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Tubastraea, commonly known as sun coral, is a genus of brightly coloured azooxanthellate corals in the family Dendrophylliidae. The diversity of this genus is low, with only seven recognized species. Herein, we describe Tubastraea megacorallita sp. nov. from Hong Kong based on morphological and molecular analyses. This new species exhibits several characteristics of the genus including being colonial, having a rough texture of corallum and no epitheca. It can be distinguished from its congenerics by bigger corallites, and the Pourtalès plan arrangement of its septa. The rDNA gene sequences (consisting of ITS1, 5.8S, ITS2, 18S and 28S) showed 2.45–5.18% divergence from those of its closest relatives, T. coccinea and T. micranthus.

Axophyllum cavum Trautschold, 1879 (Rugosa: Stauriida: Axophyllidae), a common solitary coral in the Moscovian stage of the Moscow Basin, is briefly redescribed. It is characterized by the small size of adult individuals (a few centimeters) and a high occurrence frequency of rootlet structures on the epitheca that supported the attachment of the coral on the substrate. The extensive collection of small-sized A. cavum (up to 2 cm) with various rhizoid structures and attachment scars from the Staryi Yam locality (Moscow area, Pakhra River, abandoned Yamskoi Quarry) was studied. The morphogenesis of rhizoids was is described in detail.

Heterocorals represent an enigmatic group of Palaeozoic corals, known from relatively short time intervals in the Devonian and Carboniferous periods. The major differences between Heterocorallia and other Palaeozoic corals are the lack of an external theca (epitheca), lack of calices and the presence of dichotomously dividing septa-like structures. Heterocoral skeleton was presumably externally covered by the soft tissue and each branch of their skeleton has, until now, been regarded as a corallite–a skeleton of a single polyp. We investigated upper Famennian Oligophylloides from Morocco, focussing on branching processes, wall structure, previously poorly known initial growth stages and the growing tip, described here for the first time. We demonstrate that Oligophylloides shows a unique colony development not known in any group of anthozoans possessing a septate-like architecture and suggest that the previously postulated homology between true septa in hexa- and rugose corals on one hand, and Oligophylloides on the other, must be rejected. Based on the skeleton structure and branching patterns, we postulate, contrary to former ideas, that the stem and branches of heterocorals represent the skeleton of a multi-polyp colonial coral, similar to many extant octocorals. We found numerous potential homologies with octocoral skeletons (notably the Keratoisidinae within the Isididae) and, as a result, we propose the inclusion of the order Heterocorallia within the subclass Octocorallia. This suggestion requires, however, further research on the other taxa of heterocorals. We also propose some changes to the morphological terminology for the Heterocorallia.

A phototrophic dinoflagellate belonging to the genus Scrippsiella was isolated from a water sample collected from Masan Bay, Korea. Using a clonal culture of this dinoflagellate, its morphology was analysed with light, scanning and transmission electron microscopy and small subunit (SSU), large subunit (LSU), and internal transcribed spacer ribosomal DNA (ITS rDNA) sequences were studied. The dinoflagellate plate formula was Po, x, 4ʹ, 3a, 7″, 6c (5c + t), 5s, 5ʹ″, and 2″″, consistent with Scrippsiella. The dinoflagellate had a rounded epitheca, unlike most Scrippsiella species, which have a conical epitheca. Furthermore, it had a narrow, symmetrical, and pentagonal 1ʹ plate, unlike other Scrippsiella species. In addition, it had three intercalary plates of different sizes. This species had noncalcareous cysts, unlike most Scrippsiella species, which have calcareous cysts. The LSU rDNA sequence of the dinoflagellate was about 2% different from Scrippsiella enormis, the closest Scrippsiella species...

A new species of marine sand-dwelling dinoflagellate, Plagiodinium ballux N. Yamada, Dawut, R. Terada & T. Horiguchi is described from a deep (36 m) seafloor off Takeshima Island, Kagoshima Prefecture, Japan in the subtropical region of the northwest Pacific. The species is thecate and superficially resembles species of Prorocentrum, but possesses an extremely small epitheca. The cell varies from ovoid to a rounded square, and is small (15.0-22.5 mu m in length) and laterally compressed. The thecal plates are smooth and the thecal plate arrangement (Po, 1 ', 0a, 5 '', 5C, 2S, 5"', 0p, 1 '''') is similar to that of Plagiodinium belizeanum, the type species of the genus. Molecular phylogenetic analyses based on SSU rDNA and partial LSU rDNA reveal that the dinoflagellate is closely related to P. belizeanum, but it can be clearly distinguished by its size and cell shape. This suite of morphological and molecular differences leads to the conclusion that this deep benthic dinoflagellate represents a new species of the genus Plagiodinium.

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)

A new species of the dinoflagellate genus Bysmatrum was isolated from tidal pool samples originating from Cape Peninsula, South Africa. This new species was investigated by light, scanning and transmission electron microscopy, and its phylogenetic affinities were analyzed using molecular data. Cells were pentagonal in ventral view, 25–45 μm long and 20–42.5 μm wide and only slightly flattened in a dorsiventral plane. The epitheca, in apical view, was almost circular, with a slight ventral depression. Plate tabulation (PO, X, 4′, 3a, 7″, 6c, 4s, 5′′′, 2′′′′) was typical for the genus Bysmatrum. Apical plate 1′ was heptagonal and broadly asymmetric, with an elongated, fingerlike extension at the base. The intercalary plates 2a and 3a were separated by a direct connection between plates 3′ and 4″. The thecal plates were perforated by pores of different sizes and ornamented with linearly arranged reticulations. Intercalary bands were smooth, and antapical plates were not indented. This new species d...

Protoperidinium is one of the most important genera of armoured marine dinoflagellates. Despite its importance and many previous studies on this genus, the descriptions of many species are incomplete, their diagnostic features not properly described and illustrated and most species have been illustrated, if at all, only by line drawings and not documented by micro-photography. As here described, examinations of about 600 phytoplankton net samples collected from Viet Nam and adjacent coastal waters over the last decade revealed about 100 species of Protoperidinium, ten of which belong to the section Oceanica and this paper is the first in a series describing all species of Protoperidinium found in Vietnamese waters. The Oceanica species are described and illustrated by light, and for some also by scanning electron, microscopy. The species are: Protoperidinium claudicans, P. depressum, P. depressum var. claudicanoides, P. larsenii sp. nov., P. murrayi, P. oceanicum f. bisintercalares comb. nov., P. oceanicum var. tenellum comb. nov., P. paraoblongum, P. venustum and P. venustum var. facetum. Protoperidinium larsenii L. Phan Tan, L. Nguyen-Ngoc, and H. Doan-Nhu is new to science. It was found in the coastal waters of Rach Gia in Kien Giang Province, western part of south Viet Nam (Gulf of Thailand). The new species is characterized by its broad shape, conical epitheca and short, non-divergent antapical horns; the 1’ plate is asymmetrical, there are 3 anterior intercalary plates, the 2a plate is quadrangular; and the sutures connecting the 6” plate with the 4’ plate and the 7” form an almost straight line. By these features P. larsenii differs from the similar species P. claudicans and P. latidorsale. Protoperidinium oceanicum (Vanh ffen) Balech () f. bisintercalares (Graham) H. Doan-Nhu, L. Phan-Tan, L. Nguyen-Ngoc, and J. Larsen comb. nov. and Protoperidinium oceanicum (Vanh ffen) Balech () var. tenellum (Graham) L. Nguyen-Ngoc, L. Phan-Tan, H. Doan-Nhu and J. Larsen comb. nov. are two new combinations.

The poorly known dinoflagellate Sinophysis canaliculata, which was originally described from the Indian Ocean, was abundant in a collection from 2015 from Rapa Iti, a small, remote island of French Polynesia. Since the taxonomic description of this species was incomplete, a detailed morphological study was carried out. The theca was studied with epifluorescence microscopy using Solophenyl Flavine 7GFE500, a fluorescent dye specific to cellulose. This fluorophore was used successfully for the first time with a thecate dinoflagellate. It has the advantage of using blue excitation light and avoids the fading of fluorescence encountered with other dyes with long excitation time. Using this technique and high-resolution field emission scanning electron microscopy, the thecal plate pattern was clarified, and the epitheca had six major plates, 4E and 2A. A conspicuous apical pore was present on the left side of the epitheca. A smaller pore was located on the ventral left side of the apical pore. The ap...

The genus Alexandrium comprises some of the most potentially toxic marine algae. A new toxic species of Alexandrium, A. fragae sp. nov., was found in Guanabara Bay, Rio de Janeiro, southern Brazil. The new species produces GTX2&3 and STX. The cell morphology of A. fragae resembles A. minutum in many characters, including the small size; the rounded-elliptical shape; and the shapes of the apical pore complex (APC), first apical plate (1'), sixth precingular plate (6″), and anterior and posterior sulcal plates (s.a. and s.p.). The main diagnostic characters of A. fragae are the ornamentation pattern, smooth epitheca and reticulated hypotheca, all of which were present in both natural populations and cultures. Phylogenies inferred from the ITS, LSU, and SSU rDNA of A. fragae showed that A. fragae clustered in a well-supported clade, distinct from other Alexandrium species. Morphology and molecular analyses based on ITS and LSU rDNA indicated that A. fragae strains and Alexandrium sp. from Japan (D163C5, D164C6) are a single species. Our findings suggest that the Alexandrium morphotype with a smooth epitheca and reticulated hypotheca, previously identified as A. minutum in different geographic regions, may corresponds to A. fragae.

11 pages, 8 figures, 1 table, supplementary data https://doi.org/10.1016/j.hal.2019.04.001, The heterotrophic sand-dwelling dinoflagellate Thecadinium inclinatum has been re-examined by light and scanning electron microscopy in order to resolve the discrepancies on its plate pattern from the literature, and to obtain its phylogenetic information single-cell PCR technique has been used. The comparison of morphological and molecular information available for other Thecadinium species confirms the genus is polyphyletic and T. inclinatum seems not related to other representatives of the genus sensu lato. Thus, a new genus and combination for the species, Psammodinium inclinatum gen. nov., comb. nov. is proposed. Cells are heterotrophic and strongly laterally flattened, with sulcal pocket. The revised tabulation is: APC 3' 7” 7c 7s? 5”' 1p 2”” with a long-shank fishhook-shaped apical pore and descending cingulum. The cingulum inclines ventrally and declines on the right lateral side producing an asymmetrical epitheca. The epitheca is much smaller than the hypotheca. The phylogenetic results showed a strong relationship with the autotrophic epiphytic genera Gambierdiscus and Fukuyoa, being closely related with the latter. The Gambierdiscus species typically have a tropical and sub-tropical distribution and produce ciguatoxins, causing thousands of intoxications every year by consumption of contaminated fish. Fukuyoa representatives have a wider distribution including warm and temperate waters, and it has been demonstrated that they are also able to produce ciguatoxins, even though at lower amounts. P. inclinatum, which potential toxicity remains to be determined, represents an interesting independent evolutionary branch that resulted in the loss of chloroplasts, the strong lateral compression and the adaptation to sandy habitats in temperate and cold waters, A.R. was funded by a “Senckenberg Taxonomy Grant, 2017”, and a DAAD “Research Stays for University Academics and Scientists, 2018, Grant 91644317”

Symbiotic algae of primary polyps play an important role in calcification of coral skeletons. However, the function of the symbiotic algae, including the way they influence the physical features of their host skeleton under various conditions, is not well understood. We used X-ray micro-computed tomography to observe skeletal shape characteristics in symbiotic and aposymbiotic primary polyps of Acropora digitifera that were cultured at various temperature and pCO2 levels (temperature 27, 29, 33 °C; pCO2 400, 800, 1000 µatm). Symbiotic polyps had a basal plate with a well-developed folding margin supporting the branched skeleton, whereas aposymbiotic ones did not. The features of the folding margin suggest that it might be the initial growth stage of the epitheca. In addition, three-dimensional (3-D) morphological measurements made by X-ray micro-computed tomography show that the branched skeletons of symbiotic primary polyps were taller than those of aposymbiotic ones, suggesting that zooxanthellae in coral primary polyps play a critical role in the height growth of skeletal branches. Furthermore, results of the temperature- and pCO2-controlled experiments suggest that global warming might greatly affect the activity of zooxanthellae, whereas ocean acidification might reduce calcification by damaging the coral host itself. Our findings provide new knowledge about the role of zooxanthellae in coral calcification. This article is protected by copyright. All rights reserved.

The benthic dinoflagellate genus Sinophysis is known from tropical and temperate areas with seven species described. To date, none of them has been fully characterized, and the epithecal plate pattern remains unclear at the genus level. A taxonomic investigation from Martinique Island facilitated the characterization of six species: Sinophysis microcephala, Sinophysis ebriola, Sinophysis stenosoma, Sinophysis cf. verruculosa and two new species. They were studied and illustrated by light and scanning electron microscopy. The two new species, Sinophysis hoppenrathiana sp. nov. and Sinophysis vespertilio sp. nov., were characterized morphologically and shown to differ from all existing species. The cells of S. hoppenrathiana sp. nov. were medium-sized, 32–40 μm long and 23–30 μm deep. They had a peculiar ovate shape, a small crown-like epitheca and the hypotheca was ornamented by shallow alveolae. Cells of S. vespertilio sp. nov. were small, 26–31 μm long and 20–25 μm deep. They were oval in shape...

Dinoflagellates from Red Sea are hardly studied, in particular the benthic forms. Samples collected from shallow intertidal zone, Ain Sokhna, Egypt were microscopically examined. Three genera with seven species were recorded. The most frequently-encountered was Katodinium sp., a small mushroom-like with epitheca being consistently larger than hypotheca. Light micrographs revealed the presence of a nucleus in the hyposome and descending cingulum. Scanning electromicrographs (SEM) confirmed this orientation and revealed the presence of apical pore system. Another species showed similarity to the mushroom-like morphology but with large conical episome and small hyposome. Heterotrophic, naked Gyrodinium cf dominans and Gyrodinium sp. were also observed where in the former, there were conspicuous longitudinal striations. A frequently-observed species had naked Gyrodinium-like morphology but with much smaller size. One photosynthetic species had a characteristic stigma similar to type B eyespot in “dinotoms” and episome being slightly larger than hyposome. Gymnodinium sp. with sulcus extending slightly in the episome but deeply to the end of hyposome was also recorded. This genus is reported to be mostly toxic and its presence should be monitored. Finally, this study presents some early records for benthic dinophytes from rather underexplored locality and raises alerts about genus with reported toxicity.

Species belonging to the dinophyte genus Scrippsiella are frequently reported in marine waters, but information on their distribution in brackish environments is limited. Here we describe a new species, S. plana, through incubation of non-calcified cysts from sediments collected in the South China Sea and Caspian Sea. The vegetative cells consist of a conical epitheca and a rounded hypotheca with the plate formula of Po, X, 4′, 3a, 7′′, 5C+t, 5S, 5′′′, 2′′′′. It differs from other Scrippsiella species by its flattened body in dorsoventral view and a small first anterior intercalary (1a) plate (half the size of plate 3a). Scrippsiella plana strains from the South China Sea and Caspian Sea share identical internal transcribed spacer (ITS) sequences, and show phenotypic plasticity and local adaptation in growth rate at various salinities, consistent with the environments in which they originated. In addition, two strains of S. spinifera were obtained by incubating ellipsoid cysts with calcareous spin...

Dendrophyllia compressa Ogawa and Takahashi, 1995 is newly reported from Korea. The specimen was collected off Seogwipo, Jeju-do, Korea in 1969. It is described herein based on the morphological characters of the skeletal structures. Dendrophyllia compressa is characterized by its small and bushy growth form with branches, vertical growth direction, small calicular diameter, compressed calice, Pourtales Plan with vertical septal inner edges, flat and spongy columella, exserted septal upper margins, and epitheca. Dendrophyllia compressa has been synonymized with Cladopsammia eguchii (Wells, 1982). However, the former species differs from the latter species in its growth form, growth direction, colony size, corallite size, and corallite shape.

Amphidoma is an old though poorly studied thecate dinophyte that has attracted attention recently as a potential producer of azaspiracids (AZA), a group of lipophilic phycotoxins. A new species, Amphidoma parvula, sp. nov. is described from the South Atlantic shelf of Argentina. With a Kofoidean thecal plate pattern Po, cp, X, 6′, 6′′, 6C, 5S, 6′′′, 2′′′′, the cultivated strain H-1E9 (from which the type material of Am. parvula, sp. nov. was prepared) shared the characteristic plate arrangement of Amphidoma each with six apical, precingular and postcingular plates. Amphidoma parvula, sp. nov. differs from other species of Amphidoma by a characteristic combination of small size (10.7–13.6 µm in length), ovoid shape, high length ratio between epitheca and hypotheca, and small length ratio between apical and precingular plates. Other morphological details, such as the number and arrangement of sulcal plates and the fine structure of the apical pore complex support the close relationship between Amphidoma and the other known genus of Amphidomataceae, Azadinium. However, Am. parvula, sp. nov. lacks a ventral pore, a characteristically structured pore found in all contemporary electron microscopy studies of Amphidoma and Azadinium. As inferred from liquid chromatography coupled with tandem mass spectrometry, Am. parvula, sp. nov. did not produce AZA in measurable amounts. Molecular phylogenetics confirmed the systematic placement of Am. parvula, sp. nov. in Amphidoma (as sister species of Amphidoma languida) and the Amphidomataceae. The results of this study have improved the knowledge of Amphidomataceae biodiversity. Fil: Tillmann, Urban. Alfred Wegener Institut; Alemania Fil: Gottschling, Marc. Universität München; Alemania Fil: Guinder, Valeria Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina Fil: Krock, Bernd. Alfred Wegener Institut; Alemania

A heterotrophic dinoflagellate isolated from the waters of Masan Bay, Korea was, at first glance, morphologically similar to Katodinium glandulum, yet had unreported plate patterns and DNA sequences. This dinoflagellate had thin plates arranged in a Kofoidian series Po, X, 4′, 2a, 6″, 6c, PC, 3 + s, 5‴, 0p, and 2⁗, similar to species in the family Pfiesteriaceae. However, it did not have a closing plate (cp) and only small sulcal plates (3 + s). Furthermore, this dinoflagellate had a conspicuous apical hook (finger-like projection) on the epitheca, like K. glandulum and Katodinium asymmetricum, but unlike the other Katodinium species and the other species in the family Pfiesteriaceae. The epitheca had a conical shape and was markedly larger than the hemispherical hypotheca. Cell lengths and widths of live biflagellate cells satiated with the phototrophic dinoflagellate Heterocapsa triquetra were 21.2–29.2 μm and 18.1–24.9 μm, respectively, while those of biflagellate cells starved for 4 d were 10.2–17.3 μm and 7.7–14.6 μm, respectively. The ratio of the width of the epitheca relative to the hypotheca (0.9) is similar to that of K. glandulum, but larger than that of K. asymmetricum (0.5–0.7). The dinoflagellate had a peduncle but lacked an eyespot. The DNA sequences differed from those of K. glaucum, the only Katodinium species with reported rDNA sequences. Compared to the other known genera in the family Pfiesteriaceae, the rDNA sequences of the small subunit (SSU), ITS regions (ITS1, 5.8S, ITS2), and D1–D3 large subunit (LSU) differed by 1.9–6.8%, ≥4.4%, and ≥5.6%, respectively. In a phylogenetic tree based on the SSU and LSU rDNA, a clade containing this species belonged to a larger clade of the family Pfiesteriaceae, but was divergent from a clade containing K. glaucum. Due to its morphological similarity to K. glandulum and genetic differences from K. glaucum and the other species in the family Pfiesteriaceae, it is proposed that this species Aduncodinium glandula be assigned to be a new genus and a new combination, A. glandula.

Trait variation can structure interactions between individuals, thus shaping selection. Although antipredator strategies are an important component of many aquatic systems, how multiple antipredator traits interact to influence consumption and selection remains contentious. Here, I use a common larval dragonfly (Epitheca canis) and its predator (Anax junius) to test for the joint effects of activity rate and algal camouflage on predation and survival selection. I found that active and poorly camouflaged Epitheca were more likely to be consumed, and thus, survival selection favoured inactive and well-camouflaged individuals. Notably, camouflage dampened selection on activity rate, likely by reducing attack rates when Epitheca encountered a predator. Correlational selection is therefore conferred by the ecological interaction of traits, rather than by opposing selection acting on linked traits. I suggest that antipredator traits with different adaptive functions can jointly structure patterns of consumption and selection.

A new photosynthetic, sand-dwelling marine dinoflagellate, Ailadinium reticulatum gen. et sp. nov., is described from the Jordanian coast in the Gulf of Aqaba, northern Red Sea, based on detailed morphological and molecular data. A. reticulatum is a large (53–61 μm long and 38–48 μm wide), dorsoventrally compressed species, with the epitheca smaller than the hypotheca. The theca of this new species is thick and peculiarly ornamented with round to polygonal depressions forming a foveate-reticulate thecal surface structure. The Kofoidian thecal tabulation is APC (Po, cp), 4′, 2a, 6′′, 6c, 4s, 6′′′, 1p, 1′′′′ or alternatively it can be interpreted as APC, 4′, 2a, 6′′, 6c, 4s, 6′′′, 2′′′′. The plate pattern of A. reticulatum is noticeably different from described dinoflagellate genera. Phylogenetic analyses based on the SSU and LSU rDNA genes did not show any supported affinities with currently known thecate dinoflagellates.

New observations on the life cycle stages of Ostreopsis cf. ovata are reported in the field and in cultures samples from the northern Adriatic Sea (Mediterranean Sea). Cultures of O. cf. ovata were performed using both replete and N-free growth media and analyzed for 5 months. Ostreopsis cells displayed a high morphological variability. Some cells were characterized by the presence of orange accumulation bodies, which represented a signal of stress conditions. Two mechanisms of gamete mating seem to occur. In the first (already reported) vegetative cells conjugated through the epitheca without plasmogamy; in this regard we observed a new ‘process’ on the top of the epitheca which might represent a structure involved in this mating mechanism. In the second, small cells acting as gametes were aligned laterally with the two cingula perpendicular to each other. Meiosis possibly occurred as suggested by tetrad formation, originating four vegetative cells. At least two types of cyst were formed, a non-dormant (pellicle) cyst germinating within 2 days and a resting cyst which is able to germinate after a 5-month dormancy only at temperatures over 25 °C.

The dinoflagellate genera Oxytoxum and Corythodinium that account for more than fifty species are widespread in warm oceans. These genera have been considered synonyms and thecal plate designations varied among authors. Several planktonic and sand-dwelling genera have been placed within the Oxytoxaceae. We obtained the first molecular data based on small subunit (SSU) rRNA gene sequences of Oxytoxum and Corythodinium, including the type species (O. scolopax and C. tessellatum) and C. frenguellii and C. cristatum. The three species of Corythodinium branched together a strong support [bootstrap (BP) of 98%]. This formed a sister clade with moderate support (BP 75%) with O. scolopax that supported the generic split. Oxytoxaceae should exclusively remain for Oxytoxum and Corythodinium, as an independent group, unrelated to any other known dinoflagellate. Oxytoxum was characterized by spindle-shaped cells with an anterior narrow epitheca, an apical spine and little cingular displacement. Corythodinium exhibits relatively broad cell shapes, with wider epitheca and greater cingular displacement, and an obovate or pentangular anterior sulcal plate that noticeably indented the epitheca. This suggested the need of new combinations for species that were described as Oxytoxum and possessed the characteristics of Corythodinium.

The genus Scrippsiella contains approximately 20 species that are widespread in coastal and oceanic areas. Classification of Scrippsiella traditionally relied on cyst morphology because the plate pattern was rather conserved. A new species, S. enormis sp. nov. was obtained by incubating a noncalcified cyst from sediments collected in the East China Sea. The vegetative cells consisted of a conical-convex epitheca and a round hypotheca with the plate formula of po, x, 4′, 3a, 7″, 6c (5c+t), 5s, 5‴, 2″″. It differed from other Scrippsiella species by possessing an asymmetrical 1′ and generating noncalcareous, spherical cysts with paratabulation. Phylogenetic analyses based on internal transcribed spacer (ITS) and 5.8S rDNA sequences revealed that S. enormis was nested within the Calciodinellum clade. In addition, two strains of S. cf. spinifera (strains SSFC02, SSFC03) were obtained by incubating calcareous cysts from sediments collected in the South China Sea. They shared identical ITS sequence and formed a...

SUMMARY The dinoflagellate subfamily Diplopsalidoideae encompasses 11 genera whose plate patterns show a large diversity. In a recently published molecular phylogeny (Liu et al. 2015) some of these genera (e.g. Diplopsalis, Diplopelta) are polyphyletic, suggesting that further subdivision of these genera is needed. Here we established the cyst-theca relationship of Diplopsalis caspica by incubating cysts collected from the East China Sea. Cells of D. caspica display a plate formula of Po, X, 3′, 1a, 6″, 3c+t, ?4s, 5″′, 1″″, characterized by a small, parallelogrammic anterior intercalary plate (1a) located in the middle of the dorsal part of the epitheca. The cysts are spherical and smooth-walled with a theropylic archeopyle. In addition, we obtained four large subunit ribosomal DNA (LSU rDNA) sequences from the germinated motile cells by single-cell polymerase chain reaction. Strains of D. caspica from the marine environment of the East China Sea differ at 0–2 positions of LSU rDNA sequences from that of lacustrine strains from NE China. In the molecular phylogeny, D. caspica was close to Lebouraia pusilla but distant from D. lenticula, the type species of Diplopsalis. Our results support the systematic importance of plate 1a, and therefore D. caspica was transferred to a new genus, Huia. The conservative LSU rDNA sequences in H. caspica suggest that the marine-freshwater transition occurred recently.

The new benthic toxic dinoflagellate Ostreopsis fattorussoi sp. nov. is described from eastern Mediterranean Sea Lebanon and Cyprus coasts, supported by morphological and molecular data. The plate formula, Po, 3’, 7’’, 6c, 7s, 5’’’, 2’’’’, is typical for the Ostreopsis genus. It differs from all other Ostreopsis species in that i) the curved suture between plates 1’ and 3’ makes them approximately hexagonal, ii) the 1’ plate lies in the left-half of the epitheca and is obliquely orientated leading to a characteristic shape of plate 6’’. The round thecal pores are bigger than the other two Mediterranean species (O. cf. ovata and O. cf. siamensis). O. fattorussoi is among the smallest species of the genus (DV: 60.07±5.63 μm, AP: 25.66±2.97 μm, W: 39.81±5.05 μm) along with O. ovata. Phylogenetic analyses based on the LSU and ITS rDNA shows that O. fattorussoi belongs to the Atlantic/Mediterranean Ostreopsis spp. clade separated from the other Ostreopsis species. O. fattorussoi produces OVTX-a and structural isomers OVTX-d and –e, O. cf. ovata is the only other species of this genus known to produce these toxins. The Lebanese O. fattorussoi did not produce the new palytoxin-like compounds (ovatoxin-i, ovatoxin-j1, ovatoxin-j2, and ovatoxin-k) that were previously found in O. fattorussoi from Cyprus. The toxin content was in the range of 0.28-0.94 pg. cell−1. In Lebanon coast, O. fattorussoi was recorded throughout the year 2015 (temperature range 18-31.5 °C), with peaks in June and August. This article is protected by copyright. All rights reserved.

We used a time-lapse imaging approach to examine cell division in the marine centric diatom Ditylum brightwellii and observed that daughter cells who inherited their parents’ hypothecal frustule half were more likely to divide before their sisters. This is consistent with observations in Escherichia coli of a bias between sister cells, where faster growth in one sister is thought to arise from its inheriting parental material with less oxidative damage. We also observed that hypothecal sisters in D. brightwellii were more likely to inherit a greater proportion of their parents’ cellular material, similar to what has been seen in E. coli. We found a statistically significant correlation between the amount of parental material inherited by a hypothecal daughter and its relative division rate, indicating that this extra material inherited by the hypothecal daughter plays a role in its more rapid division. Furthermore, the intercept in this regression was greater than zero, indicating that other factors, such as differences in the quality of inherited material, also play a role. This similarity between two taxonomically distant microbes suggests that favoritism toward one daughter might occur broadly among unicellular organisms that reproduce asexually by binary fission. Such a bias in cell division might be advantageous, given model predictions that show that favoring one daughter at the expense of the other can result in higher population growth rates, increasing the chance that a cell’s genotype will survive compared to a model where the daughters divide at equal rates. Many unicellular organisms reproduce primarily by binary fission, an asexual process in which a parent cell undergoes first mitosis, then cytokinesis, to form two new daughter cells. Mitosis ensures that these sister cells are effectively identical in terms of genotype, but it is likely that they will differ at least slightly in phenotype. Phenotypic differences between two nascent sister cells can arise from stochastic effects during cell division that result in the inexact division of parental material between the two progeny. Non-stochastic mechanisms can also bias the allocation of parental material between two sister cells, sometimes systematically and predictably. The degree to which phenotypic differences occur between sister cells— and whether these differences reflect purely stochastic or instead biased processes—may have important consequences not only to the relative growth and fitness of these two cells as individuals, but also at the population level, depending on how these between-sister asymmetries are manifested. A well-known example of a systematic, between-sister phenotypic asymmetry is seen in the diatoms, arising from the morphology of their rigid exterior frustules. Diatom frustules are composed of two halves of slightly different diameters, and during cell division one daughter inherits the parent’s larger-diameter epithecal half and its sister inherits the smaller-diameter hypothecal half. Each daughter then forms a new hypotheca to fit inside whichever frustule half it inherited (Macdonald 1869; Pfitzer 1869). A consequence of this between-sister morphological asymmetry is that the sister inheriting the epitheca will be the same diameter as its parent and the other will be slightly smaller. Although this difference in diameter is slight, over many generations it will lead to the well-known diminution in cell

Samples of free-living corals of Favia gravida (Scleractinia: Faviidae) have been studied. They were collected from an intertidal rock pool on Ascension Island, southern Atlantic Ocean. They consist of phaceloid clusters of corallites that appear to be able to easily break apart from each other by the formation of slits inbetween them, which indicates the occurrence of asexual reproduction by fragmentation. The base of the fragments is usually tapering or conical and covered by an epitheca. Small corallites on the base of some specimens suggest that the corals also reproduce by budding. By not depending on a solid substratum for reproduction, the corals appear to be utterly adapted to a free mode of life. These traits have not been reported before from Favia, which normally consists of massive corals. The variable shape of the corals at hand indicate that they have adopted a plastic free-living growth form that appears to be confined to a rock pool habitat.

Seilacher, A. & Thomas, R.D.K. 2011: Self-organization and emergent individuality of favositid corals adapted to live on soft substrates. Lethaia, Vol. 45, pp. 2–13. Secondary soft-bottom dwellers share the problem that their ancestors, attached to hard substrates, had lost their mobility. On soft substrates, only a limited number of alternative tricks are available to maintain sessile organisms in life position or to right them following disturbance. Consequently, convergent adaptations have emerged in unrelated members of this ecological guild. Those of favositid corals are of particular interest because, on account of their small polyps, they were always colonial. A comparative analysis of forms adopted by favositids on soft substrates shows that key elements of their adaptive paradigms could have been achieved by self-organization. This arose without centralized control by means of inherited reaction norms of individual polyps to local environmental conditions. The unique spiral growth habit of Favosites turbinatus Billings and its emergent individuality at the colony-level of organization are explained in these terms. ‘Suicidal’ lids entombed altruistic marginal polyps, forming a secondary epitheca as the growing colony settled into the sediment. These lids also record the size and spacing of soft tentacles in this species. □Coloniality, Devonian, Favositida, Favosites turbinatus, morphogenesis, self-organization, Tabulata.

Research on very fine fossil corals from Shiqiantan Fm, Xinjiang (310Ma) which have very clear growth lines caused by diurnal increments of calcium carbonate deposition provides important information about ancient climate. This result breaks the record of the oldest remaining material for detailed climate analysis. Data showed distinct seasonal variations, separating ancient climate into four seasons. Storms are frequent in summer during at that time. And the sea temperature exceeded ~30°C for a month in mid-summer. Equipped with this new method, a specific day’s climate, cloudy or shining, can be studied from the diurnal patterns.

Odonates are vulnerable during emergence, when they shed their larval skin (exuvia) to take flight as adults. Emergence-site selection should adapt to the local mortality risks. Here, I characterized emergence-site selection of Epitheca spinosa (Robust Baskettails) by noting the substrate, height, and distance from water of exuviae in a 300 m × 5 m plot at Weston Lake, Congaree National Park, Hopkins, SC. Of the 82 Robust Baskettail exuviae sampled, 52 (63.4%) were found on trees with corky bark (Nyssa aquatica [Water Tupelo], Nyssa biflora [Swamp Tupelo], Fraxinus pennsylvanica [Green Ash]), while no exuviae were found on the peeling, flaky trunks of Taxodium distichum (Bald Cypress) or the smooth, platy trunks of Acer rubrum (Red Maple). However, 26 (31.7%) exuviae were on T. distichum pneumatophores. This pattern was significantly different from the relative abundances of these substrate types (χ2 = 19.8, df = 3, P < 0.001). Most exuviae (93.9%) were on substrates touching the water, suggestin...

Dixon, O.A. 2010: Fossilized polyp remains in Silurian Heliolites (Anthozoa, Tabulata) from Nunavut, Arctic Canada. Lethaia, Vol. 43, pp. 60–72. Calices within a substantially silicified corallum of Heliolites garnieriDixon, 1996, from the lower part of the Barlow Inlet Formation (Ludlow) on south-western Devon Island, contain what appear to be the silicified remains of soft tissues of coral polyps. These remains apparently represent the peristomal portion of an oral disc, incorporating a symmetrical radial array of 12 spicules (intra-polyp sclerites), and a membrane-like, possibly epidermal structure. These remains, and more non-descript material in a few coralla belonging to two other species of Heliolites, occur at local intra-corallum discontinuities where polyps died, but the surrounding colony continued skeletal construction. Their preservation indicates that, before the organic remains were fully destroyed by decomposition, they were rapidly enclosed and sealed by precipitation of microcrystalline quartz or a precursor, and that the failed calices were capped rapidly by local construction of basal epitheca. Clusters of hollow microspheres were also preserved at these discontinuities, suggestive of micro-organisms with a predilection for sites of tissue decay; these microbial decay agents possibly helped to isolate microenvironments conducive to early precipitation of silica. □Canada, Heliolitidae, microspheres, Nunavut, silicified polyp remains, Silurian, Tabulata.

The name Peridinium palatinum Lauterborn currently designates a freshwater peridinioid with 13 epithecal and six cingular plates, and no apical pore complex. Freshwater dinoflagellate floras classify it in Peridinium group palatinum together with P. pseudolaeve M. Lefevre. General ultrastructure, flagellar apparatus, and pusular components of P. palatinum were examined by serial section TEM and compared to P. cinctum (O. F. Mull.) Ehrenb. and Peridiniopsis borgei Lemmerm., respectively, types of Peridinium and Peridiniopsis. Partial LSU rDNA sequences from P. palatinum, P. pseudolaeve and several peridinioids, woloszynskioids, gymnodinioids, and other dinoflagellates were used for a phylogenetic analysis. General morphology and tabulation of taxa in group palatinum were characterized by SEM. Differences in plate numbers, affecting both the epitheca and the cingulum, combine with differences in plate ornamentation and a suite of internal cell features to suggest a generic-level distinction between Peridinium group palatinum and typical Peridinium. The branching pattern of the phylogenetic tree is compatible with this conclusion, although with low support from bootstrap values and posterior probabilities, as are sequence divergences estimated between species in group palatinum, and typical Peridinium and Peridiniopsis. Palatinus nov. gen. is proposed with the new combinations Palatinus apiculatus nov. comb. (type species; syn. Peridinium palatinum), P. apiculatus var. laevis nov. comb., and P. pseudolaevis nov. comb. Distinctive characters for Palatinus include a smooth or slightly granulate, but not areolate, plate surface, a large central pyrenoid penetrated by cytoplasmic channels and radiating into chloroplast lobes, and the presence of a peduncle-homologous microtubular strand. Palatinus cells exit the theca through the antapical-postcingular area.

Colonization by the zebra mussel, Dreissena polymorpha, was quantified for five dragonfly species that differed in size and larval habits in a Michigan lake. Both larger size and a non-burrowing habit independently increased susceptibility to colonization. In 2005, over 50% of the final instars of the sprawlers Didymops transversa and Hagenius brevistylus were colonized, as well as younger instars. Rarely colonized were Progomphus obscurus and Dromogomphus spinosus, whose larvae burrow under sand, and the sprawler Epitheca princeps, whose final instars were lightly covered with sand. Hagenius larvae that had been preyed upon carried more mussels than those dying of other causes. More generally, mussel attachment decreased the probability that sprawlers left the water to emerge, the distance that some species traveled before emerging, and the ability of an overturned sprawler to right itself. On average, final instars of Didymops and Hagenius remaining in the water carried three times as many mussels as individuals known to emerge. Compared to uncolonized individuals, Epitheca and Progomphus with mussels emerged closer to the water line. Among colonized Didymops, the distance traveled on land before emerging decreased with increasing mussel load. Of the colonized Didymops that could right themselves, righting time increased with mussel load. Because the two common species of sprawlers were disproportionately colonized, and mussel attachment decreased their chances of emerging, our results suggest that D. polymorpha has the potential to affect the community structure of this guild of aquatic and terrestrial predators.

A new freshwater phototrophic species of the dinoflagellate genus Peridiniopsis, P. niei sp. nov., is described based on morphology. The new species appeared during spring with densities up to 1.48 x 10(7) cells L-1 in some tributaries and gullies of Three Gorge Reservoir and Lake Donghu, China, forming red tides. Peridiniopsis niei is a cyst-producing freshwater dinoflagellate that belongs to the group Penardii. The plate tabulation is po+x+4 '+0a+6 ''+5c+5s+5 '''+2 '''' and the plate pattern is symmetric. The cells of P. niei are pentagonal in ventral view, the epitheca is larger than the hypotheca, making up about 2/3 the length of the cell. Plate 3 ' is hexangular. The closest species to P. niei is P. penardii (Lemmermann) Bourrelly, but cells of the former are pentagonal, very compressed dorsoventrally, and the hypotheca is truncated with one transparent, robust spine on each antapical plate.

Physiological responses to environmental stress are increasingly well studied in scleractinian corals. This work reports a new stress-related skeletal structure we term clypeotheca. Clypeotheca was observed in several live-collected common reef-building coral genera and a two to three kya subfossil specimen from Heron Reef, Great Barrier Reef and consists of an epitheca-like skeletal wall that seals over the surface of parts of the corallum in areas of stress or damage. It appears to form from a coordinated process wherein neighboring polyps and adjoining coenosarc seal themselves off from the surrounding environment as they contract and die. Clypeotheca forms from inward skeletal centripetal growth at the edges of corallites and by the merging of flange-like outgrowths that surround individual spines over the surface of the coenosteum. Microstructurally, the merged flanges are similar to upside-down dissepiments and true epitheca. Clypeotheca is interpreted primarily as a response to stress that may help protect the colony from invasion of unhealthy tissues by parasites or disease by retracting tissues in areas that have become unhealthy for the polyps. Identification of skeletal responses of corals to environmental stress may enable the frequency of certain types of environmental stress to be documented in past environments. Such data may be important for understanding the nature of reef dynamics through intervals of climate change and for monitoring the effects of possible anthropogenic stress in modern coral reef habitats.

Resting cysts of the marine phytoplanktonic dinoflagellate Scrippsiella spp. are encountered in coastal habitats and shallow seas all over the world. Identification of Scrippsiella species requires information on cyst morphology because the plate pattern of the flagellated cell is conserved. Cysts from sediments of the East China Sea were identified based on traits from both the cysts and the thecal patterns of germinated cells. Calcareous cysts belonged predominantly to S. trochoidea (F. Stein) A. R. Loebl., S. rotunda J. Lewis, and S. precaria Montresor et Zingone. The former two species also produced smooth and noncalcified cysts in the field. A new species, S. donghaienis H. Gu sp. nov, was obtained from six noncalcified cysts with organic spines. These cysts are spherical, full of pale white and greenish granules with a mesoepicystal archeopyle. The vegetative cells consist of a conical epitheca and a round hypotheca with a plate formula of po, x, 4', 3a, 7 '', 6c (5c + t), 6 s, 5''', 2'''' and are morphologically indistinguishable from S. trochoidea. Results of internal transcribed spacer (ITS) sequence comparisons revealed that S. donghaienis was distinct from the S. trochoidea complex and appeared nested within the Calciodinellum/Calcigonellum clade. Culture experiments showed that the presence of a red body in the cyst and the shape of the archeopyle were constant within cell lines from one generation to the next, while the morphological features of the cyst wall, such as calcification and spine shape, appeared to be phenotypically plastic.

Examples of rarely reported dinoflagellates of the family Kofoidiniaceae F.J.R. Taylor (Noctilucales) from the northwest, equatorial and southeast Pacific Ocean are described and illustrated. Kofoidinium was the most ubiquitous genus with a maximum abundance of 10 cells L(-1). Specimens of this genus were identified to four species: Kofoidinium sp. that showed a pointed extension that emerges from the antero-ventral region and K. velelloides, both of which had diameters that ranged from 40 to 200 microm; Kofoidinium pavillardii which showed a rounded epitheca and a larger size (approximately 300-700 microm in diameter); and another species, tentatively identified as K. splendens, that contained red circular inclusions. Further research is needed to clarify the characteristics that separate K. splendens from the other species. This study is the first to record the genus Spatulodinium in tropical waters and in the southern hemisphere. S. cf. pseudonoctiluca was found in the southeast Pacific Ocean, as well as other smaller specimens with a different shape or disposition of the tentacle that may belong to two other species. In the northwest and equatorial Pacific, specimens of Spatulodinium showed a green pigmentation that suggested the existence of the first species known in the order Noctilucales to contain its own chloroplasts. Immature stages of kofoidiniaceans, some containing symbiotic microalgae, are illustrated, as well as mature stages related to Pomatodinium and to unknown genera of kofoidiniaceans. Kofoidiniaceans are shown to be common and widely distributed in the Pacific, and are probably also frequent in other oceans, but are rarely recognised.

A new species of the dinoflagellate genus Gymnodinium Stein, previously considered a member of Katodinium Fott, is characterized from two marine benthic habitats in tropical northern Australia. Gymnodinium dorsalisulcum comb. nov. was found to be very abundant at times, and in culture produced large quantities of mucus. We analyzed two regions of ribosomal DNA from this species (partial large subunit and complete small subunit sequences), using Bayesian analysis and phylogenetic models appropriate to alignments of ribosomal RNA genes. We compared it to eight species of the ‘true’ Gymnodinium clade and to other dinoflagellates. The results show that it is a member of the Gymnodinium clade, and is closely related to Gymnodinium impudicum and G. chlorophorum. Katodinium was originally defined as having cells with an epitheca that is much larger than the hypotheca. However, this character is clearly inadequate, and the genus requires a re-investigation to determine the apomorphies of the type species.

Defined by its unique colonial locomotion, Bacillaria paxillifer (O. F. Mull.) Hendey was recognized as a single, pandemic species by many phycologists. However, reinvestigation of colonies from different habitats revealed three distinct groups: (A) brackish/freshwater, (B) marine littoral, and (C) marine planktonic taxa. Groups differed in colony and cell form, raphe flanges (RFs), shape and position of transapical ribs (Tr's), and morphogenesis. Linear-shaped species were restricted to group A: Tr's thickened principally to the interior. Lanceolate forms were confined to groups B and C: valve formation proceeded from an internal base layer to the exterior. The planktonic species differed in the shape of its raphe slit, and the transformation of girdle bands (GBs) into “winglets.” Taxa also differed in chloroplast shape and number. All species formed motile colonies. Siblings adhered via elastic fibrils secreted through their raphe. Raphe ribs were held in position by siliceous clamps (fibulae), anchored in an extra pair of axial ribs (fibular ribs) parallel to the raphe ribs. This raphe system resembled that of Cylindrotheca rather than the “canal raphe” of Nitzschia. Many valves were asymmetric along the apical axis due to protruding RFs shuttling in a 1:1 ratio within a colony, but raphe slits were mirror images, as were the growth direction of fibulae and position of plastids, with pyrenoids tilted in the same direction. Species possessed four open GBs per epitheca; the third band invariably bore an internal, organic ridge to aid in adhesion of the plasmalemma during cleavage. The results suggested that these taxa are a natural phylogenetic group, requiring precise determination of their taxonomic position.

The marine epiphytic dinoflagellate Gambierdiscus is a toxicologically important genus responsible for ciguatera fish poisoning, the principal cause of non-bacterial illness associated with fish consumption. The genus currently contains species exhibiting either globular or anterior-posteriorly compressed morphologies with marked differences in cell shape and plate arrangement. Here we report a third globular, epiphytic and tychoplanktonic species from the coasts of Ubatuba, Brazil. The new species can be distinguished from G. yasumotoi and G. ruetzleri by its broader first apical plate that occupies a larger portion of the epitheca. Accordingly, phylogenetic trees from small subunit (SSU) and large subunit (LSU) ribosomal DNA sequences also showed strongly supported separation of the new species from the G. yasumotoi / G. ruetzleri group albeit with short distance. The molecular phylogenies, which included new sequences of the planktonic species Goniodoma polyedricum, further indicated that the globular species of Gambierdiscus formed a tight clade, clearly separated (with strong bootstrap support) from the clade of lenticular species including the type for Gambierdiscus. The morphological and molecular data in concert support the split of Gambierdiscus sensu lato into two genera. Gambierdiscus sensu stricto should be reserved for the species with lenticular shapes, highly compressed anterioposteriorly, with short-shank fishhook apical pore plate, large 2' plate, low and ascending cingular displacement, and pouch-like sulcal morphology. The new genus name Fukuyoa gen. nov. should be applied to the globular species, slightly laterally compressed, with long-shank fishhook apical pore plate, large 1' plate, greater and descending cingular displacement, and not pouch-like vertically-oriented sulcal morphology. Fukuyoa contains the new species Fukuyoa paulensis gen. et sp. nov., and F. yasumotoi comb. nov. and F. ruetzleri comb. nov.

One species ofMicrotabella,Microtabella interrupta, is widespread and has been known since the 19th Century but it has a convoluted taxonomic history leaving it presently the only species in the genus. The nameinterruptaderives from the chain-forming habit and the plastids being confined to a portion of the cell by a set of distinctively distended septa. This character makes it very easy to identify and very easy to overlook similar species, especially because the tabulate frustules are most often seen in girdle view. I found specimens of a new taxon that had these characters and was distinguished with difficulty in girdle view by the coarser striae on the copulae and the recurved edges of the septa. However, in valve viewMicrotabella rhombican. sp. has a much broader, rhombic outline. Ultrastructural differences include a more elongated apical pore field with a prominent spine, biseriate striae on the copulae and a different form of the ligule (a raised bar on the last copula). LikeMicrotabella interrupta, the mature epitheca ofMicrotabella rhombicacomprises numerous copulae with nearly flat septa, two copulae with distended septa and four hyaline pleurae that lack septa. This species could well be widespread but, as with other monospecific genera in which there is a strong distinguishing character, care must be taken to look beyond the outstanding feature.

A variety of studies have examined the sexual life cycle of species belonging to the genus Dinophysis Ehrenberg. Here, we used TEM to investigate the mechanism of cellular fusion during the sexual life cycle in Dinophysis fortii Pavillard. We observed that fusion always occurred between a normal-sized cell and a small cell following attachment of their ventral margins. After cell attachment, the small cell moved toward the epitheca of the normal-sized cell, and the cingular and sulcal lists of the small cell shrunk or were almost lost. The epitheca of the normal-sized cell then opened between the cingulum plates and the upper cingular list, after which the small cell was gradually engulfed. This is the first ultrastructural observation in a dinoflagellate of a larger cell opening its epitheca to engulf the smaller gamete. In another case, the normal-sized cell did not open the epitheca, the cell wall of the attached small cell underwent extensive extracellular digestion, and the cytoplasm appeared to flow into the normal-sized cell via the periflagellar area. Inflow of the nucleus was not observed in this case, suggesting that it represented a failure of sexual fusion. In both cases, membranous separations between the cytoplasm of the two cells were not observed. At the beginning of the fusion process, the nucleus of the small cell was substantially deformed. The planozygote, formed upon completion of sexual fusion, sometimes had two longitudinal flagella, but was identical to a normal vegetative cell in its cellular shape, as already mentioned by previous authors.

This study carried out phylogenetic analysis of dinoflagellate Gonyaulax polygramma which was responsible for a harmful algal bloom episode in Korea in 2004. Molecular phylogenetic tree inferred from the partial LSU rDNA data showed that G. polygramma came up among the monophyletic Gonyaulax clade, but did not have apparent genetic affiliation to other Gonyaulax species. This result appears to be consistent with characteristic morphological features of G. polygramma such as epitheca sharply tapering to the apex and thecal plates ornamented with numerous longitudinal striations.