Loeblich, Alfred R., III2024-06-062024-06-0619829455212https://hdl.handle.net/10657/17538Cultures of Coolia monotis, Gambierdiscus toxicus and Ostreopsis ovata were initiated fron intertidal areas from the Caribbean Sea and G. toxicus from the Florida Keys. This is the first report of these three species from the Caribbean Sea; overwintering of G. toxicus in the Florida Keys is also documented. Photomicrography of thecae and scanning electron microscopy of cells of O. ovata revealed the following thecal plate tabulation: 1pp, 4', 6'', 6c, 8s, 5''', and 2''''. Variations in thecal plate numbers and tehcal fission lines are reported for O. ovata. Thecal plate assignments, based on interpretations of plate homologies, demonstrated gonyaulocoid affinities of these three genera and a sufficiently close relationship among them to place them in the family Ostreopsidaceae. Transmission electron micrographs of each of the three species revealed a unique cytoplasmic feature: vesicle-bound, spirally coiled, fibrous material. An astral aggregation of these vesicles (=pusule) occurred near the sulcal region. The tethered habit of these species is discussed in relation to the spiral bodies. Bioassays for toxicity in C. monotis and O. ovata and G. toxicus (Florida isolate) revealed the presence of toxic activity only in the lipid soluble fraction of G. toxicus. The minimal amount of residue that was lethal in less than 24h was 101 [micrograms] per g of mouse tissue, or 510 mouse units per 10[superscript 6] cells. Sterols were analysed by gas chromatography-mass spectrometry. For C. monotis and O. ovata, only cholesterol and dinosterol were detected (ration 2:1). An additional sterol, 24-methylcholesterol, was present in G. toxicus. The relative percentage of sterols in G. toxicus were 47% cholesterol, 20% dinosterol and 33% 24-methylcholesterol. Qualitative and quantitative similarities in the sterol fractions from members of these genera suggest they form a natural group (family Ostreopsidaceae). The sterol pattern of this family closely resembles that r eported for members of the family Gonyaulacaceae; confirming the conclusion, from morphological studies, that they are close relatives.application/pdfenThis item is protected by copyright but is made available here under a claim of fair use (17 U.S.C. Section 107) for non-profit research and educational purposes. Users of this work assume the responsibility for determining copyright status prior to reusing, publishing, or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires express permission of the copyright holder.DinoflagellatesThesisreformatted digital