Virgularia sp.

Chen, Jei-Ying & Williams, Gary C., 2015, X-ray Microanalysis and the Chemical Elemental Composition of Gorgonian and Pennatulacean Axial Structures (Anthozoa, Octocorallia), Proceedings of the California Academy of Sciences 62 (16), pp. 399-415 : 406-410

Virgularia sp.

Figures 9A–B , 10A–D .

Like the observations in the previous specimens, some degree of fluctuations and shift of linescans of carbon (in purple, 20.42 wt%), oxygen (in light green, 44.95 wt%), calcium (in green, 29.35 wt%) and magnesium (in dark green, 2.57 wt%) are found on Virgularia sp. as well ( Figure 10B ); they are mostly found along the central axis region, which may be implied by the BSE image that shows the darker contrast region in the central core of the axis. The fluctuated patterns are consistent among the four elements, thus a clear grouped relationship can be seen when zooming to higher magnification in Fig 10B . The linescan patterns of fluorine (in pink, 1.60 wt%) and the four remaining trace elements sodium (in blue, 0.55 wt%), sulfur (in sky blue, 0.30 wt%), chlorine (in red, 0.07 wt%) and REE ytterbium (in orange, 0.19 wt%) are similar in nature, with an evenly displayed appearance along the linescan section. Table 5 displays the weight percentage value of all nine identified elements.

TABLE 5. EDS results of the sum spectrum for sea pen Virgularia sp. axial cross-section surface from Figure 10A . (All results are in weight%)

Spectrum ਖ F Na Mg S Cl Ca Yb Total Sum Spectrum

20.42 44.95 1.6 0.55 2.57 0.3 0.07 29.35 0.19 100 (Weight%)

A B

408 PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES Series 4, Volume 62, Part 2, No. 16

410 PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES Series 4, Volume 62, Part 2, No. 16

Figures

FIGURE 9. Scanning electron microscope (SEM) micrographs of a cross-sectional view of a sea pen Virgularia sp. axial skeleton. (A) In this secondary electron (SE) image a great degree of the radiating patterns well-arranged across the whole axial surface can be observed, such character is also used in the morphological phylogenetic studies of the calcaxonian gorgonians and sea pens. Scale bar = 200 μm. (B) Back-scattered electron (BSE) image. There seemed to be some chemical composition contrast appearing darker in the central portion of the axis, though several between-site area scans were performed, yet no differences in chemical composition can be found (data not shown); however, the between-site changes on weight percentage value of some elements can be detected as shown in the next Figure 10B. Scale bar = 200 μm.

FIGURE 10. Energy dispersive spectrometer (EDS) linescan dataset. (A) EDS linescan site of interest BSE image in a cross-sectional view of a sea pen Virgularia sp. axial skeleton acquired by INCA Energy software using same region as Figure 9, horizontal linescan through the middle of the axis was applied for EDS analysis to examine the distribution of elements along the line. (B) Element linescan result displaying grouped linescans as colored: carbon (purple), oxygen (bright green), fluorine (pink), sodium (blue), magnesium (green), sulfur (teal), chlorine (red), calcium (light green), ytterbium (gold). (C) Sum spectrum of the linescan. Scale bar = 1 mm. (D) Bar chart of the quantitative results from the sum spectrum.