Platygyra daedalea ( Ellis and Solander, 1786 )

Stolarski, Jarosław, 2003, Three-dimensional micro- and nanostructural characteristics of the scleractinian coral skeleton: A biocalcification proxy, Acta Palaeontologica Polonica 48 (4), pp. 497-530 : 510

Platygyra daedalea ( Ellis and Solander, 1786)

A transversely sectioned septum of P. daedalea shows in TLM similar zones as G. fascicularis , i.e., brownish dRAF (or dCRA if well differentiated) bordered with ca. 10 µm wide zone of TD fibers that further show regular and dense alternations (ca. every 3–5 µm) of thin darker, and slightly thicker, lighter layers ( Fig. 11A, D ). These alternations are very prominent in TLM, however, darker layers exhibit very weak but recognizable greenish fluorescence in MFM ( Fig. 11C ). Components of the dRAF zone show much brighter (however not as bright as in G.fasciularis ) green−yellow fluorescence ( Fig. 11B ). Dark brown (in TLM) filaments of endolithic organisms (red arrows in Fig. 11A ) show bright yellow−green fluoresece in MFM. Scanning electron micrographs of polished and lightly−etched section of the same septal fragment illustrated in Fig. 11D , show oval structures with negative etching relief (dCRA). Outwards from dCRA occurs ca. 10 µm wide zone of fibers. It borders on to the thick zone of TD fibers that are regularly tapered every 3–5 µm or show regular fiber discontinuities between successive layers ( Fig. 11E ).

Figures

Fig. 11. Platygyra daedalea (Ellis and Solander, 1786); ZPALH.23/8 (originally NMNH A.G. Humes collection. Acc. number 274378). Recent, 25 m, north of Ankazo−beravina, near Nosy Be, Madagaskar, August 24, 1967. A. Transverse polished section of septum in TLM; note brownish “calcification centers” (dRAF), regular growth increments of fibers (e.g., in encircled area), and dark brown regions (red arrows) of filaments of endolithic organisms (most likely algae, fungi). B. The same septal fragment as A, stained with acridine orange in MFM view; dRAF exhibit very light, green−yellow fluorescence; higher magnifications (C) show delicate greenish bands matching organic components trapped between successive growth increments of fibers (white arrows). D. Transverse polished section of septum in TLM; dRAF in lower right corner; regular growth increments of fibers (TD) are emphasized by levels of brownish bands. E. SEM micrograph of transverse polished and etched section of septum; fibers adjacent to row of dRAF (“calcification centers”) taper regularly at ca. 3 µm matching brownish bands in D.