Amphidinium stirisquamtum sp. nov. (Dinophyceae), a new marine sand-dwelling dinoflagellate with a novel type of body scale

Abstract

Amphidinium species are amongst the most abundant benthic dinoflagellates in marine intertidal sandy ecosystems. Some of them produce a variety of bioactive compounds that have both harmful effects and pharmaceutical potential. In this study, Amphidinium cells were isolated from intertidal sand collected from the East China Sea. The two strains established were subjected to detailed examination by light, and scanning and transmission electron microscopy. The vegetative cells had a minute, irregular, and triangular-shaped epicone deflected to the left, thus fitting the description of Amphidinium sensu stricto. These strains are distinguished from other Amphidinium species by combination characteristics: (1) longitudinal flagellum inserted in the lower third of the cell; (2) icicle-shaped scales, 276 ± 17 nm in length, on the cell body surface; (3) asymmetrical hypocone with the left side longer than the right; and (4) presence of immotile cells. Therefore, they are described here as Amphidinium stirisquamtum sp. nov. The molecular tree inferred from small subunit rRNA, large subunit rRNA, and internal transcribed spacer-5.8S sequences revealed that A. stirisquamtum is grouped together with the type species of Amphidinium, A. operculatum, in a fully supported clade, but is distantly related to other Amphidinium species bearing body scale. Live A. stirisquamtum cells greatly affected the survival of rotifers and brine shrimp, their primary grazers, making them more susceptible to predation by the higher tropic level consumers in the food web. This will increase the risk of introducing toxicity, and consequently, the bioaccumulation of toxins through marine food webs.

Morphological and Molecular Characterization of the Benthic Dinoflagellate Amphidinium from Coastal Waters of Mexico

“…Unfortunately, without observation under transmission electron microscopy (TEM), scales located outside the plasma membrane could not be distinguished. In scale-bearing Amphidinium species, scales were not visible via SEM because they were tiny; e.g., only 136.4 × 91.0 × 81.8 nm in A. cupulatisquama Tamura & Horiguchi [46], 64.8-68.4 × 48.5-49.3 × 12.6-18.4 nm in two unidentified Amphidinium strains closely related to A. carterae [47], and 276 ± 17 nm in A. stirisquamtum Z. Luo, Na Wang & H. Gu [48].…”

Five phototrophic <italic>Scrippsiella</italic> species lacking mixotrophic ability and the extended prey spectrum of <italic>Scrippsiella acuminata</italic> (Thoracosphaerales, Dinophyceae)

“…Dinoflagellates are ubiquitous protists in marine environments (Luo et al 2021, Morquecho et al 2022, and often form red tides or harmful algal blooms that can cause human diseases and massive mortality in shellfish, finfish, and mammals (Shumway 1990, Hallegraeff 1992, Flewelling et al 2005, Jeong et al 2017, Sakamoto et al 2021. The trophic modes, growth and ingestion rates, and mortality rates due to predation of dinoflagellate species should be investigated to understand and predict the outbreak of dinoflagellate red tides (Franklin et al 2006.…”

Primary production by phytoplankton in the territorial seas of the Republic of Korea

“…Oceans are one of the largest storages of carbon dioxide (CO 2 ) on the planet and play a major role in the global carbon cycle by absorbing approximately 30% of atmospheric CO 2 each year (Raven and Falkowski 1999). Although both pelagic and benthic communities of primary producers are responsible for primary production (PP) in the ocean, approximately half of the global annual net PP is produced by marine phytoplankton (Field et al 1998, Spector and Edward 2020, Luo et al 2021. This primary source of energy supports the entire marine biomass through food webs (Turner 2004).…”