Free-living marine planktonic unarmoured dinoflagellates from the Gulf of Mexico and the Mexican Pacific

Abstract

The so-called unarmoured dinoflagellates are not a “natural” (phylogenetic) group but they lack thecal plates, share fragility and possess relatively few morphological characters that can be positively identified. This study depicts the species composition of unarmoured dinoflagellates collected from sites along the coasts of the Gulf of Mexico and the Mexican Pacific and includes their descriptions and illustrations. We identified a total of 25 species belonging to 13 genera and six families that were studied through various techniques using light and scanning electron microscopy. Seven new records for the Mexican Pacific are annotated here that include

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“…Systematic studies mostly require living samples and/or particular techniques and protocols such as use of scanning/transmission electron microscopy, molecular sequencing, etc. (Larsen & Nguyen, 2004;Escobar-Morales & Hernández-Becerril, 2015).…”

“…Microscopic studies were made on unfixed-living and fixed material with a Nikon TE2000U inverted microscope at X400 magnification. Identification of Polykrikos hartmannii was performed on living samples and based on general characteristics such as shape, size, motility of cells, colour of chloroplasts (Hulburt, 1957;Steidinger & Tangen, 1995;Escobar-Morales & Hernández-Becerril, 2015;Hoppenrath et al, 2010). Identified taxa were controlled with the check-lists (Koray, 2001;Balkıs, 2004) for the distribution in Turkish seas and also with current literature.…”

“…Although the Mediterranean Sea represents only a small percentage of the world's oceans, contains nearly 43 % of the world's marine dinoflagellates species, including c. 88% of the dinoflagellates genera (Gomez, 2006). There are two main groups of dinoflagellates: the thecate (or armoured) forms that have a series of relative rigid thecal plates of different sizes and shapes and the so-called unarmoured (or naked) forms that lack of these structures and are generally more fragile (Escobar-Morales & Hernández-Becerril, 2015).…”

“…First description of the species was given by Zimmermann (1930) and then, it was re-described by Matsuoka and Fukuyo (1986) as the species, Pheopolykrikos hartmannii, which was determined as synonym of Polykrikos hartmannii (Escobar-Morales & Hernández-Becerril, 2015). Polykrikos hartmannii is currently accepted name, taxonomically (Guiry & Guiry, 2017 (Mizushima, Matsuoka & Fukuyo, 2007;D'Costa, Anil, Patil, Hegde, D'Silva & Chourasia 2008) and the western Pacific including Korea, Japan and China (Wang, Matsuoka, Qi, Chen & Lu, 2004;Shin et al, 2010).…”

Ichthyotoxicity of the Dinoflagellate Karlodinium veneficum in Response to Changes in Seawater pH

“…The marine dinoflagellate Karlodinium veneficum has a global distribution and produces powerful lytic karlotoxins that have been associated with extensive fish kills (Mooney et al, 2010;Place et al, 2012;Adolf et al, 2015;Escobar-Morales and Hernández-Becerril, 2015). Emerging evidence suggests that these toxins are primarily produced to facilitate feeding by prey immobilization (Sheng et al, 2010).…”