Lutites profundus 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 : 81-83

Lutites profundus Korn & Hairapetian gen. et sp. nov.

urn:lsid:zoobank.org:act:BB88C301-E69F-4E4B-8B25-F086D3BC6EEC

Fig. 53 ; Table 27

Diagnosis

Species of Lutites gen. nov. with conch reaching 125 mm dm. Subadult stage with subcircular, compressed whorl profile (ww/wh =0.70–0.80) and rounded venter; about 13 coarse ventrolateral nodes per volution. Adult stage with subtrapezoidal, compressed whorl profile (ww/wh =0.70–0.75), flat or concave venter and angular ventrolateral shoulder; weak dorsolateral ribs and elongated ventrolateral nodes. Prongs of external lobe trifid; altogether about 19 notches of E,A and L lobes.

Etymology

From the Latin ‘ profundus ’, meaning ‘deep’, because of the deep external lobe.

Material examined

Holotype IRAN • Esfahan Province, Baghuk Mountain E section ; Hambast Formation; illustrated in Fig. 53 ; MB.C.30003 .

Paratypes IRAN • 1 specimen; Esfahan Province, Baghuk Mountain C section ; Hambast Formation; MB.C.30002 • 1 specimen; Esfahan Province, Baghuk Mountain E section ; Hambast Formation; MB.C.30004 • 1 specimen; Esfahan Province, Baghuk Mountain G section ; Hambast Formation; MB.C.30005 • 3 specimens; Esfahan Province, Baghuk Mountain H section ; Hambast Formation; MB.C.30006 to MB.C.30008 .

Description

Holotype MB.C.30003 is a rather well-preserved specimen with 86 mm conch diameter, in which two whorls can be studied ( Fig. 53A ). One third of the last volution belongs to the body chamber and the last four septa of the phragmocone are crowded. In the adult stage, the compressed whorl profile (ww/ wh= 0.75) shows a broadly rounded umbilical margin with an oblique umbilical wall. The whorl profile is widest on the inner flank, from where the concave flanks converge towards the angular ventrolateral shoulder. The venter is concave in this growth stage. Half a volution back the venter is flat and another half whorl back, a rounded venter can be seen belonging to a subcircular, compressed whorl section (ww/wh =0.80). The sculpture experiences a change in strength during the last volution. The penultimate volution has ten coarse ventrolateral nodes, which are connected with weak and rounded radial ribs. These nodes become weaker and more numerous at the end of the phragmocone, but they are still present on the body chamber (12 on a distance of 120 degrees). Here, they are elongate and alternate, in their positions, with low umbilical ribs.

The suture line of the holotype has a narrow and deep external lobe (deeper than the adventive lobe) with parallel flanks in the lower part. Its prongs are parallel-sided with asymmetric base and possesses three small notches. The ventrolateral saddle is narrow and asymmetric; it borders the adventive lobe that is widest near its base. It shows two groups of five very narrow notches. The nearly symmetric and inverted U-shaped lateral saddle is higher than the ventrolateral saddle. The asymmetric lateral lobe with less steep dorsal flank has also two groups of narrow notches, a ventral group with two and a dorsal group with three notches ( Fig. 53B ).

Remarks

Lutites profundus gen. et sp. nov. is similar to L. lyriformis gen. et sp. nov. but differs in the much coarser sculpture of the terminal body chamber, which shows only very weak ribs in the latter species but ventrolateral nodes in L. profundus gen. et sp. nov. All the other species of Lutites gen. nov. with a slender conch also show a much weaker sculpture.

Stratigraphic range

Upper part of the Hambast Formation; 1.60 to 1.20 m below the extinction horizon ( Lutites profundus Zone ).

Figures

Fig. 53. Lutites profundus Korn & Hairapetian gen. et sp. nov. A. Lateral and dorsal view, holotype MB.C.30003, section E, float. B. Suture line, holotype MB.C.30003, at 60.0 mm dm, 19.6 mm wh. C. Whorl profile proportions. Abbreviations: see Material and methods. Scale bar units =1 mm.