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Protoperidinium claudicans is a planktonic, heterotrophic, bioluminescent dinoflagellate species commonly found in neritic waters. It has long been considered to display phenotypic variation in its second anterior intercalary plate, which could vary between quadra, penta and hexa. The equivalent spinose, cordate cyst goes under the name of Votadinium spinosum. Here we perform incubation experiments with cysts from France, Canada, China and Japan, which demonstrate that P. claudicans forms a species complex, with at least two ribotypes with a penta configuration (P. claudicans) and one with a quadra configuration (P. carriae sp. nov.). A fossil-based cyst, V. multispinosum sp. nov., is described as the equivalent of P. carriae. Molecular phylogenetics using large subunit ribosomal DNA supports these observations. The cyst–theca relationships for Votadinium psilodora and another, undescribed, cordate, spineless Votadinium species are also reported from China. Macromolecular analyses of the cyst wall of V. multispinosum reveal it is comprised of a protein-rich carbohydrate compound. We show that this compound is not uncommon in dinoflagellate and ciliate cysts and that it is unlikely to preserve very well upon sedimentation and burial. [ABSTRACT FROM AUTHOR]

It is notable that in a close relative, I Fensomea setacea i , which also carries setae, scanning electron microscope (SEM) micrographs do not show the setae even though they are visible in the light microscope images, confirming that there is a change due to the preparations for SEM: there are some I Fensomea i cells shown without setae, and others with setae (Gottschling et al. [6], fig. 2). Gottschling et al. ([7]) remarked that in our attempt to epitypify the dinoflagellate I Micracanthodium setiferum i (Lohmann) Deflandre we did not report images of the setae, and that we 'did not show or mention the characteristic number and arrangement of the setae'. [Extracted from the article]

The cyst-defined extant Spiniferites elongatus Reid 1974 and Spiniferites membranaceus (Rossignol 1964) Sarjeant 1970 are environmentally significant fossil-species of the Quaternary, the former often dominating polar and subpolar assemblages. Following cyst incubation experiments and the establishment of cultures, these species were emended to incorporate information on their motile stages, and transferred to the non-fossil genus Gonyaulax Diesing 1866, as Gonyaulax elongata (Reid 1974) Ellegaard et al. 2003 and Gonyaulax membranacea (Rossignol 1964) Ellegaard et al. 2003. This unified approach to dinoflagellate nomenclature severs an important link with the fossil-genus Spiniferites Mantell 1850. We have applied dual nomenclature, as sanctioned by the International Code of Nomenclature for algae, fungi and plants, in returning these species to their previous assignments as Spiniferites elongatus and Spiniferites membranaceus, and we propose Gonyaulax ovum (Gaarder 1954) comb. nov., emend. and Gonyaulax lewisiae sp. nov., respectively, as their equivalent non-fossil species. A distinctive morphotype initially described as Rottnestia amphicavata var. amphicavata Dobell & Norris in Harland et al. 1980 is proposed as Spiniferites elongatus forma amphicavata stat. nov. [ABSTRACT FROM AUTHOR]

Dual nomenclature in dinoflagellates is supported under the current nomenclatural code for algae, fungi and plants and allows a fossil-defined (usually cyst) species to bear a name other than that of its equivalent non-fossil species, as established for example by incubation experiments. Two names can then apply to the same cyst morphotype, reflecting the separate but overlapping concepts and criteria used for fossil- and non-fossil taxa. Fossil-species are normally and logically assigned to fossil-genera and non-fossil species to non-fossil genera, a practice that facilitates dual nomenclature. Inconsistencies and ambiguities arise when binomials combine the names of fossil- with non-fossil taxa. Examples of this hybridised nomenclature and its consequences are examined, with problems identified and potential solutions discussed. Accordingly, a new non-fossil genus Lingulaulax is proposed with Lingulaulax polyedra (von Stein 1883) comb. nov. as its type and equivalent to the fossil-species Lingulodinium machaerophorum (Deflandre & Cookson 1955) Wall 1967, along with the new combination Lingulaulax milneri (Murray & Whitting 1899); the genus Lingulodinium Wall 1967 is retained in its exclusively fossil status. The non-fossil name Gonyaulax ellegaardiae Mertens et al. 2015 is validly published herein. [ABSTRACT FROM AUTHOR]

Dinoflagellate species are traditionally defined using morphological characters, but molecular evidence accumulated over the past several decades indicates many morphologically-based descriptions are inaccurate. This recognition led to an increasing reliance on DNA sequence data, particularly rDNA gene segments, in defining species. The validity of this approach assumes the divergence in rDNA or other selected genes parallels speciation events. Another concern is whether single gene rDNA phylogenies by themselves are adequate for delineating species or if multigene phylogenies are required instead. Currently, few studies have directly assessed the relative utility of multigene versus rDNA-based phylogenies for distinguishing species. To address this, the current study examined D1-D3 and ITS/5.8S rDNA gene regions, a multi-gene phylogeny, and morphological characters in Gambierdiscus and other related dinoflagellate genera to determine if they produce congruent phylogenies and identify the same species. Data for the analyses were obtained from previous sequencing efforts and publicly available dinoflagellate transcriptomic libraries as well from the additional nine well-characterized Gambierdiscus species transcriptomic libraries generated in this study. The D1-D3 and ITS/5.8S phylogenies successfully identified the described Gambierdiscus and Alexandrium species. Additionally, the data showed that the D1-D3 and multigene phylogenies were equally capable of identifying the same species. The multigene phylogenies, however, showed different relationships among species and are likely to prove more accurate at determining phylogenetic relationships above the species level. These data indicated that D1-D3 and ITS/5.8S rDNA region phylogenies are generally successful for identifying species of Gambierdiscus, and likely those of other dinoflagellates. To assess how broadly general this finding is likely to be, rDNA molecular phylogenies from over 473 manuscripts representing 232 genera and 863 described species of dinoflagellates were reviewed. Results showed the D1-D3 rDNA and ITS phylogenies in combination are capable of identifying 97% of dinoflagellate species including all the species belonging to the genera Alexandrium, Ostreopsis and Gambierdiscus, although it should be noted that multi-gene phylogenies are preferred for inferring relationships among these species. A protocol is presented for determining when D1-D3, confirmed by ITS/5.8S rDNA sequence data, would take precedence over morphological features when describing new dinoflagellate species. This protocol addresses situations such as: a) when a new species is both morphologically and molecularly distinct from other known species; b) when a new species and closely related species are morphologically indistinguishable, but genetically distinct; and c) how to handle potentially cryptic species and cases where morphotypes are clearly distinct but have the same rDNA sequence. The protocol also addresses other molecular, morphological, and genetic approaches required to resolve species boundaries in the small minority of species where the D1-D3/ITS region phylogenies fail. [ABSTRACT FROM AUTHOR]

Among dinoflagellates, extant cladopyxidaceans may provide a missing link to better understand the first evolutionary transformations from ancestral configurations toward the more abundant and more derived patterns in Gonyaulacales and Peridiniales. A restudy of the extant, motile-defined Micracanthodinium setiferum using plankton samples from the Indian and Atlantic oceans and the Mediterranean Sea demonstrates that the correct plate formula is Po, Pt, X, 3′ + *4′, 4a, 7′′, 7C, 4S, ?6′′′, 0p, 2′′′′. A ventral pore is found between 1′, 3′ and *4′. A restudy of the extinct, fossil-defined Cladopyxidium saeptum from the upper Paleocene of Delaware (USA), demonstrated the presence of an identical tabulation. A ventral pore (= porichnion) was positioned between *1′ and 7′′. Cladopyxidium is morphologically closer to Micracanthodinium than to Cladopyxis. Since Cladopyxidium has been extinct since the middle Eocene, it is unlikely that Micracanthodinium and Cladopyxidium have a direct biological link; the close morphological similarity between them does, however, suggest an important phylogenetic relationship between them in the evolution of cladopyxidaceans. [ABSTRACT FROM AUTHOR]

Micracanthodinium setiferum is a very distinctive but poorly known dinophyte with characteristically delicate, unbranched, filiform and pointed setae. A recent study by Mertens et al. (2022, Palynology 46: 1934908) aims to clarify the taxonomy of the species and to introduce two new formae acknowledging the presence or absence of setae in environmentally collected cells. We assert that the epitype choice of illustrations by these authors is inappropriate, but also not achieved following the rules of the International Code of Nomenclature for algae, fungi, and plants (ICN). Additionally, the two new formae are not described in accordance with the rules of the ICN. A more suitable epitype may therefore be chosen, once corresponding physical material from the type locality off Sicily is at hand. The taxonomic identity of M. setiferum meanwhile remains elusive. [ABSTRACT FROM AUTHOR]

A new dinoflagellate cyst genus and species are described here as Hiddenocysta gen. nov. and Hiddenocysta matsuokae sp. nov. from Holocene sediments in a core from the west coast of Vancouver Island (British Columbia, Canada). The genus Hiddenocysta encompasses spherical to ovoid skolochorate cysts, characterized by a gonyaulacoid plate pattern and a 2P precingular archeopyle. The species H. matsuokae is characterized by a granular wall and slender trifurcate processes with heavily perforated process bases. Two end members are described here based on process morphology and number of processes (formas 1 and 2). Cyst wall chemistry is analyzed using micro-Fourier transform infrared (FTIR) spectroscopy and reveals a unique dinosporin composition consistent with a gonyaulacoid autotrophic feeding strategy. [ABSTRACT FROM AUTHOR]

The taxonomy of the dinoflagellate cyst-based genus Votadinium has been in need of revision. This is accomplished here by integrating morphology, large subunit (LSU) rDNA sequences, and cyst wall composition analyses through micro-Fourier transform infrared spectroscopy. Three new species, Votadinium pontifossatum, V. rhomboideum and V. reidii, are described as cyst stages of Protoperidinium paraoblongum, P. quadrioblongum, and P. steidingerae, respectively. A previously undescribed type of ornamentation is reported for V. pontifossatum. A fourth new species is assigned to V. concavum. Furthermore, Lejeunecysta psilodora Benedek (= Lejeunecysta psuchra Matsuoka), is re-described as V. psilodora and the holotype re-illustrated, as is done for the holotype of V. spinosum Reid. New illustrations are provided for V. elongatum and V. nanhaiense. LSU rDNA sequences of V. concavum reveal 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 a 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. [ABSTRACT FROM AUTHOR]

New Zealand benthic and epiphytic dinoflagellate records increased in recent years as harmful algal bloom research increased. This was largely due to risk assessments of micro-algal biotoxins for the seafood industry and concerns regarding ciguatera fish poisoning in humans from toxic finfish. High-throughput sequencing enabled the detection of dinoflagellate species that were previously overlooked by microscopy, particularly where diatoms or sediments obscured visual identification. This checklist includes new species records for New Zealand and species usually considered planktonic, but which have benthic life stages. Thirty-one dinoflagellate genera were recorded from isolations and descriptions of living cells: Alexandrium, Amphidinium, Archaeperidinium, Azadinium, Biecheleria, Blastodinium, Bysmatrum, Coolia, Crypthecodinium, Cryptoperidiniopsis, Durinskia, Ensiculifera, Fukuyoa, Gambierdiscus, Gymnodinium, Gyrodinium, Heterocapsa, Karenia, Kryptoperidinium, Ostreopsis, Pelagodinium, Pentapharsodinium, Pfiesteria, Polarella, Prorocentrum, Protodinium, Protoperidinium, Pseudopfiesteria, Scrippsiella, Togula and Vulcanodinium. A further nine genera were detected by high-throughput sequencing: Cachonina, Dinophysis, Fragilidium, Gonyaulax, Karlodinium, Lepidodinium, Protodinium, Symbiodinium and Woloszynskia. [ABSTRACT FROM AUTHOR]

The first chapter of this special issue introduces the proceedings of two workshops concerning the cyst-based genus Spiniferites Mantell 1850. The historical background of the cyst-based genus Spiniferites, its closely related genera and the theca-based genus Gonyaulax Diesing 1866 is presented here. [ABSTRACT FROM AUTHOR]

Cabra is a genus of marine thecate sand-dwelling dinoflagellates that is poorly known and of which only two species are described, C. matta and C. reticulata. In one fixed sample collected in 2007 in South Brittany, both of these species were recorded, together with a new third one. Cells of the three taxa were isolated and their morphology was characterized using scanning electron microscopy. New features previously unseen in C. matta were observed including the presence of a dense group of pores on the first antapical plate and the existence of pores of two different size classes on thecal plates. Cabra aremorica sp. nov. is 37–40 µm long and 31–38 µm deep and possesses a thecal pattern very similar to the other species described in the genus. However, C. aremorica differs from them by its overall ornamentation consisting in shallow alveolae, its polyhedral shape, and its very atypical apical pore complex. Observations of the third cingular plate c3 on the three Cabra species revealed the presence of a narrow extension that lays vertically and borders the ‘x’ (5″) plate on the ventral side of cells, which appears to be a constant feature in the genus. This fact not previously reported is crucial for the interpretation of the plate pattern and is very peculiar among dinoflagellates. [ABSTRACT FROM AUTHOR]

A new sand-dwelling dinoflagellate species, Cabra reticulata sp. nov., is described from sandy habitats in the south of Brittany (northwestern France). This new species possesses the characteristics of the 'unusual' genus, Cabra Murray et Patterson. The thecal plate formula is Po Pt 3' 1a 4'' 'x' 3c ?s 5''' 1'''' (or alternatively interpreted as Po Pt 4' 0a 4'' 'x' 3c ?s 5''' 1''''). Because of the strong lateral compression, cells of C. reticulata are frequently seen laterally and have a polygonal shape, with three prominent antapical pointed flanges and a dorsal spine in the anterior part of the hypotheca. The cingulum is ascending and incomplete. The thecal surface is ornamented with strong reticulations forming polygonal areolae, which differs from C. matta Murray et Patterson, the type species of the genus. In addition to their different size and shape, a detailed study of C. reticulata by scanning electron microscopy also revealed several different plate features. Plates of the cingulum, c1 and c3, have no reticulations and are ornamented with shallow round areolae, while c2 is only faintly reticulated. Plate 1'''' is also characteristic because dorsally it forms a prominent pointed flange and ventrally bears a peculiar small area of densely arranged pores or tiny areolae. A similar finding has previously been described in Roscoffia capitata Balech. In the description of the genus, it was suggested that Cabra is closely related to species of the genus Roscoffia, and our observations strengthen this hypothesis. Prior to this study, C. reticulata was probably observed in the Virgin Islands, Caribbean Sea, but was tentatively identified as Thecadinium sp. and not fully described. Thus, C. reticulata appears to be present on both sides of the Atlantic Ocean and to occupy benthic habitats in temperate and tropical areas. [ABSTRACT FROM AUTHOR]

A new heterotrophic armoured dinoflagellate is described from sand habitats in eastern Australia. Cabra matta gen. nov., sp. nov., lacks plastids and an eyespot. The thecal plate formula is Po 4′ 4" 'x' 3c ?s 5′′' 1′′". Its plate pattern differs from all currently described dinoflagellate genera, but is most similar to the genus Roscoffia . Cabra matta shows some similarity to species currently placed in the family Podolampaceae, however its evolutionary affinities and hence its position within the dinoflagellate systematic hierarchy remain unresolved. [ABSTRACT FROM AUTHOR]