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 Abichites infirmis Korn & Hairapetian sp. nov. urn:lsid:zoobank.org:act: DF627B6D-3446-4B02-89B2-81ED420C876D Fig. 60 ; Table 34 Diagnosis Species of Abichites with conch reaching 50 mm dm. Subadult stage with oval, weakly compressed whorl profile (ww/wh =0.60–0.80) and rounded venter; very weak, rounded nodes. Adult stage with weakly subtrapezoidal, weakly compressed whorl profile (ww/wh =0.60–0.80) with weakly converging flat flanks, weakly flattened venter and narrowly subangular ventrolateral shoulder. Sculpture with faint plications. Prongs of external lobe simple; altogether 5–6 notches of E, A and L lobes. Etymology From the Latin ‘ infirmis ’, meaning ‘barely visible’, because of the weak sculpture. Material examined Holotype IRAN • Esfahan Province , Baghuk Mountain G section ; Hambast Formation, 0.40 m below the top; illustrated in Fig. 60A ; MB.C.30086 . Paratypes IRAN • 1 specimen ; Esfahan Province , Baghuk Mountain 1 section ; Hambast Formation ; MB.C.30083 • 1 specimen ; Esfahan Province , Baghuk Mountain C section ; Hambast Formation ; MB.C.30084 • 1 specimen ; Esfahan Province , Baghuk Mountain E section ; Hambast Formation ; MB.C.30085 • 2 specimens ; Esfahan Province , Baghuk Mountain G section ; Hambast Formation ; MB.C.30087 to MB.C.30088 . Description Holotype MB.C.30086 is a rather well-preserved specimen with 42 mm conch diameter ( Fig. 60A ). The whorl profile of the body chamber is subtrapezoidal with a narrowly rounded umbilical margin, flat and weakly converging flanks, a subangular ventrolateral shoulder and a flattened but still broadly rounded venter. Its ww/wh ratio is 0.70 and the whorl embraces the preceding one only weakly. The shell appears to be smooth except for very faint plications. The suture line of the holotype has a parallel-sided external lobe that has a width/depth ratio of ~ 0.75. It is deeper than the adventive lobe and possesses unsubdivided lanceolate prongs. The ventrolateral saddle is inverted U-shaped and symmetric and the weakly asymmetric, parallel-sided adventive lobe is subdivided into two secondary notches. The narrow lateral saddle is also inverted U-shaped and followed by a parallel-sided lateral lobe with two notches ( Fig. 60B ). Fig. 60. Abichites infirmis Korn & Hairapetian sp. nov. A . Lateral and dorsal view, holotype MB.C.30086, section G, -0.40 m. B . Suture line, holotype MB.C.30086, at 21.5 mm dm, 9.1 mm wh. Abbreviations: see Material and methods. Scale bar units=1 mm. Table 34. Conch dimensions (partly estimated) and ratios of selected specimens of Abichites infirmis Korn & Hairapetian sp. nov. from Baghuk Mountain.

Specimen	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZR
MB.C.30086	41.6	10.4	14.7	15.5	13.6	0.25	0.71	0.37	2.21	0.07
MB.C.30088	36.9	8.8	13.2	13.6	12.3	0.24	0.67	0.37	2.25	0.07
MB.C.30087	33.6	7.7	12.4	12.6	11.4	0.23	0.62	0.38	2.29	0.08
MB.C.30083	33.1	9.4	12.4	13.3	11.3	0.28	0.76	0.40	2.31	0.09

Remarks Abichites infirmis differs from most of the species of the genus in the lack of coarse ribs or nodes. Similar species are A. paucinodus (which possesses few coarse nodes on the flanks) and A. terminalis (with an oval whorl profile). Stratigraphic range Upper part of the Hambast Formation; 0.40 to 0.05 m below the extinction horizon ( Arasella minuta Zone ).