Morphology and molecular phylogeny of Ostreopsis cf. ovata and O. lenticularis (Dinophyceae) from Hainan Island, South China Sea

Abstract

SUMMARY The genus Ostreopsis contains benthic and potentially toxic species that are distributed in tropical and temperate regions. In this study, we present the first report of observations of Ostreopsis cf. ovata and O. lenticularis in Chinese waters. Isolates were characterized morphologically based on LM and SEM, and phylogenetic analyses were conducted by sequencing the LSU rDNA (D1–D3), ITS region (ITS1‐5.8S‐ITS2) and SSU rDNA. The morphology of O. cf. ovata Hainan strains was similar to the original description of O. ovata, despite differences in cell size. The morphology of O. lenticularis Hainan strains was similar to the original description, although both deviations of cell dimensions and different kinds of thecal pores were observed. The plate formula for the Ostreopsis Hainan strains was arranged in Kofoid's system tabulation of Po, 3′, 7′′, Vp, Rp, 1p, 5′′′, 2′′′′. The O. cf. ovata and O. lenticularis Hainan strains showed close relationships with strains collected from the Pacific Ocean based on the sequences of both LSU rDNA and ITS region. The genetic differences (p‐distances) of SSU rDNA sequences of the Ostreopsis cf. ovata Hainan strain were 0.0096 and 0.0447 different from those of a Malaysian strain and a South Korean strain, respectively. This work identifies the first occurrence of Ostreopsis with the morphology and phylogeny of Hainan strains in Chinese waters.

Ostreopsis cf. ovata (Dinophyceae) Molecular Phylogeny, Morphology, and Detection of Ovatoxins in Strains and Field Samples from Brazil

“…Phylogenetic reconstructions based on D1-D3 region included three new sequences from the current study and other 75 sequences retrieved from GenBank, totaling 78 OTUs and 720 aligned nucleotides. The overall tree topology was similar to that observed with ITS and D8-D10 sequences in the current study, and with D1-D3 sequences by other authors [8,9,33] (Figure 6). There are no D1-D3 sequences available for Ostreopsis sp.…”

“…The relationships among Ostreopsis species and Ostreopsis cf. ovata clades were congruent with those observed in the literature [8,9,[14][15][16]33]. Hence, only the topologies of the BI phylogenetic trees are presented in the manuscript (Figures 5-7 for ITS, D1-D3 and D8-D10, respectively).…”

“…It is recognized that O. cf. ovata cell shape and size may exhibit great variability and overlap with other species in the genus [10,12,33]. In the current study, cell dimensions among various O. cf.…”

“…ovata subclade A together with sequences of strains from the Mediterranean Sea, the NE Atlantic (Canary Island and Portugal) as well as the SE Atlantic (Rio de Janeiro, Bahia and São Paulo in Brazil) and Japan. This is the Mediterranean/Atlantic/Pacific (AMP) clade as described by Zhang et al [33] and Tibiriçá et al [30]. Its sister subclade (B) contained three sequences, including strain UNR-10 isolated from the Brazilian Northeast coast, strain VGO614 from Madeira Island (Portugal) and strain KC17 from the Mediterranean Sea (Greece) ( Figure 5).…”

“…Moreover, in these cells of strain UNR-10 ( Figure 2E-F) plate 2 extended between plates 2" and 3 , being longer than the APC plate, as already observed for other specimens of the O. cf. ovata phylogenetic clade by Penna et al [10], Zhang et al [33] and Tibiriçá et al [30]. In the observed cells of strain VGO614 plate 2 did not extend between plates 2" and 3 .…”