Paratirolites baghukensis Korn & Hairapetian & Ghaderi & Leda & Schobben & Akbari 2021, sp. nov.
Creators: name: Korn, Dieter
name: Hairapetian, Vachik
name: Ghaderi, Abbas
name: Leda, Lucyna
name: Schobben, Martin
name: Akbari, Amir
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Cephalopoda
Ammonoidea
Dzhulfitidae
Paratirolites
Paratirolites baghukensis

description: Paratirolites baghukensis Korn & Hairapetian sp. nov.
urn:lsid:zoobank.org:act: 27027DEB-9F15-4F61-8EA3-3F15E997A1D9
Figs 33–34; Table 16
Diagnosis
Species of Paratirolites with conch reaching 130 mm dm. Subadult stage with trapezoidal, weakly depressed whorl profile (ww/wh =1.00–1.20) and rounded venter; about 12 moderately coarse ribs ending in conical ventrolateral nodes per volution. Adult stage with trapezoidal and weakly compressed whorl profile (ww/wh =0.70–0.90), flattened tectiform venter and subangular ventrolateral shoulder; numerous sharp ribs ending in sharp radially elongated ventrolateral nodes. Prongs of external lobe usually trifid; altogether 13–15 notches of E, A and L lobes.
Etymology
Named after the occurrence at Baghuk Mountain.
Material examined
Holotype IRAN • Esfahan Province, Baghuk Mountain G section; Hambast Formation; illustrated in Fig. 33A; MB.C.29868.
Paratypes IRAN • 2 specimens; Esfahan Province, Baghuk Mountain 1 section; Hambast Formation; MB.C.29849 to MB.C.29850 • 4 specimens; Esfahan Province, Baghuk Mountain A section; Hambast Formation; MB.C.29851 to MB.C.29854 • 5 specimens; Esfahan Province, Baghuk Mountain C section; Hambast Formation; MB.C.29855 to MB.C.29859 • 8 specimens; Esfahan Province, Baghuk Mountain E section; Hambast Formation; MB.C.29860 to MB.C.29867 • 7 specimens; Esfahan Province, Baghuk Mountain G section; Hambast Formation; MB.C.29869 to MB.C.29875 • 1 specimen; Esfahan Province, Baghuk Mountain H section; Hambast Formation; MB.C.29876 • 3 specimens; Esfahan Province, Baghuk Mountain; Hambast Formation; MB.C.29877 to MB.C.29879.
Description
Holotype MB.C.29868 has 70 mm conch diameter and is fairly well-preserved but slightly corroded. The last third of the terminal volution belongs to the body chamber (which is thus only incompletely preserved); adulthood of the specimen is obvious because of the crowding of the last septa of the phragmocone (Fig. 33A). The penultimate of the preserved whorls shows a trapezoidal profile with a rounded venter. The body chamber finally shows a trapezoidal whorl profile with weakly diverging flanks, an angular ventrolateral shoulder and a nearly flat, tectiform venter. The sculpture changes with the beginning of the terminal body chamber, but this change is continuous without sudden breaks. One subadult volution has ten isolated spiny ventrolateral nodes.Already towards the end of the phragmocone, these nodes become radially elongate and form coarse ribs across the flank. At the beginning of the terminal body chamber, the ventrolateral nodes weaken and finally, only sharp ribs, about 15 per quarter of a volution, are present.
The suture line of holotype MB.C.29868 shows a slightly pouched external lobe with trifid, asymmetric prongs. The ventrolateral saddle is weakly inflated, the adventive and lateral lobes are flattened at the base and subdivided in five and four notches, respectively (Fig. 33C).
Paratype MB.C.29860 (Fig. 33B) is smaller with 61 mm conch diameter but confirms the description given for the holotype. It shows four whorls preserved and thus allows for the study of the sculpture of the inner volutions.
The two larger paratypes MB.C.29874 and MB.C.29850 (Fig. 34) show then the transformation into the weakly ornamented adult stage, in which a tendency towards a parallel-sided whorl profile is visible.
Remarks
Paratirolites baghukensis sp. nov. belongs to the slender species of the genus. It differs from the other species of the genus in the sharp ribs on the adult body chamber. Paratirolites multiconus also has a slender conch, but differs from P. baghukensis sp. nov. in the much more numerous ventrolateral nodes.
Stratigraphic range
Upper part of the Hambast Formation; 3.10 to 2.35 m below the extinction horizon (Paratirolites kittli Zone).
description: Published as part of Korn, Dieter, Hairapetian, Vachik, Ghaderi, Abbas, Leda, Lucyna, Schobben, Martin & Akbari, Amir, 2021, The Changhsingian (Late Permian) ammonoids from Baghuk Mountain (Central Iran), pp. 1-106 in European Journal of Taxonomy 776 on pages 49-52, DOI: 10.5852/ejt.2021.776.1559, http://zenodo.org/record/5604715