ASGP (2016), vol. 86: 1–16

MICROSTRUCTURAL EVIDENCE OF THE STYLOPHYLLID AFFINITY OF THE GENUS CYATHOPHORA (SCLERACTINIA, MESOZOIC)

Elżbieta MORYCOWA (1) & Ewa RONIEWICZ (2)
1) Institute of Geological Sciences, Jagiellonian University, Oleandry 2a, 30-630 Kraków, Poland; e-mail: elzbieta.moryc at uj.edu.pl
2) Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 01-818 Warszawa, Poland; e-mail: eron at twarda.pan.pl

Morycowa, E. & Roniewicz, E., 2016. Microstructural evidence of the stylophyllid affinity of the genus Cyathophora (Scleractinia, Mesozoic). Annales Societatis Geologorum Poloniae, 86: 1–16.

Abstract: The genus Cyathophora Michelin, 1843 (Cyathophoridae) is removed from the suborder Stylinina Alloiteau, 1952 and transferred to the Stylophyllina Beauvais, 1980. Morphologically, it differs from stylinine corals in that rudimentary septa are developed in the form of ridges or spines on the wall and may continue onto the endothecal elements as amplexoid septa. Relics of primary aragonite microstructure, preserved in silicified colonies of Cyathophora steinmanni Fritzsche, 1924 (Barremian–early Aptian) and in a calcified colony of C. richardi Michelin, 1843 (middle Oxfordian), indicate a non-trabecular structure of their skeletons. The sclerenchyme of radial elements is differentiated into fascicles of fibres, and in the form of fascicles or a non-differentiated layer of fibres, it continues as the upper part of endothecal elements and as the incremental layers of the wall. A micro-lamellation of the skeleton corresponds to the accretionary mode of skeleton growth found in Recent corals. A similarity between the septal microstructure of Cyathophora and that of the stylophyllid genera, the Triassic Anthostylis Roniewicz, 1989 and the Triassic–Early Jurassic Stylophyllopsis Frech, 1890, is interpreted as a result of their being phylogenetically related. The microstructure of the Jurassic Stylina gaulardi Michelin, 1843 has been considered for purposes of comparison. The systematics of the genus Cyathophora is formally revised with C. richardi Michelin reinstated as the type species.

Manuscript received 18 December 2014, accepted 25 June 2015