Foordiceras ascetum, Korn & Hairapetian, 2025

Foordiceras ascetum sp. nov.

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Fig. 18 View Fig ; Table 12 View Table 12

Diagnosis

Species of Foordiceras with thinly discoidal, subevolute conch (ww/dm ~ 0.33; uw/dm ~0.43), nearly equidimensional whorl profile (ww/wh ~1.00) and high coiling rate (WER ~ 2.20) at a conch diameter of 60 mm. Whorl profile trapezoidal with weakly divergent, flattened flanks; venter flattened, umbilical margin incipient. Sculpture with about 10 coarse, blunt ventrolateral ribs per volution. Suture line with a very shallow external lobe and a very shallow, broadly rounded lateral lobe.

Etymology

From the Greek ‘ἀσκητός’= ‘decorated’; because of the sculpture.

Type material

Holotype

IRAN – Esfahan Province • Baghuk Mountain ; Hambast Formation, Vedioceras beds ( late Wuchiapingian); 2011; Korn et al. leg.; illustrated in Fig. 18 View Fig ; MB.C.32124 .

Description

Holotype MB.C.32124 is an internal mould with a diameter of 86 mm, but the last portion is poorly preserved ( Fig. 18B View Fig ). The conch is, at 62 mm diameter, thinly discoidal and subevolute (ww/dm=0.33; uw/dm = 0.43) with a high coiling rate (WER = 2.21). The whorl profile is weakly compressed (ww/ wh = 0.98) and rounded trapezoidal with a nearly flat venter and a broadly rounded ventrolateral shoulder. The weakly divergent flanks are flattened; an umbilical margin is only barely visible ( Fig. 18A View Fig ). The sculpture has five prominent conical nodes per half volution in the outer area of the flank; these nodes show a low extension on the flank towards the umbilicus. The nodes are narrower than their interspaces. The suture line shows shallow, broadly rounded lobes on venter and flanks ( Fig. 18C View Fig ). The last half volution of the phragmocone has about 16 chambers (CLI=11).

Remarks

Foordiceras ascetum sp. nov. differs from F. eicosacanthum sp. nov. and F. decacanthum sp. nov. in the nearly equidimensional whorl profile (ww/wh =1.00), which is depressed in the other two species (ww/ wh= 1.75 in F. eicosacanthum and = 1.25 in F. decacanthum ). Another criterion to separate F. ascetum from the rather similar F. decacanthum is in the width of the nodes; in F. ascetum they are only half as wide as their interspaces, while they are wider than the interspaces in F. decacanthum .