Xa. Mu et R. Riding, Skeletal ultrastructure of the calcified red alga Galaxaura oblongata, Hainan Island, China, REV PALAE P, 104(3-4), 1999, pp. 205-212
Aragonite calcification in the red alga Galaxaura oblongata (Ellis et Solan
der) Lamouroux (Chaetangiaceae, Nemaliales) from southern China, occurs at
three sites in the cortex: (1) intercellular spaces (ICS); (2) the cell wal
l, and (3) the inner surface of the cortex. The ICS is the principal site o
f calcification and contains aragonite mainly in the form of equidimensiona
l granules similar to 1-2 mu m in size, although needle-like crystals up to
3 mu m in length are also present locally Granules range from densely to l
oosely packed. A dense and even layer peripheral to the ICS is interpreted
to represent calcification of the cell wall. Coarser radial clumps of elong
ate crystals, forming a thin discontinuous layer on the inner surface of th
e cortex, resemble a cement fringe facing into the medulla, but form during
the life of the alga. Calcification in these specimens shows similarities,
and differences, to both coralline red algae, in which calcification is li
mited to the cell wall, and halimedacean green algae in which it is limited
to the ICS. Some members of the Palaeozoic family Moniliporellaceae show s
imilarities in their skeletal organization to Galaxaura. (C) 1999 Elsevier
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