Protostylophyllum praenuntians

Protostylophyllum praenuntians (Volz 1896)

(Fig. 52)

Stylophyllum praenuntians Volz, 1896: 87, pl. XI, fig. 1-4 (non Cuif 1973: 254, fig. 22b, c).

Protostylophyllum praenuntians – Roniewicz & Michalík 2002: 156, fig. 5.3a-e, 5.4a-b. — Vasseur 2018: 315-316, fig. 3.84.

TYPE MATERIAL. — Holotype: MGUWr 71sz, Volz 1896: 87, pl. XI, fig. 1-4. TYPE HORIZON. — Carnian, Late Triassic. TYPE LOCALITY. — Valparola, Southern Alps. STUDIED SAMPLES. — Two specimens: CPUN AM16164bis4, CPUN 2303 A5-1. GEOGRAPHIC AND STRATIGRAPHIC RANGES. — Pliensbachian of Amellagou (High Atlas of Morocco), Trias (Carnian) of San Cassiano (Italia) and western Carpathian (Slovakia).

DESCRIPTION

Solitary, subcylindrical coral, subcircular in outline. Radial elements are free, straight, subcompact septa with a typically stylophyllid structure. Some septal elements dissociate at the inner edge to produce the columella. In fact, a strong spongypapillose columella appears in depth, filling the whole axial space. The inner edge of septa is widen in transverse section and these bulges hold sharp lateral granules. This unusual organization for corals has not been described on the holotype. The septal apparatus is very regular and reveals an almost perfect hexameral symmetry with 4 or 5 distinct size orders of septa. The width of septa vary periodically from the periphery to the inner edge, which probably indicates a quite slack frame made of septal spines. The septal apparatus progressively retreats peripherally in the distal part of the corallum that shows no columella. Endotheca made of thin tabular or vesicular dissepiments. No synapticulae. An epitheca s.l. wraps the corallite. Wall probably parathecal.

Calicular diameter: 12.5 to 26 mm – Number of septa: 83 to 103 – Septal density: 3 to 4 per 2 mm.