The Changhsingian (Late Permian) ammonoids from Baghuk Mountain (Central Iran) Author Korn, Dieter 286CA4F3-7EBC-4AEF-A66A-B2508D001367 Museum für Naturkunde, Leibniz Institut for Research on Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany. dieter.korn@mfn.berlin Author Hairapetian, Vachik 1AB10F8F-4576-481B-9270-5DCD25110DBB Department of Geology, Esfahan (Khorasgan) Branch, Islamic Azad University, Esfahan, Iran. vhairap@gmail.com Author Ghaderi, Abbas 925F2B42-7326-4461-B2A6-83CB83ECCC63 Department of Geology, Faculty of Science, Ferdowsi University of Mashhad, Azadi Square, 9177948974, Mashhad, Iran. aghaderi@um.ac.ir Author Leda, Lucyna 81481AFA-C8EE-4E90-A954-FD0E7987621E Museum für Naturkunde, Leibniz Institut for Research on Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany. lucyna.skorpion3@wp.pl Author Schobben, Martin 44C2A45A-B16C-434F-8F22-FC9C0FCA2551 Utrecht University, Department of Earth Sciences, Princetonlaan 8 A, 3584 CB Utrecht, The Netherlands. & Department of Geology, Esfahan (Khorasgan) Branch, Islamic Azad University, Esfahan, Iran. schobbenmartin@gmail.com Author Akbari, Amir 3C9DB6F9-2034-418F-876C-49359D07D29F Department of Geology, Esfahan (Khorasgan) Branch, Islamic Azad University, Esfahan, Iran amakbari80@yahoo.com text European Journal of Taxonomy 2021 2021-10-27 776 1 106 journal article 3782 10.5852/ejt.2021.776.1559 453c885c-f427-4a38-ab97-dc14b686e126 2118-9773 5604715 226B6C59-8620-4A29-9BEF-359BE67A1A2C Paratirolites robustus Korn & Hairapetian sp. nov. urn:lsid:zoobank.org:act: 10C9CACF-9ED4-4E61-8140-FDBB70154F87 Figs 26–27 ; Table 11 Diagnosis Species of Paratirolites with conch reaching 120 mm dm. Subadult stage with trapezoidal, weakly depressed whorl profile (ww/wh =1.30–1.50) and rounded venter; 8–12 coarse, radially elongated midflank nodes per volution. Adult stage with trapezoidal and weakly depressed whorl profile Fig. 25 (next page). Paratirolites lanceolobatus Korn & Hairapetian sp. nov. A–E . Lateral and dorsal views. A . Holotype MB.C.29769, section B, float. B . Paratype MB.C.29751, section 1, float. C . Paratype MB.C.29770, section E, - 3.30 m . D . Paratype MB.C.29752, section A, float. E–H . Suture lines. E . Holotype MB.C.29769, at 13.5 mm wh. F . Paratype MB.C.29751, at 11.2 mm wh. G . Paratype MB.C.29757, at 11.2 mm wh. H . Paratype MB.C.29770, at 11.1 mm wh. I . Whorl profile proportions. Abbreviations: see Material and methods. Scale bar units= 1 mm . (ww/wh =1.00–1.10), flattened, tectiform venter and angular ventrolateral shoulder; numerous weak ribs on flank. Prongs of external lobe simple to trifid; altogether 12–17 notches of E, A and L lobes. Etymology From the Latin ‘ robustus ’, meaning ‘robust’, because of the coarse ribs. Material examined Holotype IRAN • Esfahan Province , Baghuk Mountain E section ; Hambast Formation , 2.95 m below top; illustrated in Fig. 26A ; MB.C.29778 . Fig. 26. Paratirolites robustus Korn & Hairapetian sp. nov. , lateral and dorsal views. A . Holotype MB.C.29778, section E, -2.95 m. B . Paratype MB.C.29782, float. Scale bar units =1 mm. Paratypes IRAN • 2 specimens ; Esfahan Province , Baghuk Mountain E section ; Hambast Formation ; MB.C.29776 to MB.C.29777 • 1 specimen ; Esfahan Province , Baghuk Mountain E section ; Hambast Formation ; MB.C.29779 • 1 specimen ; Esfahan Province , Baghuk Mountain G section ; Hambast Formation ; MB.C.29780 • 4 specimens ; Esfahan Province , Baghuk Mountain ; Hambast Formation ; MB.C.29781 to MB.C.29784 . Description Holotype MB.C.29778 has 80 mm conch diameter and consists of a rather well-preserved phragmocone and a more or less strongly weathered body chamber ( Fig. 26A ). Septal crowding indicates that the maximum phragmocone diameter is 48 mm . The conch shape changes during growth; there is a strongly trapezoidal whorl profile of the phragmocone and a weakly trapezoidal profile of the body chamber. The sculpture of the phragmocone shows 12 conical nodes, which are circular and symmetric in section in the penultimate whorl but become asymmetric and radially elongated towards the end of the phragmocone. The suture line of holotype MB.C.29778 has a Y-shaped external lobe, in which the prongs are weakly serrated including two notches. The adventive lobe is asymmetric and ventrally inclined with nearly parallel flanks and asymmetric notching. It is dorsolaterally followed by an asymmetric lateral saddle and a nearly symmetric lateral lobe with seven small notches ( Fig. 27A ). The slightly smaller paratype MB.C.29782 ( 73 mm dm) is very similar in conch shape and suture line. The penultimate whorl has eight coarse conical nodes, which transform, at the end of the phragmocone, into weakly curved elongated nodes ( Fig. 26B ). The suture line has an external lobe with weakly diverging Fig. 27. Paratirolites robustus Korn & Hairapetian sp. nov. A . Suture line, holotype MB.C.29778, at 14.2 mm wh. B . Suture line, paratype MB.C.29782, at 13.2 mm wh. C . Whorl profile proportions. Abbreviations: see Material and methods. Scale bar units=1 mm. Table 11. Conch dimensions (partly estimated) and ratios of selected specimens of Paratirolites robustus Korn & Hairapetian sp. nov. from Baghuk Mountain.

Specimen	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZR
MB.C.29778	80.0	29.0	26.7	35.9	25.2	0.36	1.09	0.45	2.13	0.06
MB.C.29782	73.4	27.4	26.0	30.9	24.2	0.37	1.05	0.42	2.23	0.07
MB.C.29780	61.5	26.5	20.6	26.4	–	0.43	1.29	0.43	–	–

flanks, an asymmetric ventrolateral saddle and a weakly asymmetric, strongly notched adventive lobe with nearly flat base and parallel flanks ( Fig. 27B ). Remarks Paratirolites robustus sp. nov. differs from the most similar of the Central Iranian species P. lanceolobatus sp. nov. in the stouter whorl profile (ww/wh = 1.20 in P. robustus sp. nov. at 70 mm conch diameter and only 0.85 in P. lanceolobatus ). Furthermore, P. lanceolobatus sp. nov. has non-serrated prongs of the parallel-sided external lobe. Paratirolites robustus sp. nov. differs from P. vediensis in the rounded venter and from P. kittli in the radially elongated nodes of the subadult stage and the presence of weak radial ribs of the body chamber. Stratigraphic range Upper part of the Hambast Formation; 3.20 to 2.90 m below the extinction horizon (uppermost part of the Paratirolites lanceolobatus Zone to Paratirolites kittli Zone ).