Margarosmilia adhios, Roniewicz, 2011

Roniewicz, Ewa, 2011, Early Norian (Triassic) corals from the Northern Calcareous Alps, Austria, and the intra-Norian faunal turnover, Acta Palaeontologica Polonica 56 (2), pp. 401-428 : 416

Margarosmilia adhios sp. nov.

Fig. 5G, H .

Etymology: From Greek adhios , empty; in reference to the empty axial space.

Type series: Holotype GBA 2009 /019/19 and paratype 2009/019/18.

Type locality: Austria, Northern Calcareous Alps , southern Dachstein Plateau, site ca. 50 m north−west of Feisterscharte .

Type horizon: Norian, Lacian 1, Epigondolella quadrata Conodont Zone ; light grey Dachsteinkalk.

Diagnosis.— Margarosmilia of ca. 50 septa at a corallite diameter of 6 mm, well developed septa of first three size orders, rare S4 septa, and a large axial pit. Endotheca differentiated into axial extended, flat dissepiments and peripheral small, vesicular ones.

Comparison.—The species differs from the congeneric species in small corallite diameters and in zonation of the endotheca.

Material.— The type series and GBA 2009 /019/16, all with thin sections .

Measurements (in mm): Description.—Axial pit relatively large and empty. The S1 to S3 septa fusiform, wavy adaxially and very thick peripherally. The S2 septa are shorter than the S1septa, the S3 septa reach about half the length of the S1septa, the S4 septa rudimentary, developed in the form of thin blades. Endotheca peripherally built of high vesiculae, smaller at the circumference than at the zone of maximum thickening of the septa; the axial area built of flat dissepiments delineating a subhorizontal calicular floor. Wall epithecal, very thin, rarely preserved.

Microstructure.—In the peripheral, fusiform septal portion, the zigzag midline is preserved with clearly defined lateral trabeculae.

Stratigraphic and geographic range.—As for the type material.

Figures

Fig. 5. Margarosmiliid corals from vicinity of Feisterscharte, Austria, early Norian, Triassic. A–C. Ceriostella aff. variabilis Roniewicz and Stanley, 1998. A. GBA 2009/019/20; a colony in polished section. B. GBA 2009/019/22; transverse thin sections (B1, B2), note cerioid colony and a lack of columella; longitudinal section (B3) showing mode of growth of corallites at the periphery of lamellar colony. C. GBA 2009/019/23a; calice in longitudinal/oblique section showing rare granules on the septal side and internal border micromorphology (at the middle). D. Magarosmilia nova Turnšek, 1991; GBA 2009/019/4 i; transverse section. E. Margarophyllia cf. capitata (Münster, 1841); GBA 2009/019/2c; transverse section. F. Thamnomargarosmilia aff. prima Melnikova, 1996; GBA 1995/2/1/2f, c; transverse sections showing budding with lamellar linkages between centres (F1), and a typical circular shape of adult corallite (F2) with a new one growing laterally. G, H. Margarosmilia adhios sp. nov. G. GBA 2009/019/18a; a fragment of transverse section (G1) of a corallite with traces of microstructure; longitudinal section (G2) of corallite showing small dissepiments. H. GBA 2009/019/19a, c; transverse section of phaceloid corallum (H1); a section of the corallite at a preliminary stage of sub−symmetric division (H2).