Philippine Journal of Science
151 (S1): 61-72, Marine Botany
ISSN 0031 – 7683
Date Received: 07 Jun 2021
Molecular Phylogeny of Three Unarmored
Dinoflagellates from Masinloc Bay, Zambales,
Central Luzon, with a Description of the Morphology
of Gymnodinium catenatum H.W.Graham
Garry A. Benico1* and Rhodora V. Azanza2
1Department of Biological Sciences, College of Science
Central Luzon State University Science City of Muñoz, Nueva Ecija 3120 Philippines
2The Marine Science Institute, University of the Philippines Diliman
Quezon City 1100 Philippines
*Corresponding author: gabenico@clsu.edu.ph
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Benico G, Azanza R. 2022. Molecular Phylogeny of Three Unarmored Dinoflagellates from Masinloc Bay, Zambales, Central Luzon, with a
Description of the Morphology of Gymnodinium catenatum H.W.Graham. Philipp J Sci 151(S1): 61–72. https://doi.org/10.56899/151.S1.04
ABSTRACT
Unambiguous identification of unarmored dinoflagellates is important in distinguishing toxic from non-toxic species occurring in the coastal waters of the Philippines. In this study, molecular phylogeny inferred from rDNA sequences of Gymnodinium catenatum, Gymnodinium impudicum, and Akashiwo sanguinea – collected from Masinloc Bay, Zambales, Central Luzon – is reported for the first time. Morphology of G. catenatum was critically examined using light and confocal laser scanning microscopy. The three unarmored dinoflagellates were identified as G. catenatum, G. impudicum, and A. sanguinea based on their phylogenetic positions inferred from LSU and SSU rDNA. Both G. catenatum and G. impudicum grouped in a well-supported clade of Gymnodinium sensu stricto, which includes other genera of unarmored dinoflagellates, confirming the polyphyly of the clade. Akashiwo sanguinea separated into four subclades, which is similar to previous reports – with our strain grouping with sequences from Malaysia, Singapore, and China. Cellular characteristics of our G. catenatum are congruent with earlier reports particularly its long chain-forming habit (up to 64 cells) and large cell size (44.6–63.3 µm long). Our result is the first verified record of G. impudicum and A. sanguinea in the Philippines, and the first record of G. catenatum as another highly toxic dinoflagellate species occurring in Masinloc Bay.