Lutites paucis 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 : 77-78

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

urn:lsid:zoobank.org:act:9C85D567-DA54-463F-8CE3-BFDBABD83928

Fig. 50 ; Table 25

Diagnosis

Species of Lutites gen. nov. with conch reaching 70 mm dm. Subadult stage with circular, slightly compressed whorl profile (ww/wh =0.90–1.00) and broadly rounded venter; very coarse conical ventrolateral nodes. Adult stage with subtrapezoidal, slightly compressed whorl profile (ww/wh =0.80), flattened venter and subangular ventrolateral shoulder; without ribs or nodes. Prongs of external lobe simple; altogether 11 notches of E, A and L lobes.

Etymology

From the Latin ‘ paucis ’, meaning ‘fewer’, because of the low number of lobes and nodes.

Material examined

Holotype IRAN • Esfahan Province, Baghuk Mountain C section ; Hambast Formation, 2.45 m below the top; illustrated in Fig. 50A ; MB.C.29991 .

Paratypes IRAN • 2 specimens; Esfahan Province, Baghuk Mountain C section ; Hambast Formation; MB.C.29992 to MB.C.29993 .

Description

Holotype MB.C.29991 is a partly corroded specimen with 64 mm conch diameter with two thirds of the last volution belonging to the body chamber ( Fig. 50A ). At the end of the body chamber, the whorl profile is subtrapezoidal with a broadly rounded umbilical margin, converging flanks, a narrowly rounded ventrolateral shoulder and a flattened venter. By contrast, the whorl profile is trapezoidal at the beginning of the body chamber and subcircular in the last portion of the phragmocone. The sculpture of the phragmocone consists of very coarse conical ventrolateral nodes (eight per volution). The body chamber appears to be smooth.

The suture line of the holotype has a large external lobe with weakly diverging flanks and simple, narrow and lanceolate prongs. The ventrolateral saddle is narrowly rounded and the lateral saddle is weakly inflated. Both the adventive lobe and the lateral lobe are parallel-sided and both characterised by five notches that are very dissimilar in size ( Fig. 50B ).

Remarks

Lutites paucis gen. et sp. nov. differs from the other species of the genus in the stouter conch, the only weakly flattened venter and the lower number of conical nodes. The new species may represent an intermediate form between Alibashites and Lutites gen. nov.

Stratigraphic range

Upper part of the Hambast Formation; 2.45 m to 1.20 m below the extinction horizon (uppermost part of the Paratirolites kittli Zone to the Lutites profundus Zone ).

Figures

Fig. 50. Lutites paucis Korn & Hairapetian gen. et sp. nov. A. Lateral and dorsal view, holotype MB.C.29991, section C, -2.45 m. B. Suture line, holotype MB.C.29991, at 13.7 mm wh. Abbreviation: see Material and methods. Scale bar units =1 mm.