Distichophyllia norica ( Frech, 1890 )

Vasseur, Raphaël & Lathuilière, Bernard, 2021, Pliensbachian corals from the Western Tethys, Geodiversitas 43 (22), pp. 1187-1291 : 1244-1248

Distichophyllia norica ( Frech, 1890)

( Fig. 40 )

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 2303 A1-3, CPUN AM16188-15. GEOGRAPHIC AND STRATIGRAPHIC RANGES. — Pliensbachian of Amellagou ( High Atlas of Morocco).

DESCRIPTION

Solitary, conical corallum, elliptical in outline. Radial elements are slightly bicuneiform costosepta for the first order, 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 strong granules sometimes angular on lateral faces and seem to have a more or less wavy zigzag midseptal line that the poor preservation does not allow to confirm. No columella but an axial fossa elongated that defines a bilateral symmetry. Endotheca made of peripheral vesicular dissepiments.Wall parathecal.An epicostal epitheca s.l. seems to cover the external parts of the corallum. Calicular diameter: 26 to 28 mm – Distance between calice centers: 55 to 70 mm – Septal density: 2 to 3 per 2 mm.

SIMILARITIES AND DIFFERENCES

The present species has no equivalent among Triassic Distichophyllia in terms of number of septa and hierarchy of septal thickness. It differs from the other Distichophyllia described herein by the big size and the particular shape of the lateral granules of septa. In addition, this species differs from Distichophyllia pauciseptata n. sp. by a higher number of septa, a pronounced bilateral symmetry, a less defined hexameral symmetry and also less bicuneiform septa. The endotheca seems less abundant and costal parts are smaller. These characters make this species close to Distichophyllia cf. norica described thereafter. The synonymy with M. cupuliformis is not certain that is why we prefer to keep the name norica to describe this species despite the anteriority of M. cupuliformis .

Figures

FIG. 40. — Distichophyllia norica (Frech, 1890): A, distal view of the specimen CPUN AM16174-1; B, transverse thin section of the specimen CPUN 2310A2; C, detail in transverse thin section of the septal structure of the specimen CPUN 2310A2; D, detail in transverse thin section of the mid-septal lines (bright) of the specimen CPUN AM16174-1. Scale bar: A, 5 mm; B, 4 mm; C, 1 mm; D, 2 mm.