Gonyaulax sp.

Lewis, Jane, Taylor, Joe D., Neale, Klaire & Leroy, Suzanne A. G., 2018, Expanding known dinoflagellate distributions: investigations of slurry cultures from Caspian Sea sediment, Botanica Marina (Warsaw, Poland) 61 (1), pp. 21-31 : 27

Gonyaulax sp. ( Figures 7–10 )

Motile cells were brownish-yellow in colour, 35–40 µm long and 25–30 µm wide. Cells had a conical epitheca with a pronounced apical horn arising from distinct shoulders ( Figures 7–9 ). The hypotheca was slightly flattened with a long (5–8 µm) single antapical horn. The wide median cingulum was offset by two cingulum widths. Thecal plates were strongly reticulate ( Figure 10 ). This poorly growing strain did not survive to sequencing so observations as to identity can only be made on the basis of light microscopy. The cells can be compared to Gonyaulax digitale Kofoid and Gonyaulax elongata (Reid) Ellegaard, Daugbjerg, Rochon, Lewis et Harding for which cyst-theca relationships have been described ( Lewis et al. 2001, Ellegaard et al. 2003). They resemble most closely the former with the exception of the single prominent antapical spine – no specimens being seen with two or more spines as is diagnostic for this species. Gonyaulax elongata is characterised by a single antapical flange but has a rather less pronounced apical horn with only weak shoulders in contrast to the cells observed here. Neither have either of these cyst types been recorded from Caspian Sea sediment. Table 1 shows there are several other gonyaulacoid cysts recorded in the sediment – Spiniferites belerius Reid , Spiniferites cruciformis Wall et Dale and Caspidinium rugosum Marret. From this study, it is not possible to determine which, if any, of these are linked to this Gonyaulax . Comparison to some 25 other described Gonyaulax species does not yield any clear affinities. At this point, we do not consider we have sufficient information to fully describe this species and prefer to wait to provide a description that would also include the cyst stage.

Figures

Figures 2–31: Light micrographs of Caspian Sea dinoflagellates grown in culture from sediments. (2–6) Gonyaulax baltica, culture CS-ST1-005. (2) Lateral view of cell showing cingulum offset. (3) Dorsal view of cell showing general shape and wide cingulum. (4) Antapical view of cell showing broad sulcus. (5) Ecdysed cell showing antapical spines. (6) Hypotheca of cell showing plate reticulation, smooth sulcus and intra plate growth bands. (7–10) Gonyaulax sp., culture CS-ST2-001. (7) Lateral view of cell showing general shape, cingulum offset, apical horn and antapical spine. (8) Ventral view of cell showing broad offset cingulum. (9) Dorsal view of cell in outline showing pronounced apical horn and definite shoulders. (10) Ecdysed theca showing solid antapical spine and heavy plate reticulation. (11–14) Gymnodinium aureolum. (11–13) Culture CS-ST7-009. (14) Culture A3. (11) Cell showing overall shape, central nucleus and radiating chloroplasts. (12) Ventral view of cell showing sulcal-cingulum arrangement. (13) Dorsal view of cell. (14) Cells in duplet. (15–20) Kryptoperidinium foliaceum. (15 and 19) Culture CS-ST1-007. (16 and 18) Culture CS-ST1-001. (17 and 20) Culture A6. (15) Ventral view of cell showing leaf-like curvature, central nucleus, median cingulum and eyespot. (16) Lateral view of cell showing dorsoventral flattening and eyespot. (17) Theca stained with trypan blue. (18) Cysts in ventral view. (19) Cyst in lateral view. (20) Cysts in mucoid capsule. (21–25) Lingulodinium polyedra. (21 and 23) Culture CS-ST1-002. (22) Culture CS-ST1-004. (25) Culture CS-ST1-003. (21) Ventral view of cell showing cingulum offset and first apical plate. (22) Dorsal view of cell showing horse-shoe shaped nucleus. (23) Ecdysed hypotheca showing distinctive polyhedral shape and plate reticulation. (24) Squashed cell showing thecal plates. (25) Cyst from Station 1 sediment. (26–28) Scrippsiella acuminata. (26) Culture CS-ST2-006. (27–28) Culture D10. (26) Outline view of cell. (27) Outline view of cell. (28) Cyst formed in culture. (29–30) Woloszynskia sp. (29) Culture D3 showing cell with eyespot. (30) Cell showing general outline from culture D4. (31) Impagidinium caspienense from palynological preparation (core CS03/1 at 32 cm) showing archeopyle. Scale bars = 10 µm.