The first report of Vulcanodinium rugosum (Dinophyceae) from the South China Sea with a focus on the life cycle

An individual non-motile (NM) cell was isolated from a surface sediment sample collected in Guangxi, China and subsequently established as a dinoflagellate strain in culture. The motile cells are 22.532.5 mu m long and 20.030.0 mu m wide, with a plate formula of Po, X, 4', 3a, 7, 6c, 5(?)s, 5', 2, fitting the description of Vulcanodinium rugosum. The Chinese strain shares 99.8%, 97.4% and 96.7% similarity (LSU sequence) with those from Australasia, France and Japan. Asexual division of V. rugosum takes place either in the thecate motile stage or within a NM division cell. Motile cells divided by binary fission inside the parent cell and transformed to NM division cells within 24 h. The NM cell underwent one to three consecutive divisions within the parent wall. The divisions were not always synchronous and neither was the release of motile cells from the NM cells. It generally took 4 to 6 days for the NM cells to complete one division. NM cells survived for 1 month at 4 degrees C in the dark, suggesting that they might play an important role in species dispersal. A novel pinnatoxin was detected at 20 pg cell-1 and no other known pinnatoxins (AG) were detected.