Epitornoceras transmediterraneum, Korn & Bockwinkel, 2022

Korn, Dieter & Bockwinkel, Jürgen, 2022, The tornoceratid ammonoids from the Roteisenstein Formation of Dillenburg (Cephalopoda, Ammonoidea), European Journal of Taxonomy 806, pp. 32-51 : 43-44

Epitornoceras transmediterraneum sp. nov.

urn:lsid:zoobank.org:act:CFD7324D-6824-4856-AD22-4792DB3CE1EF

Epitornoceras mithracoides – Bockwinkel et al. 2009: 65, text-figs 1–2; 2013a: 57, text-figs 4d, 58–59; 2015: 148, text-figs 31–32; 2017: 346, text-figs 34–35.

Diagnosis

Epitornoceras reaching about 100 mm conch diameter. Thinly discoidal and involute adult stage (ww/dm ~ 0.35; umbilicus closed at 50 mm dm); whorl profile compressed (ww/wh ~ 0.65 at 50 mm dm); whorl expansion rate high (WER ~ 2.20). Flanks weakly convex, convergent, umbilical margin pronounced, umbilical wall on the inside flattened caused by an internal shell thickening throughout ontogeny. Without any ventrolateral grooves. Suture line with broadly rounded, nearly symmetric adventive lobe with parallel flanks; width of the adventive lobe less than the lobe depth.

Etymology

After the occurrence beyond the Mediterranean Sea.

Type material

Holotype MOROCCO • Anti-Atlas , Dar Kaoua; late Givetian; figured by Bockwinkel et al. (2009: text-fig. 2); MB.C.19101.1 .

Paratypes MOROCCO • 2 specs; Anti-Atlas , Tafilalt , Dar Kaoua; late Givetian; MB.C.19101.2–3 • 10 specs; Anti-Atlas , Tafilalt , Hassi Nebech; late Givetian; MB.C.22101.1–9 , MB.C.22137 • 1 spec.; Anti-Atlas , Tafilalt , Ouidane Chebbi; late Givetian; MB.C.26510 • 6 specs; Anti-Atlas , Ma’der , “ Butte 760” W of Ait Ou Amar, 8 km WSW of Bou Dib; late Givetian; MB.C.25114.1–6 .

Description

For a detailed description of the species ( Bockwinkel et al. 2009, 2013a, 2015, 2017).

Remarks

Epitornoceras transmediterraneum from the Anti-Atlas of Morocco differs in two aspects from E. mithracoides from the Rhenish Mountains: (1) the suture line; measured at half the depth of the adventive lobe characterised by nearly parallel flanks, the width of this lobe is 100% of the lobe depth in E. mithracoides , but only about 75% in E. transmediterraneum ; (2) the shape of the umbilical wall is funnel-shaped in the juvenile stage but evenly rounded in the adult stage in E. mithracoides , but obliquely flattened caused by an umbilical shell thickening in E. transmediterraneum , leading to a funnel-shaped umbilicus with a distinct umbilical edge of the internal mould throughout ontogeny.