Liroceras leptum Korn & Hairapetian, 2025, sp. nov.

Liroceras leptum sp. nov. urn:lsid:zoobank.org:act: 43D3AA7B-CCE4-43FD-B6A6-D9B7A27DB882 Fig. 25; Table 19 Diagnosis Species of Liroceras with thinly pachyconic, subinvolute conch (ww/dm ~ 0.68; uw/dm ~ 0.17), moderately depressed whorl profile (ww/wh ~1.45) and very high coiling rate (WER ~2.30) at a conch diameter of 40 mm. Whorl profile with broadly arched venter and flanks, broadly rounded umbilical margin, convex umbilical wall and moderately deep imprint zone (IZR ~0.28). Without sculpture. Suture line with very shallow and wide external, lateral and umbilical lobes. Etymology From Greek ‘λεπτός’= ‘small, weak’; because of the rather small-sizes material. Type material Holotype IRAN – Esfahan Province • Baghuk Mountain; Hambast Formation, Vedioceras beds (late Wuchiapingian); 2011; Korn et al. leg.; illustrated in Fig. 25; MB.C.32138. Paratypes IRAN – Esfahan Province • 2 specimens; same data as for holotype; 2010; Korn et al. leg.; MB.C.32139, MB.C.32140. Description The best-preserved specimen is the obliquely deformed small holotype MB.C.32138 with a conch diameter of 41 mm (Fig. 25B). The conch geometry can only be reconstructed. According to this, the conch is thinly pachyconic and subinvolute (ww/dm=0.68; uw/dm=0.17) with a very high coiling rate (WER =2.31) and a moderately wide whorl overlap (IZR = 0.28). The whorl profile is weakly depressed (ww/wh =1.44) with a broadly convex venter that merges continuously with the flanks the flanks. The umbilical margin is broadly rounded and the umbilical wall is convex (Fig. 25A). The suture line is nearly straight and shows very broad and shallow lobes on the area consisting of venter and flanks and the umbilical wall (Fig. 25C). Remarks The material of the new species does not show whether the umbilical extensions characteristic of the genus was present in the adult stage; therefore, assignment to Liroceras is not entirely certain. L. leptum sp. nov. differs from the other Late Permian species of the genus in the opened umbilicus and the slenderer conch; ww/dm ratio for a conch diameter of 40–50 mm is below a value of 0.70, but in the other species it is above 0.80.