Distichophyllia cf. norica ( Frech, 1890 )

Vasseur, Raphaël & Lathuilière, Bernard, 2021, Pliensbachian corals from the Western Tethys, Geodiversitas 43 (22), pp. 1187-1291 : 1248

Distichophyllia cf. norica ( Frech, 1890)

( Fig. 41 )

Montlivaltia norica Frech, 1890: 39-40 , pl. 3, fig. 9, pl. 10, figs 1-5, pl. 13, figs 1-7, pl. 18, fig. 17.

Montlivaltia cupuliformis – Reuss 1854: 74, 102, pl. 6, fig. 16-17.

Distichophyllia norica – Roniewicz 1989: 39, pl.6, fig.2-4 (cum syn.).

Distichophyllia sp. 2 – Vasseur 2018: 178-179, fig. 3.30.

TYPE MATERIAL. — Syntypes BSP AS X II 46, 48, Reuss 1854: 74, 102, pl. 6, fig. 16-17. TYPE HORIZON. — Zlambach beds, Triassic . TYPE LOCALITY. — Grosser Zlambach graben. Studied samples. — Two specimens: CPUN 2310 A2, AM16174-1. GEOGRAPHIC AND STRATIGRAPHIC RANGES. — Pliensbachian of Amellagou ( High Atlas of Morocco).

DESCRIPTION

Solitary, probably conical corallum, elliptical in outline.Radial elements are costosepta slightly bicuneiform for the first orders, thin for the last ones, often in zigzag and organized in 3 or 4 size orders following a relatively strict hexameral symmetry. Septa are compact, free, ornamented with granules sometimes attenuated by stereomal layer deposits on lateral faces and have a more or less wavy zigzag midseptal line. No columella but an axial fossa elongated that defines a bilateral symmetry. Endotheca made of many peripheral vesicular dissepiments. Wall parathecal. An epicostal epitheca s.l. seems to cover the external parts of the corallum.

Calicular diameter: 19.9 × 25.9 – 20.5 × 24 – 17.4 × 23.8 mm – Number of septa: approximately 60 to 70 – Septal density: 2 to 3 per 2 mm – Ratio great calicular diameter (D) / length of fossa (f) (in distal part of the corallum) = approximately 2.5.

SIMILARITIES AND DIFFERENCES

This species differs from Distichophyllia pauciseptata n. sp. by a higher number of septa, a more pronounced bilateral symmetry and less bicuneiform first-order septa. The present species is distinguished from the typical D. norica by the high elongation of the fossa in distal part and also of the calice in the bilateral plan and also a strong hierarchy in thickness among the size orders of septa. The size of granules is also very low in the present form. The ratio D / f seems significant in the present state of our sampling but D. norica seems so variable that we renounced to the creation of a new species. The synonymy with M. cupuliformis is not certain that is why we prefer to keep the name of norica to describe this species despite the anteriority of M. cupuliformis .

Figures

FIG. 41. — Distichophyllia cf. norica (Frech, 1890): A, lateral view of the specimen CPUN 2303A1-3; B, distal view of the specimen CPUN AM16188-15, C, detail in transverse thin section of the specimen CPUN 2303A1-3; D, transverse thin section of the specimen CPUN 2303A1-3; E, specimen pictured in the field (Amellagou, Maroc). Scale bars: A, B, E, 1 cm; C, 1 mm; D, 4 mm.