Analyses
Samples from Viet Nam were examined under a Leica DMLB (Solms, Germany)
microscope using phase-contrast (PC), differential interference contrast
(DIC), and epifluorescence (Epi) optics. In order to visualize thecal
plate patterns, dinoflagellate cells were stained with Calcofluor White
M2R according to Fritz and Triemer (1985). The digital camera Olympus
DP71 was used for light and epifluorescence microphotography. Microscopy
study of the samples from the Persian Gulf was conducted at the
Institute for Evolutionary Ecology of the NAS of Ukraine using an
Olympus BX51 light microscope with UPlanFLN 40x/0.67 and UPlanFLN
100x/1.30 (Oil) lenses. Dinoflagellates were examined in transmitted
light, DIC, and in an epifluorescence mode with preliminary staining of
cells using Calcofluor White M2R (Fritz and Triemer, 1985). Pictures
were taken with a Canon EOS 5D Mark II digital camera.
For scanning electron microscope (SEM) examination, cells ofProtoperidinium were isolated by Pasteur pipettes from preserved
samples under a stereomicroscope and placed on a 5 µm carbon membrane
filter, rinsed with distilled water, dehydrated through an ethanol
series (15, 30, 50, 70, 90, 99, and 100) of absolute ethanol, and
air-dried. The filter was mounted onto an aluminum stub with carbon tape
and finally coated with gold. The stubs were studied under a Hitachi
FE-SEM (Field Emission Scanning Electron Microscope) model S4800 at the
Institute of Materials Science, Viet Nam Academy of Science and
Technology (Ha Noi, Viet Nam).
Thecal plate terminology follows the Kofoid tabulation system (Kofoid
1909). The identification of Protoperidinium species, as well as
the use of biometric terminology and abbreviations, was based on
Schiller (1937), Graham (1942), Taylor (1976), Abé (1981), Balech (1974,
1988), Okolodkov (2008), and Phan-Tan et al. (2017). The taxonomic
position was specified in accordance with the classification of
dinoflagellates by Fensome et al. (1993), taking into account Balech
(1988).