Paratirolites rubens 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 : 33-34

Paratirolites rubens Korn & Hairapetian sp. nov.

urn:lsid:zoobank.org:act:C8D262EC-926D-4CAB-AE08-BB8C158CE276

Fig. 24 ; Table 9

Diagnosis

Species of Paratirolites with conch reaching 110 mm dm. Subadult stage with broadly oval, moderately depressed whorl profile (ww/wh =1.60) and broadly rounded venter; about 8 coarse ventrolateral nodes per volution. Adult stage with broadly oval, weakly depressed whorl profile (ww/wh = 1.30), broadly rounded venter and rounded ventrolateral shoulder; coarse ventrolateral nodes. Prongs of external lobe unserrated; altogether 16 notches of E, A and L lobes.

Etymology

From the Latin ‘ rubens ’, meaning ‘red’, because of the red limestone horizon where the material comes from.

Material examined

Holotype IRAN • Esfahan Province, Baghuk Mountain E section ; Hambast Formation; illustrated in Fig. 24 ; MB.C.29749 .

Paratype IRAN • 1 specimen; Esfahan Province, Baghuk Mountain E section ; Hambast Formation; MB.C.29750 .

Description

Holotype MB.C.29749 is a rather well-preserved individual of 50 mm conch diameter ( Fig. 24A ). It is fully chambered with septal crowing at the end; therefore the adult diameter including body chamber has been about 90 mm. The whorl profile is, at 50 mm conch diameter, broadly oval (ww/wh =1.80) with broadly convex flanks and venter. Half a volution earlier, the ww/wh ratio is even higher (1.90). The sculpture consists of eight coarse conical nodes with a position on the midflank of the last volution; the penultimate volution bears only six nodes.

The suture line of the holotype has a narrow external lobe that is wider near its base and weakly constricted in the upper part. It possesses very narrow, non-serrated prongs. A narrow and slightly inflated ventrolateral saddle and an asymmetric adventive lobe with ten little notches follow on the sides of the venter, while the continuously rounded lateral saddle and the nearly symmetric lateral lobe (with five small notches) have a position on the flank ( Fig. 24B ).

Remarks

Paratirolites rubens sp. nov. is the species of the genus with the lowest number of ventrolateral nodes. Furthermore, the broadly rounded venter is a criterion of clear separation from species such as P. vediensis

and P. kittli . There is also some similarity to the species Dzhulfites spinosus and D. hebes , but these differ in the very short external lobe.

Stratigraphic range

None of the specimens was collected in situ, but according to the intensive red colour of the host sediment, a position in the Hambast Formation about five metres below the extinction horizon is most likely (probably Shevyrevites shevyrevi Zone ).

Figures

Fig. 24. Paratirolites rubens Korn & Hairapetian sp. nov. A. Lateral and dorsal view, holotype MB.C.29749, section E, float. B. Suture line, holotype MB.C.29749, at 36.0 mm dm, 22.0 mm ww, 13.0 mm wh. Abbreviations: see Material and methods. Scale bar units =1 mm.