deeper than the external lobe ( Fig. 23C ).

Remarks

Among the species of Dzhulfites , only D. nodosus is similar in conch shape and sculpture, but this species shows an applanate venter in the adult stage. Dzhulfites brevisellatus sp. nov. differs from D. spinosus and the other species of the genus in the suture line, which in D. brevisellatus sp. nov. shows much wider elements; particularly the saddles are wider than the lobes. In the shape of the suture line, D. brevisellatus sp. nov. has some resemblance to representatives of the family Xenodiscidae .

Stratigraphic range

Upper part of the Hambast Formation; 5.70 to 4.70 m below the extinction horizon ( Dzhulfites spinosus Zone to Shevyrevites shevyrevi Zone ).

Figures

Fig. 23. Dzhulfites brevisellatus Korn & Hairapetian sp. nov. A–B. Lateral and dorsal views. A. Paratype MB.C.29746, float. B. Holotype MB.C.29748, section H, -5.70 m.C. Suture line, holotype MB.C.29748, at 21.0 mm ww, 13.5 mm wh. D. Whorl profile proportions. Abbreviations: see Material and methods. Scale bar units= 1 mm.