CHARACTERIZATION OF OSTREOPSIS AND COOLIA (DINOPHYCEAE) ISOLATES IN THE WESTERN MEDITERRANEAN SEA BASED ON MORPHOLOGY, TOXICITY AND INTERNAL TRANSCRIBED SPACER 5.8S rDNA SEQUENCES¹

Abstract

Several isolates of epiphytic dinoflagellates belonging to the genera Ostreopsis Schmidt and Coolia Meunier from the western Mediterranean Sea were examined by LM and EM, toxicity assays, and internal transcribed spacer (ITS) regions of nuclear rDNA, and 5.8S rDNA were sequenced. Morphological comparisons based on the analyses of cell shape, size, thecal plates, and surface ornamentation revealed two distinct species in the western Mediterranean: O. cf. siamensis Schmidt from the Catalan, Andalusian, and Sicilian coasts and O. ovata Fukuyo from the Ligurian coast, southern Tyrrhenian Sea, and Balearic Islands. Both Ostreopsis species were toxic; however, no differences in toxicity were detected between the two Ostreopsis species. Coolia monotis Meunier was nontoxic. The morphological studies were supported by phylogenetic analyses; all western Mediterranean isolates of O. cf. siamensis showed ITS and 5.8S rDNA sequences identical to each other and so did those of O. ovata, whereas high genetic diversity was detected between the western Mediterranean and Asian isolates of O. ovata. The nucleotide sequence analyses of the C. monotis strains showed that all C. monotis isolates from Europe formed a homogeneous clade. Further, the genetic diversity was high between the European and Asian C. monotis isolates. In this study, genetic markers combined with morphology and toxicity analyses was useful in the taxonomic and phylogenetic studies of the Ostreopsidaceae in a temperate area.

Morphological and genetic characterization of benthic dinoflagellates of the generaCoolia,OstreopsisandProrocentrumfrom the south-eastern Bay of Biscay

“…Two main clades of Coolia were consistently well supported in the phylogenetic tree, one including the strains of C. monotis plus C. malayensis as sister taxon, and the other the strains of C. canariensis. In agreement with the results of Penna et al (2005), only slight geographical differences can be observed among the different strains from the Mediterranean and the local isolates of C. monotis, which appear to belong to a single evolutionary lineage, whereas the New Zealand strain constitutes a genetically distinct entity described as Coolia malayensis (Leaw et al, 2010). Similar relationships were inferred by Fraga et al (2008) who found three different lineages within selected strains of the genus Coolia, one of them including strains of C. canariensis, a second with C. monotis from Indonesia and Belize and a third containing two sister groups, one corresponding to C. monotis from European localities and the other to C. monotis and C. malayensis from New Zealand, Malaysia and Florida.…”

“…The tabulation pattern of C. canariensis is very similar to that of C. areolata, but thecal ornamentation allows differentiation of the two species. Cell sizes of C. monotis strains fall within published values (Penna et al, 2005;Dolapsakis et al, 2006). The strains have morphological features similar to previous descriptions of the species, although with some differences from Meunier's (1919) original description and other later descriptions, especially regarding some plates of the epitheca.…”

“…The strains have morphological features similar to previous descriptions of the species, although with some differences from Meunier's (1919) original description and other later descriptions, especially regarding some plates of the epitheca. Plates 6 00 and 5 00 are elongated in the original description and the suture between them runs in a nearly dorso-ventral direction, while in our strains it runs to the right side, resulting in a wider, not elongated 6 00 plate and a smaller 5 00 , similar to other later descriptions (Fukuyo, 1981;Penna et al, 2005;Dolapsakis et al, 2006). Differences are also found in plates 1 00 and 2 00 .…”

“…Taking into account cell shape and dimensions, thecal pores and Po size in different species of the genus Ostreopsis, the local strains best fit the Mediterranean O. cf. siamensis strains given by Penna et al (2005) and Aligizaki & Nikolaidis (2006), an affinity confirmed by the molecular analysis. The morphology of the local strains of Ostreopsis also fits the description given by Fukuyo (1981) for O. siamensis, except in cell size (smaller in our strains), and differs from that given by Faust et al (1996) and Chang et al (2000) in having only one size of thecal pores.…”

“…siamensis and Prorocentrum lima. Coolia monotis is frequently found both in temperate as well as in tropical areas (Meunier, 1919;Penna et al, 2005;Aligizaki & Nikolaidis, 2006;Dolopsakis et al, 2006) and the P. lima complex has also been reported from temperate areas (e.g. Faust, 1991;Bravo et al, 2001;Levasseur et al, 2003;Foden et al, 2005;Maranda et al, 2007;Aligizaki et al, 2009) in addition to tropical ones.…”