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A new species of Dinoflagellata—Protoperidinium euxinum Krachmalny sp. nov. (Protoperidiniaceae, Peridiniales) was described from the plankton of Odessa Bay (Black Sea). The species is morphologically close to P. steinii, P. mediterraneum and P. joergensenii. It differs from the listed species in elongated pentagonal body shape, conical epitheca with straight or concave lateral sides, inverse trapeziform hypotheca, and asymmetrical, laterally compressed plate 2a. Dimensions: 73.3–99.0 µm in length and 38.8–51.6 µm in width. Pictures and photomicrographs of the novel species are presented, along with detailed description and discussion.

Protoperidinium euxinum Krachmalny sp. nov. (Fig. 2, A–E) Division Dinoflagellata (Butschli 1885) Fensome et al. 1993. Class Dinophyceae Pascher 1914. Order Peridiniales Haeckel 1894. Family Protoperidiniaceae Balech 1988 nom. cons. Genus Protoperidinium Bergh 1881. Diagnosis:— Cells medium-sized (length 88.6±7.2 µm, min. 73.3 µm, max. 99.0 µm; width 45.4±4.0 µm, min. 38.8 µm, max. 51,6 µm; n=20), pentagonal, elongated, slightly compressed dorsoventrally. Epitheca conical, with straight or concave lateral sides, tapers into a narrow and relatively long apical horn. Epitheca larger than the hypotheca, “meta–penta” type. The plate 2a asymmetrical, laterally compressed. Cingulum ascending by about one-half of its height, shallow and bears lists. Hypotheca inverse trapeziform, with large slightly divergent antapical horns bearing wide membranes. Sulcus straight, broad, shallow, slightly invades the epitheca, reaches the antapex. The sulcal area bordered. Thecal surface with fine reticulations and numerous pores. Cells colorless or light brown. Nucleus spherical, located in the center of the epitheca. Holotype:— Fig. 2, A–Е. The specimen on which the illustration is based was collected in the northwestern part of the Black Sea (Odessa Bay) in August 2020, at 46°26′28.25′′N, 30°46′25.52′′E (Fig. 1: MF, Maliy Fontan). Etymology:— The specific epithet was chosen in order to emphasize the locality of this species—the Black Sea, which was called in ancient times “Pontus Euxinus”. Paratype:— The phytoplankton sample was preserved in 4% formaldehyde solution and is stored at the Institute for Evolutionary Ecology of the National Academy of Sciences of Ukraine (Kiev, Ukraine). Ecology and distribution:— Protoperidinium euxinum reaches large numbers in Odessa Bay (northwestern part of the Black Sea, sampling sites are shown in Fig. 1) during the warm period of the year. Water temperature and salinity were 20° C and 18 psu, respectively. Occurs together with Protoperidinium steinii (Jørgensen) Balech and P. mediterraneum (Kofoid) Balech. Description:— Cells of Protoperidinium euxinum are medium-sized (73.3–99.0 µm in length and 38.8–51.6 µm in width), shaped like elongated pentagons (Fig. 2, A–B; Fig. 3, A; Fig. 4, A, B, K), slightly compressed dorsoventrally (Fig. 4, B, E, F, J). The epitheca is conical, with straight or slightly concave lateral sides (Fig. 2, C, D; Fig. 3, B, C; Fig. 4, A–K), tapers into a narrow and relatively long apical horn (Fig. 2, A, B). The apical pore plate (Po) connects with the plate 1’ through a small and narrow plate “x” (Fig. 2, A). The epitheca is larger than the hypotheca, the plate arrangement is “meta–penta”; plates 1’ and 2a are pentagonal (Fig. 2, A, E; Fig. 3, B, D, E; Fig. 4, D, H). The plate 1a is also pentagonal (Fig. 4, G). The plate 2a is asymmetrical, laterally compressed, the length of the suture between plates 1a and 2a is greater than between 3’ and 2a (Fig. 2, E; Fig. 3, E; Fig. 4, H). The plate 3a is hexagonal (Fig. 4, I). The cingulum is ascending by about one-half of its height, shallow, composed of plates C1–C3 and transitional plate “t”, and bears lists with pronounced ribs (Fig. 2, A, B; Fig. 3, B, C; Fig. 4, A). The sulcal area is bordered by lists (Fig. 3, F, G). The sulcus is straight, broad, shallow, slightly invades the epitheca (plate Sa), reaches the antapex, composed of the plates Sa, Sd, Ss, Sm and Sp. The right sulcal plate (Sd), in its apical part, tapers into a very narrow protrusion that overlaps the cingulum and reaches 7’’. The left side of Sd has a well-developed fin (Fn). The plate Ss is covered by the left sulcal list (Ll), which is attached to the plates 1’’’ and 1’’’’ and merges with the left antapical horn. The small median sulcal plate (Sm) and partially the posterior sulcal plate (Sp) are positioned under the fin of the plate Sd (Fig. 2, A; Fig. 3, F; Fig. 4, A). The right sulcal list is underdeveloped. The hypotheca is inverse trapeziform, with large slightly divergent antapical horns bearing membranes; the right horn is more tilted to the side (Fig. 2, A, B; Fig. 3, A, G; Fig. 4, A, K, L). Thecal surface with fine reticulations and numerous pores (Fig. 3, B–E). Cells are colorless or light brown. The nucleus is spherical, located in the center of the epitheca (Fig. 3, H)., Published as part of Krakhmalnyi, Maxim, Krakhmalnyi, Aleksandr & Terenko, Galyna, 2023, Protoperidinium Euxinum (Protoperidiniaceae, Dinophyceae) - A Novel Dinoflagellate Species From The Plankton Of The Black Sea, pp. 229-236 in Phytotaxa 598 (3) on pages 231-232, DOI: 10.11646/phytotaxa.598.3.4, http://zenodo.org/record/7969964, {"references":["Fensome, R. A., Taylor, F. J. R., Norris, G., Sarjeant, W. A. S., Wharton, D. I. & Williams, G. L. (1993) A classification of living and fossil dinoflagellates. Sheridan Press, Hanover, Pennsylvania, 351 pp.","Balech, E. (1988) Los Dinoflagellados del Atlantico Sudoccidental. Publ. Espec. Inst. Esp. de Oceanogr. 1. Madrid, 310 pp.","Bergh, R. S. (1881) Der Organismus der Cilioflagellaten. Eine phylogenetische Studie. Morphologisches Jahrbuch 7: 12 - 288."]}

While diversity of symbiodiniacean dinoflagellates has been a focus of coral reef ecological research, information on the diversity of planktonic dinoflagellates in reef ecosystems remains limited. We used dinoflagellate-targeted PCR to investigate dinoflagellate diversity for a coral reef ecosystem. In the summer of 2007, plankton samples were collected from a lagoon, atoll, and open sea area of Zhubi Reef in the Nansha Islands, South China Sea. Sequencing of dinoflagellate-specific SSU rDNA clone libraries from samples in each of these habitats revealed high diversity and numerous novel dinoflagellate lineages. Gymnodiniales were most abundantly represented in all three water areas. Lagoon assemblages were co-dominated by Syndiniales and Gonyaulacales, the atoll by Gonyaulacales and Peridiniales, and the open sea by Syndiniales and Prorocentrales taxa. Species in the Syndiniales (group II) genus Amoebophrya were represented by eight new sequences and 13 previously described clades and were dominated by species reported to infect Gymnodiniales, Gonyaulacales, Peridiniales, and Prorocentrales taxa. And Amoebophrya were particularly abundant and diverse in the lagoon. Our results suggest that Amoebophrya probably play an important role in regulating dynamics of dinoflagellate assemblages in the Zhubi Reef coral ecosystem. In contrast, the few symbiodiniacean taxa detected occurred only in the open sea, suggesting planktonic aposymbiotic Symbiodiniaceae rarely occur in the reef ecosystem. We demonstrate the usefulness of a dinoflagellate-specific molecular technique for profiling dinoflagellate communities, and uncover diversity and the potential importance of parasitic lineages in a coral reef ecosystem.

A new species of the marine dinophyte genus Heterocapsa Stein is described. Two clonal strains originating from Argentinean coastal waters were examined with light and electron microscopy and LSU and ITS rDNA sequence data were obtained. Heterocapsa claromecoensis sp. nov. is described as a distinctive species with a conical epitheca, a similar sized and rounded hypotheca, a single reticulate chloroplast situated in the periphery of the cell, and a large pyrenoid in the episome, above an ellipsoidal to rounded nucleus in the hyposome. The plate tabulation pattern of Po (pore plate), cp (cover plate), X (X-plate or canal plate), 5ꞌ, 3a, 7ꞌꞌ, 6c, 5s, 5ꞌꞌꞌ, 2ꞌꞌꞌꞌ was as for most other species of Heterocapsa. H. claromecoensis sp. nov. differs from all other species of Heterocapsa by the microarchitecture of two different types of organic body scales, which uniquely were different in height. Phylogenetic trees based on LSU and ITS rDNA sequences placed H. claromecoensis in a separate branch, with a sequence assigned to H. orientalis being the closest match based on LSU rDNA., Sí

The application of scientific names is determined by means of nomenclatural types, and every name has to be typified properly. The concept has limitations for unicellular organisms, because original material frequently consists of drawings and/or inadequately preserved physical material. Peridinium cinctum is an abundant freshwater microalga and variable in both morphology and genotype. Morphological variation is mainly expressed in its epithecal conformation: shape deviations of plates, plate rearrangements, plate fusion and plate additions. Different epithecal conformations were traditionally described as either varieties of P. cinctum or were established as closely related species. Despite this, relations between varieties, ribotypes and geographic locations were oversighted, and the full spectrum of plate variation in P. cinctum is still not well represented. For this reason, we sampled localities in Germany and Poland, from which varieties of P. cinctum were described a century ago. We cultivated monoclonal strains, exhibiting two distinct ITS ribotypes, and assessed their epithecal variation of morphology. Based on ca 2,500 observations of individual cells we report a plethora of both plate and suture deviations from the archetypical epithecal conformation of P. cinctum. Morphologies corresponding to previously described varieties were rare, even at their type localities. Nevertheless, we found morphologies consistent with protologues in four cases and use this material for epitypification. These varieties are now linked to specific DNA sequences, allowing reliable application of scientific names for future studies.

Bauer, Wolfgang, Gottschling, Marc, Keupp, Helmut, Kusber, Wolf-Henning, Mertens, Kenneth N. (2021): Validation of the calcareous dinophyte Wallidinellum (Peridiniales), with notes on the status of fossils in the Code. Phytotaxa 520 (3): 296-300, DOI: 10.11646/phytotaxa.520.3.9, URL: http://dx.doi.org/10.11646/phytotaxa.520.3.9

Sphaerodinium fimbriatum R.H.Thompson (1950: 296). Figure 18 Dimensions: L: 43–45 µm, Td: 34–39 µm. Cell shape: Rounded, oval, dorsoventrally slightly compressed. Plate margins very prominent as fimbriate lists, present in both the epithecal and the hypothecal plates (Fig. 18C). Prominent plate margins, both in the epitheca and the hypotheca, in the form of fimbriate lists. Thecal characteristics: Tabulation, 4ʹ, 4a, 7ʹʹ, 7c, 6s, 6ʹʹʹ, 2ʹʹʹʹ (Figs. 18C and 18D), without apical pore. The plate 1ʹ narrow, elongated, flanked by 2ʹ and 4ʹ plates, and not contacting 1ʹʹ and 7ʹʹ plates (Fig 18C). This character does not appear in the order Peridiniales. The 3ʹ is hexagonal and the four anterior intercalary plates are almost isodiametrical. Cingulum and sulcus: Equatorial cingulum. Narrow sulcus, the Sa plate enters into the epitheca and is in contact with the first and the last pre-cingular plates (Fig. 18C). Ornamentation: The margins of the plates, very prominent, easily visible with light microscopy (Fig. 18B). The margin border present outstanding nodules, such as fimbriae (Fig. 18C). The epithecal plates have a rough texture, without any ornamentation, while each hypothecal plate has a central prominent strip, similar in appearance to the projections of the plate margins (Figs. 18C, E). Localities: Ayapel and Zapatosa in North Colombia. Commentaries: This is the first record of both the genus and the species Sphaerodinium fimbriatum in Colombia. The species is an easily recognizable, due to the shape of the theca and the curved edges when observed with LM. The specimens observed match the original description (Thompson 1951) and are in the size range (Table 10) mentioned in the literature (Carty 2014; Moestrup & Calado 2018). World distribution: Ivory Coast and USA (Moestrup & Calado 2018)., Published as part of Bustamante-Gil, Carolina, Boltovskoy, Andrés, Rengefors, Karin, Tavera, Rosaluz, Amat, Eduardo & Ramírez-Restrepo, Jhon J., 2021, Checklist, new records, and taxonomic annotations of freshwater thecate dinoflagellate (Dinophyceae) in Colombia, pp. 135-167 in Phytotaxa 509 (2) on page 162, DOI: 10.11646/phytotaxa.509.2.1, http://zenodo.org/record/5426087, {"references":["Thompson, R. H. (1951) A new genus and new records of fresh-water Pyrrophyta in the Desmokontae and Dinophyceae. Lloydia 13: 277 - 299.","Carty, S. (2014) Freshwater Dinoflagellates of North America. Cornell University Press, New York, 272 pp. https: // doi. org / 10.7591 / 9780801470370","Moestrup, O. & Calado, A. J. (2018) Susswasserflora von Mitteleuropa. 6. Dinophyceae. B. Budel, G. Gartner, L. Krienitz & M. Schagerl (Eds.) Springer, Berlin, 561 pp. https: // doi. org / 10.1007 / 978 - 3 - 662 - 56269 - 7 _ 7"]}

A study on the freshwater dinoflagellate (Dinophyceae) of Colombia was carried out based on samples from four swamps, nine reservoirs, a small insular lake, and additional specimens deposited in the phycological collection of Universidad de Antioquia, Colombia, and the collection of Universidad de La Plata, Argentina. For most species, detailed morphological descriptions and illustrations are provided. Moreover, the geographical distribution of the species is updated. Durinskia spp., Glochidinium penardiforme, Naiadinium polonicum, Peridiniopsis elpatiewskyi, Peridiniopsis quadridens, and Sphaerodinium fimbriatum, are reported for the first time in Colombia. Furthermore, the correct sulcal plate pattern was determined for Naidinium polonicum which has been misinterpreted in earlier literature.

Dinophyte evolution is essentially inferred from the pattern of thecal plates, and two different labelling systems are used for the important subgroups Gonyaulacales and Peridiniales. The partiform hypotheca of cladopyxidoid dinophytes fits into the morphological concepts of neither group, although they are assigned to the Gonyaulacales. Here, we describe the thecate dinophyte Fensomea setacea, gen. & sp. nov., which has a cladopyxidoid tabulation. The cells displayed a Kofoidean plate formula APC, 3′, 4a, 7″, 7C, 6S, 6′′′, 2′′′′, and slender processes were randomly distributed over the echinate or baculate surface. In addition, we obtained rRNA sequences of F. setacea, gen. & sp. nov., but dinophytes that exhibit a partiform hypotheca did not show a close relationship to Gonyaulacales. Character evolution of thecate dinophytes may have progressed from the ancestral state of six postcingular plates, and two more or less symmetrically arranged antapical plates, towards patterns of only five postcingular plates (Peridiniales) or more asymmetrical configurations (Gonyaulacales). Based on our phylogenetic reconsiderations the contact between the posterior sulcal plate and the first postcingular plate, as well as the contact between an antapical plate and the distalmost postcingular plate, do not represent a rare, specialized gonyaulacoid plate configuration (i.e., the partiform hypotheca of cladopyxidoid dinophytes). Instead, these contacts correspond to the common and regular configuration of peridinioid (and other) dinophytes.

The dinoflagellate order Peridiniales encompasses several well circumscribed families. However, the family level of some genera, such as Bysmatrum and Vulcanodinium, has remained elusive for many years. Four Peridinium-like strains were established from the Atlantic coast of France and North Sulawesi, Indonesia through cyst germination or isolation of single cells. The cyst-theca relationship was established on specimens from the French Atlantic. Their morphologies were examined using light, scanning and transmission electron microscopy. The cells were characterized by a much larger epitheca relative to the hypotheca, a large anterior sulcal (Sa) plate deeply intruding the epitheca and a small first anterior intercalary plate. The plate formula was identified as Po, cp, X, 4 ', 3a, 7 '', 6C, 5S, 5 ''', 2 '''', shared by Apocalathium, Chimonodinium, Fusiperidinium and Scrippsiella of the family Thoracosphaeraceae but the configuration of Sa plate and anterior intercalary plates is different. Transmission electron microscopy showed that the eyespot was located within a chloroplast comprising two rows of lipid globules and thus belongs to type A. All four strains were classified within a new genus Caladoa as C. arcachonensis gen. et sp. nov. Small subunit ribosomal DNA (SSU rDNA), partial large subunit ribosomal DNA (LSU rDNA) and internal transcribed spacer ribosomal DNA (ITS rDNA) sequences were obtained from all strains. Genetic distance based on ITS rDNA sequences between French and Indonesian strains reached 0.17, suggesting cryptic speciation in C. arcachonensis. The maximum likelihood and Bayesian inference analysis based on concatenated data from SSU and LSU rDNA sequences revealed that Caladoa is monophyletic and closest to Bysmatrum. Our results supported that Caladoa and Bysmatrum are members of the order Peridiniales but their family level remains to be determined. Our results also support that Vulcanodinium is closest to the family Peridiniaceae.

We restudied the morphological complex comprising the cyst-based species Spiniferites elongatus/Spiniferites frigidus/Rottnestia amphicavata. We reviewed existing studies, and acquired new morphometric measurements of recent cysts from across the Northern Hemisphere, scanning electron microscopy (SEM) observations of cysts from Barents Sea surface sediments, and genetic analyses of cysts from the Beaufort Sea. The measurements suggest that populations and morphospecies cannot be distinguished based on morphometric criteria. Furthermore, sequential sediment trap samples from Hudson Bay reveal that morphological variation can occur at the same location over a few weeks, arguing against a uniform morphological response to environmental parameters. The SEM observations reveal a consistent gonyaulacacean tabulation (Po, 4′, 6′′, 6c, 5 s, *6′′′, 1p, 1′′′′). The small and large subunit ribosomal RNA genes and the internal transcribed spacer sequences obtained from differing cysts from the Beaufort Sea with morphologies attributable to the complex, including forms that correspond to Rottnestia amphicavata, were all identical and conform to those of Gonyaulax elongata from the Orkney Islands. The molecular analyses thus support the conclusion that the morphological variability is not reflected genetically and occurs within one species. Based on arguments against the generic attribution of amphicavata to Rottnestia, the continuum between the extreme ends of the morphological range, and the molecular data, we suggest Rottnestia amphicavata to be conspecific with Spiniferites frigidus, and both to be junior synonyms of Spiniferites elongatus. The morphometric data further indicate that Spiniferites ellipsoideus, an elongate cyst from the Miocene, can also be considered a junior synonym of Spiniferites elongatus. It is recommended to use two informal types in census work (i.e. Spiniferites elongatus – Beaufort morphotype for morphologies formerly assignable to Spiniferites frigidus/Rottnestia amphicavata, and Spiniferites elongatus – Norwegian morphotype for cysts with strongly reduced processes) to separate specimens at both extreme ends of the morphological spectrum from typical specimens of Spiniferites elongatus.

The thecal tabulation and body scale structure of the marine armoured dinoflagellate Heterocapsa, isolated from Philippines, were examined using LM, SEM and TEM, and its phylogenetic position was inferred from ITS and LSU rDNA sequences. Cells were ovoid and the plate tabulation (Po, cp, X, 5′, 3a, 7′′, 6c, 5s, 5′′′, 2′′′′) was consistent with most Heterocapsa species. The second anterior intercalary plate (2a) had a circular pattern with a thick marginal border free of pores. The nucleus was longitudinally elongated and curved, and located at the dorsal side of the cell. Discoid lobes of brownish chloroplast were peripherally distributed, and a pyrenoid was positioned at the centre. The triradiate body scales, measuring 250–300 nm in diameter, consisted of a roundish basal plate with six radiating ridges, nine peripheral uprights/spines, and three radiating spines. These components were identical to those of H. pseudotriquetra and H. steinii, except for the roundish outline of basal plate. Molecular phylogeny showed that the species clustered with H. pseudotriquetra and H. steinii. This species was differentiated from all other Heterocapsa species in the sausage-shaped nucleus and circular pattern on the 2a plate. This study proposed a novel species Heterocapsa philippinensis sp. nov. for the isolate.

During daily monitoring in Yongho Bay off Busan, Korea in 2019, an isolate of the dinoflagellate genus Heterocapsa was established in clonal culture. Light and electron microscopic examination revealed that the isolate was ellipsoid in shape, exhibiting a thecal plate arrangement (Po, cp, X, 5', 3a, 7″, 6c, 5s, 5‴, 2'''') consistent with most other Heterocapsa species. A large, elongated nucleus was positioned on the left side of the cell, a single reticulate chloroplast was located peripherally, and a single, starch-sheathed, spherical pyrenoid was present in the episome or near the cingulum. Morphologically, the isolate most closely resembles H. circularisquama and H. illdefina. Transmission electron microscopic examination of whole mounts revealed that the isolate had two body scale types, one of which was a complex, three-dimensional, fine structure distinct from other Heterocapsa species, whereas the other simpler type was structurally similar to the scales of H. horiguchii. Molecular phylogeny based on rRNA sequences revealed that the isolate was distantly related to morphologically similar species, but formed a sister lineage to H. horiguchii, a species characterized by a similar body scale morphology. Based on morphological, ultrastructural, and molecular data, we proposed it as a new species, Heterocapsa busanensis sp. nov.

Dinoflagellates are a major component of the modern plankton. Of the 2192 species of marine free-living dinoflagellates presently described, an increasing number are being shown to produce resting cysts (probably hypnozygotes) within their life cycle. With rare exception, only the resting cysts fossilize, so they are of central importance in tracing the history of dinoflagellates through geological time. Cysts of many of the more common dinoflagellate species have distinctive morphologies allowing their geographic and stratigraphic occurrences to be traced. An ever-increasing number of taxa are also being shown to produce distinctive and geologically preservable cysts, potentially enhancing our knowledge of the diverse representation of dinoflagellates through time. Here the organic-walled cysts of 73 rare, poorly known or morphologically problematic marine dinoflagellate cyst species belonging to the orders Gymnodiniales (nine species) and Peridiniales (64 species) are reviewed, described and illustrated, and their stratigraphic ranges assessed. The names Echinidinium aculeatum and Echinidinium transparantum are validated herein. © 2019 Elsevier B.V.

Minusculum (Lebour) Balech is one of four subgenera of the genus Protoperidinium Bergh 1881. Only five species of this subgenus have been discovered worldwide, most of which are distributed in cold waters. In this study, Protoperidinium anomaloplaxum (Balech) Balech is reported from Vietnam and thus for the first time from Asia-Pacific waters. This species is illustrated with line drawing, light and scanning electron microscopic photographs and described details of the ornamentation of the thecal plates as well as its geographic distribution.

20 pages, 10 figures, 1 table, supporting information https://doi.org/10.1111/jpy.12984, Marine benthic dinoflagellates are interesting not only because some epiphytic genera can cause harmful algal blooms but also for understanding dinoflagellate evolution and diversification. Our understanding of their biodiversity is far from complete, and many thecate genera have unusual tabulation patterns that are difficult to relate to the diverse known phytoplankton taxa. A new sand-dwelling genus, Pachena gen. nov., is described based on morphological and DNA sequence data. Three species were discovered in distant locations and are circumscribed, namely, P. leibnizii sp. nov. from Canada, P. abriliae sp. nov. from Spain, and P. meriddae sp. nov. from Italy. All species are tiny (about 9–23 μm long) and heterotrophic. Species are characterized by their tabulation (APC 4′ 3a 6′′ 5c 5s 5′′′ 2′′′′), an apical hook covering the apical pore, an ascending cingulum, and a sulcus with central list. The first anterior intercalary plate is uniquely “sandwiched” between two plates. The species share these features and differ in the relative sizes and arrangements of their plates, especially on the epitheca. The ornamentation of thecal plates is species-specific. The new molecular phylogenies based on SSU and LSU rDNA sequences contribute to understanding the evolution of the planktonic relatives of Pachena, the Thoracosphaeraceae, This work was supported by a postdoctoral research salary to MH and AY from the Assembling the Tree of Life grant (NSF #EF‐0629624) and operating funds to BSL from the National Science and Engineering Research Council of Canada (NSERC 2019‐03986); AR thanks R. Gallisai (ICM‐CSIC) and T. Slámová (Univ. Prague, Czech Republic) for their help during samplings and samples processing. AR was funded by a MECD grant “Estancia de Movilidad en el extranjero José Castillejo” (CAS17/00237), a “Senckenberg Taxonomy Grant 2017″, and a DAAD “Research Stays for University Academics and Scientists 2018” Grant (91644317). CTS thanks Prof. Antonella Lugliè for the continuous and important economic and scientific support. CTS was funded by a DAAD Grant within the “Research Stays for University Academics and Scientists 2014” Grant (A/14/01530), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

The taxonomy of the dinoflagellate cyst-based genus Votadinium has been in need of revision. This was accomplished here by integrating morphology, LSU rDNA sequences, and cyst wall composition analyses through micro-Fourier transform infrared spectroscopy. Three new species, Votadinium pontifossatum, V. rhomboideum and V. reidii, were described as cyst stages of Protoperidinium paraoblongum, P. quadrioblongum, and P. steidingerae, respectively. A previously undescribed type of ornamentation was reported for V. pontifossatum. A fourth new species was assigned to V. concavum. Furthermore, Lejeunecysta psilodora Benedek (=Lejeunecysta psuchra Matsuoka), was re-described as V. psilodora and the holotype re-illustrated, as was done for the holotype of V. spinosum Reid. New illustrations were provided for V. elongatum and V. nanhaiense. LSU rDNA sequences of V. concavum revealed its placement in the Oceanica section of the genus Protoperidinium, supporting earlier evidence that the Oceanica section and the cyst based genus Votadinium form a monophyletic clade. Thus, Votadinium could be considered the cyst equivalent of the motile-defined Oceanica section. The cyst walls of Votadinium spinosum, V. calvum and V. pontifossatum are built from carbohydrate-based macromolecules with N-containing functional groups in agreement with the heterotrophic nature of their motile stage. Comparison with related genera Trinovantedinium and Quinquecuspis reveals that the species and genera can be separated based on cyst wall composition, supporting the phylogeny based on molecular data and/or ecological differences. Furthermore, Trinovantedinium applanatum spectra unexpectedly show an additional absorption at 1510 cm−1 indicating an aromatic group that is commonly reported for sporopollenin and not seen in dinoflagellate cysts so far. This study stabilizes the taxonomy of the cyst genus Votadinium, clarifies its relationship to the Oceanica section of Protoperidinium, and further supports the application of whole cyst wall chemistry in helping address problems in dinoflagellate cyst taxonomy and ecology.

Unicellular dinophytes include a considerable number of harmful algae and potent producers of toxins. The dinophyte fossil record is one of the richest among protists and indicates a geologically old origin of the group dating back to the Triassic. Besides of these records, very few molecular dating studies of dinophytes have been published to date, precluding an understanding of the diversification history of these organisms. In the present study, we used first appearances in the fossil record for the best-represented dinophyte lineages, namely Gonyaulacales and Peridiniales, to calibrate a molecular phylogeny. It is inferred from ribosomal RNA sequence data covering a representative taxon sampling of all currently recognised lineages. Dinophytes may have started diversifying during main tectonic events of the supercontinent Pangaea, witnessing and surviving some of the biggest mass extinction events on Earth. Groups including harmful dinophytes originated at different points in time, but they all predate the Cretaceous–Paleogene boundary. Our chronogram provides a first time frame and may stimulate studies in future bringing molecular phylogenetics of dinophytes and their impressive fossil record together in more detail.

Dinoflagellates are an extremely diverse group of unicellular eukaryotes that represent an important part of marine plankton communities. Among other secondary metabolites, these microorganisms are known to produce toxins such as the saxitoxins, karlotoxins, amphidinolides, okadaic acid or brevetoxins, which are extremely toxic for marine fauna and ultimately humans who consume contaminated seafood. The extreme biodiversity of dinoflagellates undoubtedly mirrors an inexhaustible reservoir of compounds, yet the chemodiversity of dinoflagellates is still poorly studied, due in part to constraints linked to the difficulty of isolating and cultivating these organisms. Nevertheless, an increasing number of new dinoflagellate secondary metabolites have been described in recent years. Here, we review these new advances in the isolation and characterization of bioactive metabolites from several dinoflagellates (Gymnodiniales, Amphidinium, Karlodinium, Karenia), Peridiniales (Vulcanodinium), Gonyaulacales (Alexandrium, Gambierdiscus, Ostreopsis), Prorocentrales (Prorocentrum) and Dinophysiales (Dinophysis).

Organic-walled resting cysts of planktonic dinoflagellates occur commonly in modern marine sediment where they represent, with rare exceptions, the only geologically preservable part of the life cycle. Although many species do not produce fossilizable resting cysts, upper Quaternary sediments contain a diverse cyst record that is used frequently for paleoenvironmental reconstruction and stratigraphic analysis. Reconstructions of past sea-surface conditions rely on an understanding of the distributions of dinoflagellate cysts in modern sediments linked to their respective environmental parameters, underpinned by sound taxonomy and standardized nomenclature. Stratigraphic studies additionally require knowledge of morphological details to distinguish extant from similar extinct taxa. Here, 51 dinoflagellate cyst species and two informal cyst morphotypes that are commonly encountered during routine palynological analysis of upper Quaternary marine sediments from the Northern Hemisphere are briefly described taxonomically and illustrated. In addition, their lowest stratigraphic occurrences are provided.

A small armed dinoflagellate bloomed in the aquaculture ponds off the coast of Liaodong Bay, Bohai Sea of China, resulting in heavy mortalities of the cultured prawns (Penaeus japonicus) and larvae of Chinese mitten handed crabs (Eriocheir sinensis). The bloom-forming species was successfully isolated, and cellular morphology of the specimen was consequently investigated through light, fluorescent and electron microscopy. The small ((14.4±1.6) μm in length) ellipsoid cells show typical Heterocapsa thecal plate arrangement (Po, cp, 5′, 3a, 7′′, 6c, 5s, 5′′′, 2′′′′). The episome is evidently bigger than the hyposome. One to three spherical pyrenoids are located above or beside the large elongated nucleus. The body scale is characterized by a triangle basal plate with one central upright and nine peripheral spines. Above all, Heterocapsa bohaiensis could be distinguished from other Heterocapsa species by the combination of the cell size, morphology, cellular structure and body scale. Sequence analyses of both ITS and LSU regions reveal the significant genetic divergence between H. bohaiensis and other established species in this genus, further supporting novelty of this species. Noticeably, different sample treatment methods resulted in morphological variation of the apical pore complex (APC) of H. bohaiensis, which needs to be taken into account in future study.

A research probing for the unrecorded and taxonomically undescribed indigenous species has been initiated since 2006. Samples were collected from an intertidal zone along the coasts of Korea as well as around the Jeju Island. We have found five unrecorded species of four genera belonging to the order Dinophysiales, Gymnodiniales, Peridiniales, and Prorocentrales. The species are as follows, Sinophysis canaliculata (2017) Bispinodinium angelaceum (2015), Cabra armorica (2016), Prorocentrum bimaculatum (2017), and P. tsawwassenense (2017) (note; The numbers in parenthesis refer to the year in which the species was reported as unrecorded indigenous species by National Institute of Biological Resources, NIBR hereafter).

Because of a great variety of remote localities and cold habitats, the Tatra Mountains are home to many freshwater protist lineages. Dinophytes have been subjected to a number of studies from this area dating mostly to the first half of the 20th century, but their true diversity remains elusive until today. We collected water tow samples at five lakes in the Tatra Mountains in order to establish monoclonal strains. We found four lineages that were distinctive in terms of morphology and DNA sequence data and that could be assigned to peridinialean Parvodinium. These four species can be readily distinguished based on a general shape, size, thecal plate tabulation pattern and presence or absence of an antapical protuberance. The plate overlap pattern is considered conserved at higher taxonomic levels, and the divergent keystone Plate 3' in Parvodinium marciniakii, sp. nov., thus appears as a striking diagnostic character. For taxonomic conclusion, we describe two species new to science and validate three old scientific names (i.e., one species and two varieties). Our study underlines that the biodiversity assessment, particularly of species adapted to cold environments, is anything but completed as shown from remote and unexplored European landscapes such as the Tatra Mountains.