Abstracts of Papers read at the Winter Meeting at Queen Elizabeth College,London

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.     

DESCRIPTION OF THECADINIUM MUCOSUM SP. NOV. (DINOPHYCEAE), A NEW SAND‐DWELLING MARINE DINOFLAGELLATE,AND AN EMENDED DESCRIPTION OF THECADINIUM INCLINATUM BALECH1

A new thecate, phototrophic, marine, sand‐dwelling dinoflagellate, Thecadinium mucosum Hoppenrath et Taylor sp. nov., is described from a culture isolated from Boundary Bay, British Columbia, Canada. It was illustrated with LM as well as SEM and TEM, and its position in the phylogenetic tree of dinoflagellates was investigated using molecular methods. Cells are asymmetrical, oval, laterally flattened, and strongly pigmented, with the plate formula P 3′ 1a 6′′ 7/8c 5 s 6′′′ 2′′′′. Thecal plates are smooth with scattered pores, and there is a distinctive anterior intercalary plate that could be involved in mucus secretion. Thecadinium inclinatum Balech (=Sabulodinium inclinatum (Balech) Saunders et Dodge), a thecate, marine, sand‐dwelling species that has been previously confused with what we now call T. mucosum, was also examined and illustrated through LM and SEM. New information on T. inclinatum is provided, including its plate formula P 3′ 6′′ 7c ?s 5′′′ 1p 1′′′′; we consider T. inclinatum to be related to most other Thecadinium species and not to Sabulodinium. Molecular phylogenetic analyses based on the small subunit ribosomal gene of T. mucosum, T. kofoidii (the type species of the genus), and T. dragescoi weakly support earlier suspicions based on morphology that T. dragescoi is not a member of Thecadinium. Tabulational patterns of the species suggest a relationship to the genus Amphidiniopsis.     

Light and scanning microscopy of two benthic species of Amphidiniopsis (Dinophyceae), Amphidiniopsis hexagona sp. nov. and Amphidiniopsis swedmarkii from Japan

Two species of the genus Amphidiniopsis, a marine armoured, sand‐dwelling dinoflagellate, Amphidiniopsis hexagona Yoshimatsu, Toriumi et Dodge sp. nov. and Amphidiniopsis swedmarkii (Balech) Dodge were collected from Japanese sandy beaches, and their morphologic features were observed by light microscopy and scanning electron microscopy. Amphidiniopsis hexagona was hexagonal in ventral view and measured 44–59 urn in length and 40–53 urn in width. The plate formula is P_o, 4′, 2a, 7″, 3c, 4s (+ 2 accessory), 5″″, 2″″. This plate arrangement of A. hexagona is essentially the same as those of Amphidiniopsis hirusta and A. swedmarkii, but this new species can be readily distinguished from the latter two species by the following characters: (i) the cell shape; (ii) the presence of an antapical spine; and (iii) the surface ornamentation of thecal plates.     

Morphology and spatial distribution of Cabra species (Dinophyceae,Peridiniales) from Peter the Great Bay (northwestern Sea of Japan), including the description of C. levis sp. nov.

Two species of the marine sand-dwelling dinoflagellate genus Cabra were found in epiphytic assemblages on macrophytes from Peter the Great Bay of the Sea of Japan: the type species of the genus Cabra matta and a new species Cabra levis sp. nov. The new species possesses all characteristics of the genus, e.g. the same plate formula (APC 3′ 1a 5′′ 3c 6s 5′′′ 1′′′′), and is 29.0–42.0 µm long and 24.6–37.8 µm deep. It differs from other Cabra species by its more rounded shape, in lacking a spine on the dorsal side of the cell and a pointed flange on plate 1′′′, in having nearly smooth thecal plates as well as by the position of the epithecal plates. Some details of the sulcal construction of Cabra species are described for the first time. Cabra levis and C. matta were found on macrophytes throughout the year. As both species occurred more often on macrophytes than in near-shore sand, they are epiphytic rather than sand-dwelling.     

Haramonas viridissp. nov. (Raphidophyceae, Heterokontophyta), a new sand-dwelling raphidophyte from cold temperate waters

A new, marine, sand‐dwelling raphidophyte from Sylt, Germany, Haramonas viridis Horiguchi et Hoppenrath sp. nov. is described. This represents a second species in the previously monotypic genus Haramonas, which was originally described from a sand sample from a mangrove river mouth in tropical Australia, based on the type species, H. dimorpha. This new species from a cold temperate region: (i) possesses a tubular invagi‐nation in the posterior part of the cell; (ii) produces copious amounts of mucilage in culture; (iii) possesses both motile and non‐motile stages in its life cycle; and (iv) has overlapping discoidal chloroplasts, all of which are diagnostic features of the genus Haramonas. Therefore, it is indisputable that this species belongs to this genus. However, the species from Sylt differs from the type species of the genus in: (i) having a larger cell size; (ii) possessing a larger number of chloroplasts; and (iii) being greenish in color. The ultrastructural study revealed that the structure of the tubular invagi‐nation was the same as that of the type species.     

MORPHOLOGY AND ECOLOGY OF THE MARINE DINOFLAGELLATE OSTREOPSIS LABENS SP. NOV. (DINOPHYCEAE)1

A new species, Ostreopsis labens Faust et Morton sp. nov., is described from three marine habitats: lagoonal water and lagoonal sand from the barrier reef of Belize, and associated with macroalgae from coral reef habitats of Oshigaki and Iriomote Islands, Japan. Dimensions of Ostreopsis labens cells are 60–86 μm long, 70–80 μm wide, and 81–110 μm in dorsoventral depth. Cells are broadly ovoid, anterioposteriorly compressed bearing a spherical nucleus and many chloroplasts. The epitheca is convex and composed of three apical plates, seven precingular plates, and an apical pore plate. The cingulum is composed of six plates. The hypotheca is constructed of five postcingular plates, one posterior intercalary, and two antapical plates. The sulcus is small, recessed, and hidden and exhibits a ventral pore and a ridged, curved plate. The thecal arrangement of O. labens is P_o, 3′, 7″ 6C, 6S(?), V_p, R_p, 5″, 1p, 2″. Only one sulcal list is present. The thecal plates have a smooth surface with distinct round pores. The intercalary band between the thecal plates is smooth. A row of marginal pores line the lipped cingulum. Ostreopsis species are anteroposteriorly flattened, photosynthetic, benthic dinoflagellates that are more diverse in ecology than previously known. Ostreopsis labens is capable of living in three marine habitats: in the water column, in sand, and on macroalgal surfaces. It was most numerous in sand and less in lagoonal waters, and only a few cells were associated with macroalgae. Light and scanning electron microscopy studies revealed engulfed cells within O. labens, which indicates mixotrophic/phagotrophic behavior. A ventral opening situated in the cingulum of O. labens exhibits size variability; it may serve as an opening for engulfiing food particles because it varies in size. We propose that ingestion of prey by O. labens occurs through the ventral opening, the proposed feeding apparatus of this species, which is similar to the function of the peduncle-like structure of mixotrophic dinoflagellates. The behavior of O. labens appears similar to that previously described for Dinophysis species.     

Vermistella arctica n. sp. Nominates the Genus Vermistella as a Candidate for Taxon with Bipolar Distribution

A new amoebozoan species, Vermistella arctica n. sp., is described from marine habitats in the central part of Svalbard archipelago. This is the first report on Arctic amoebae belonging to the genus Vermistella Moran and Anderson, 2007, the type species of which was described from the opposite pole of the planet. Psychrophily proved in the new strains qualifies the genus Vermistella as a bipolar taxon. Molecular phylogenetic analyses based on 18S rDNA and actin sequences did not show any affinity of the genus Vermistella to Stygamoeba regulata ATCC^® 50892^? strain. A close phylogenetic relationship was found between Vermistella spp. and a sequence originating from an environmental sample from Cariaco basin, the largest marine permanently anoxic system in the world. Possible mechanisms of bipolar distribution are discussed.     

Phylogenetic study of benthic, spine-bearing prorocentroids, including Prorocentrum fukuyoi sp. nov.

Species of prorocentroid dinoflagellates are common in marine benthic sediment and epibenthic habitats, as well as in planktonic habitats. Marine planktonic prorocentroids typically possess a small spine in the apical region. In this study, we describe a new, potentially widely distributed benthic species of Prorocentrum, P. fukuyoi sp. nov., from tidal sand habitats in several sites in Australia and from central Japan. This species was found to possess an apical spine or flange and was sister species to P. emarginatum. We analyzed the phylogeny of the group including this new species, based on large subunit (LSU) rDNA sequences. The genus contained a high level of divergence in LSU rDNA, in some cases among sister taxa. P. fukuyoi and P. emarginatum were found to be most closely related to a clade of generally planktonic taxa. Several morphological features may constitute more informative synapomorphies than habitat in distinguishing clades of prorocentroid species.     

Plagiodinium ballux sp. nov. (Dinophyceae), a deep (36 m) sand dwelling dinoflagellate from subtropical Japan

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 μm 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.     

FURTHER SEM STUDY OF MARINE DINOFLAGELLATES: THE GENUS OSTREOPSIS (DINOPHYCEAE)1

This paper presents a comprehensive examination of the taxonomy of the genus Ostreopsis Schmidt. The morphology of six species of marine dinoflagellates, Ostreopsis siamensis Schmidt 1902. Ostreopsis lenticularis Fukuyo 1981, Ostreopsis ovata Fukuyo 1981, Ostreopsis heptagona Norris, Bomber, et Balech 1985, Ostreopsis mascarenensis Quod 1994, and Ostreopsis labens Faust et Morton 1995 from three geographical regions (Japan, Southwest Indian Ocean, and the Caribbean) and three marine habitats (sand, water column, and macroalgal surfaces) are described from scanning electron micrographs. Differences in the following morphological characteristics differentiated the species: cell shape and size, and ornamentation of the epitheca, cingulum, and hypotheca. The thecal plate formula of the six Ostreopsis species is P_o, 3′, 7″, 6C, 6S?, V_p, R_p, 5′″, 1p, 2″″, with differences in thecal plate size and shape. The cingulum in ventral view has two prominent structures: a ventral plate (V_p) with a ventral pore (V_o) and a ridged plate (R_p) that distinguishes Ostreopsis species from any other dinoflagellate taxa. This paper also includes ecological and toxicity information regarding the six Ostreopsis species.     

OBSERVATION OF SAND-DWELLING TOXIC DINOFLAGELLATES (DINOPHYCEAE) FROM WIDELY DIFFERING SITES, INCLUDING TWO NEW SPECIES

Dinoflagellate associations, including toxic and potentially toxic benthic species, were examined in sand from South Water Cay and Carrie Bow Cay, Belize. The inshore sand habitat in localized areas of warm shallow lagoonal waters supported blooms of toxic assemblages of dinoflagellates. In the sand, the dominant microalgae were dinoflagellates; cyanobacteria were a minor component and diatoms were absent. Ciliates and nematodes were present. Assemblages of microorganisms in colored sand were examined for 4 consecutive days after which a storm washed away the patch. The sand-dwelling dinoflagellate assemblage included 16 species where densities ranged from as low as 1.3% to 15% of total cell densities. The dominant species was Scrippsiella subsalsa, having 1.8 × 10⁵ to 2.6 × 10⁵ cells g^-1 sand. Toxic dinoflagellates identified in the sand were Gambierdiscus toxicus, Ostreopsis lenticularis, Prorocentrum lima, Prorocentrum mexicanum, and Amphidinium carteri. The potentially toxic Ostreopsis labens, Gambierdiscus belizeanussp. nov., and Coolia tropicalis sp. nov. were also identified. Toxic and potentially toxic species represented 36% to 60% of total microalgal cell assemblage. The morphology of a new sand-dwelling species, Gambierdiscus belizeanus sp. nov., was examined with the scanning electron microscope. The plate formula was P_o, 3′, 7″, 6c, s?, 5?, 1p, and 2″″.Dimensions of G. belizeanus cells were 53–67 pm long, 54–63 μm wide, and 92–98 μm in dorsoventral depth. Cells were deeply areolated, ellipsoid in apical view, and compressed anteroposteriorly. The cells of G. belizeanus were identified by the cell's long, narrow, pentagonal, posterior intercalary plate (1p) wedged between the wide postcingular plates 2″’and 4″; 1p occupied 20% of the width of the hypotheca. The plate formula for Coolia tropicalis sp. nov. was P_o, 3′, 7″, 7c, 8s?, 5″″, and 2″″, Cell size ranges were 23–40 μm long, 25–39 μm wide, and 35–65 μm in dorsoventral diameter. Cells were spherical, smooth, and covered with scattered round pores. The epitheca was smaller than the hypotheca. Precingular plates 1″ and 7″ were small and narrow, and the first apical plate 1″ and precingular plate 6″ were the largest plates on the epitheca. The apical pore was straight and 7 μm long, and was situated in the apical plate complex. Cells of C. tropicalis were distinguished from C. monotis by the wedge-shaped plate 1′, a four-sided 3’plate, and a short apical pore.     

ULTRASTRUCTURE OF PRYMNESIUM NEMAMETHECUM SP. NOV. (PRYMNESIOPHYCEAE)1

Based on material collected from Cape Town, a new sand-dwelling, marine species of Prymnesium is described. Using light and electron microscopy, Prymnesium nemamethecum sp. nov. has been found to resemble other species of the genus in size, organelle arrangement, and swimming behavior. It differs from other described species in that it has three types of scales, one of which is confined to the region of appendage insertion and forms a sheath of simple plate scales over the haptonema. In addition, the scales constituting the proximal body scale layer(s) are unusual because they are not simple plate scales but are specifically ornamented.     

Morphology and taxonomy of five marine sand-dwelling Thecadinium species (Dinophyceae) from Japan, including four new species: Thecadinium arenarium sp. nov., Thecadinium ovatum sp. nov., Thecadinium striatum sp. nov. and Thecadinium yashimaense sp. nov.

Thecadinium inclinatum Balech and four new marine sand‐dwelling species of the dinoflagellate genus Thecadinium are described from the sandy beaches along the coast of Shikoku, Japan. Thecadinium inclinatum is thecate, bilaterally flattened, elliptical in shape, non‐photosynthetic, and measures 55–75 μ in length and 43–59 μ in depth. The epi‐ and hypotheca theca are semielliptical and the thecal surface is smooth with small pores. The plate formula is Po (pore plate), 3′, 7″,?c,?s, 5″′1″′.Thecadinium ovatum sp. nov. is thecate, non‐photosynthetic, bilaterally flattened and almost oval in lateral view. The cell measures 40–50 μm in length and 33–40 μm in depth. The hypotheca has two or three strong antapical spines. The plate formula is 3′, 6″,6c, 5s?, 5″′, 1″′. Thecadinium striatum sp. nov. is thecate, non‐photosynthetic, bilaterally flattened and somewhat elliptical in lateral view. The cell is 33–41 μm long and 23–30 μm deep. Several striae are present on the hypotheca. The plate formula is 3′, 6″, 6c, 5s?, 5″′, 1″″. Thecadinium yashimaense sp. nov. is bilaterally flattened, photosynthetic and elliptical in ventral view. The cell is 44–65 μm long and 23–36 μm wide. The thecal surface is smooth with small pores. he cingulum forms a steep left–handed spiral. The plate formula is Po, 3′, la, 6″, 5c, 4s, 5″′, 1″′. Thecadinium arenarium sp. nov. is somewhat wedge‐shaped in ventral view, photosynthetic with brownish chloroplasts and almost rounded in cross section. The cingulum forms a steep left‐handed spiral. The cell measures 35–41 μm in length and 25–30 μm in width. The thecal surface is weakly reticulated with small pores. The hypotheca is conical. The plate formula is Po, 3′, la, 6″, 5c, 4s, 5″′, 1″″.     

Heterocapsa psammophila sp. nov. (Peridiniales, Dinophyceae), a new sand-dwelling marine dinoflagellate

A new armored dinoflagellate species, Heterocapsa psammophila Tamura, Iwataki et Horiguchi sp. nov. is described from Kenmin‐no‐hama beach, Hiroshima, Japan using light and electron microscopy. This dinoflagellate possesses the typical thecal plate arrangement of the genus Heterocapsa, Po, cp, 5′, 3a, 7′′, 6c, 5s, 5′′′, 2′′′′; and the 3‐D body scales of Heterocapsa on the plasma membrane. The cell shape is ovoidal. The spherical nucleus and the pyrenoid are situated in the hypotheca and the epitheca, respectively. The ultrastructure of H. psammophila is typical of dinoflagellates and the pyrenoid is invaginated by cytoplasmic tubules. H. psammophila is distinguished from all other hitherto‐described Heterocapsa species by the cell shape, the relative position of the nucleus and pyrenoid and the structure of the body scale. The habitat and behavior of this new species in culture suggest that the organism is truly a sand‐dwelling species.     

Roscoffia minor sp. nov. (Peridiniales, Dinophyceae): A new, sand-dwelling, armored dinoflagellate from Hokkaido, Japan

A new, sand-dwelling, armored dinoflagellate, Roscoffia minor sp. nov., is described from Ishikari beach, Hokkaido, Japan. The dinoflagellate has been collected from sand samples taken both near the water's edge and further upshore (25 m from the water's edge at a depth of 1 m), indicating that it is a true sand-dwelling species. Roscoffia minor is heterotrophic and lacks both a chloroplast and an eye-spot. The cell consists of a flattened cap-shaped epitheca and a large hemispheroidal hypotheca, and it is quite different from cells of the typical armored dinoflagellates. The thecal plate formula is: Po, 3′, la, 5″, 3c, 3s, 5″, 1″″. Its distinct cell shape and the thecal plate arrangement indicate affinity to the monotypic genus Roscoffia. Roscoffia minor is distinguished from Roscoffia capitata, the type species, by its smaller size and the possession of a finger-like apical projection. The thecal arrangement of the epitheca is similar to those of the members of the family Podolampaceae, while the hypothecal arrangement is the same as that of members of the subfamily Diplopsalioideae (family Congruentidiaceae). The organism seems to be positioned somewhere intermediate between these two families, but the family to which this dinoflagellate should be affiliated could not be determined.     

Morphometric convergence among European sand gobies in freshwater (Gobiiformes: Gobionellidae)

The five genera of sand gobies inhabit the seas and freshwaters of Europe and western Asia and occupy habitats ranging from fully marine to exclusively freshwater. In this study, we use geometric morphometrics to quantify body shape among sand gobies, in order to investigate how shape has evolved and how it is related to habitat. We also compare body shape between preserved museum specimens and fresh specimens, to determine whether or not fixation and storage in ethanol introduce detectable bias. We confirm that the fixed specimens exhibit significant shape changes as compared to fresh specimens, and so, we perform the bulk of our analyses exclusively on fixed specimens. We find that Economidichthys, Orsinigobius, and Pomatoschistus occupy distinct regions of morphospace. Knipowitschia and Ninnigobius have intermediate forms that overlap with Pomatoschistus and Orsinigobius, but not Economidichthys. This pattern is also in rough accordance with their habitats: Pomatoschistus is fully marine, Economidichthys fully freshwater, and the others fresh with some brackish tolerance. We augment a recent phylogeny of sand gobies with data for P. quagga and interpret morphometric shape change on that tree. We then evaluate convergence in form among disparate lineages of freshwater species by constructing a phylomorphospace and applying pattern‐based (convevol) measures of convergence. We find that freshwater taxa occupy a mostly separate region of morphospace from marine taxa and exhibit significant convergence in form. Freshwater taxa are characterized by relatively larger heads and stockier bodies than their marine relatives, potentially due to a common pattern of heterochronic size reduction.     

A new potentially toxic Azadinium species (Dinophyceae) from the Mediterranean Sea,A. dexteroporum sp. nov.

A new photosynthetic planktonic marine dinoflagellate, Azadinium dexteroporum sp. nov., is described from the Gulf of Naples (South Tyrrhenian Sea, Mediterranean Sea). The plate formula of the species, Po, cp, X, 4′, 3a, 6″, 6C, 5?S, 6? and 2″″, is typical for this recently described genus. Azadinium dexteroporum is the smallest rep‐resentative of the genus (8.5 μm average length, 6.2 μm average width) and shares the presence of a small antapical spine with the type species A. spinosum and with A. polongum. However, it differs from all other Azadinium species for the markedly asymmetrical Po plate and the position of the ventral pore, which is located at the right posterior end of the Po plate. Another peculiarity of A. dexteroporum is the pronounced concavity of the second intercalary plate (2a), which appears collapsed with respect to the other plates. Phylogenetic analyses based on the large subunit 28S rDNA (D1/D2) and the internal transcribed spacer (ITS rDNA) support the attribution of A. dexteroporum to the genus Azadinium and its separation from the other known species. LC/MS‐TOF analysis shows that Azadinium dex‐teroporum produces azaspiracids in low amounts. Some of them have the same molecular weight as known compounds such as azaspiracid‐3 and ‐7 and Compound 3 from Amphidoma languida, as well as similar fragmentation patterns in some cases. This is the first finding of a species producing azapiracids in the Mediterranean Sea.     

The first description of the potentially toxic dinoflagellate, Alexandrium minutum in Hunts Bay, Kingston Harbour, Jamaica

The occurrence and morphology of the potentially toxic dinoflagellate species Alexandrium minutum found for the first time in Jamaica, were examined and described by light and scanning electron microscopy. Classical morphological examinations of whole cells, the thecal plate pattern of intact cells and more importantly the structure of individual thecal plates of squashed cells, were conducted in an attempt to positively identify the species. Characteristics such as a tear-drop shaped apical pore plate with a comma-shaped apical pore and no anterior attachment pore; a narrow sixth precingular plate; a narrow anterior sulcal plate longer than or approximately as long as it is wide; and a posterior sulcal plate wider than long, confirmed the Jamaican species as A. minutum. This dinoflagellate which produces potent neurotoxins responsible for paralytic shellfish poisoning (PSP) in humans in many parts of the World, as well as mass mortality of various marine flora and fauna, was identified in water samples collected during an extensive bloom of the species in the brackish to saline water body of Hunts Bay, an estuarine arm of Kingston Harbour, Jamaica in August 1994. The highest cell concentration was 4.6 × 10⁵ cells l⁻¹, a concentration which far exceeds acceptable concentrations (<10³ cells l⁻¹) of PSP-toxin producing A. minutum in several countries including: Spain and Denmark. No PSP human symptoms were reported during the bloom; however it was accompanied by a large kill of small pelagic fish extending across a third of the bay. Since then, smaller blooms of A. minutum have occurred with the most recent in February and April 2004. Hunts Bay is an important fishing, shrimping and to some extent oyster/mussel collection area and provides an important source of livelihood and food for many fishermen in nearby fishing communities as well as an important source of food for members of other communities. Although there are no known records of human illness due to PSP in Jamaica, the occurrence and blooming in Jamaican waters of this potentially toxic dinoflagellate, is great cause for concern.     

PROTOPERIDINIUM BELIZEANUM SP. NOV. (DINOPHYCEAE) FROM MANATEE CAY,BELIZE, CENTRAL AMERICA1

A new marine heterotrophic dinoflagellate species, Protoperidinium belizeanum sp. nov., from a coral reef‐mangrove pond was identified from scanning electron micrographs. Recognition of this new species was based on unique features of the thecal morphology, which included cell size and shape, presence of short and wide postcingular plates, sulcal architecture, antapical spines, and intricate thecal plate patterns of ridged hexagonal depressions. The thecal plate formula is as follows: Po, X, 4′, 3a, 7″, 4C (3+t), 6S, 5?, 2″″. Species association of P. be‐lizeanum sp. nov. within the genus Protoperidinium, its habitat, and associated dinoflagellates species are discussed.     

Amphidiniopsis uroensis sp. nov. and Amphidiniopsis pectinaria sp. nov. (Dinophyceae): Two new benthic dinoflage llates from Japan

Two new armoured, heterotrophic sand‐dwelling marine dinoflagellates, Amphidiniopsis uroensis Toriumi, Yoshimatsu et Dodge sp. nov. and Amphidiniopsis pectinaria Toriumi, Yoshimatsu et Dodge sp. nov. were collected from Japanese sandy beaches, and their morphological features observed by light microscopy and scanning electron microscopy (SEM). The cell size of A. uroensis is 28–31 μm in length and 23–28 μm in width. The plate formula is Po 3′, 3a, 6″, 3c, 4s (+1 acc.), 5″′, 2″″. The thecal surface is ornamented with small processes, pores and spines, however, the surface of plate 2a is smooth. The epitheca possesses a narrow ridge that is extended along on the suture between 1′ and 3′. Plate 1″ connects with the right sulcal (Sd) and right sulcal accessory (Sda) plates, so the cingulum is incomplete. A nucleus is situated in the central part of the cell. There are a few small spines at the antapex. There are no stigma or chloroplasts. Amphidiniopsis pectinaria cells are 33–40 urn in length and 29–35 μm in width. The plate formula is Po 4′, 3a, 7″, 3c, 4s (+1 acc.), 5″′, 2″″. Plate 1″ connects directly with Sd and Sda plates, so the cingulum is incomplete. The thecal surface is ornamented with small processes, spines and pores. The epitheca is provided with a narrow ridge that is extended along on the suture between plates 1′, 4′ and 7″. The ornamentation on the antapical plates is unique. It is arranged in 10 straight rows on the hypotheca; each row has a strong spine at its posterior end. In addition, there is a long spine at the antapex. There are no stigma or chloroplasts. A nucleus is located in the central part of the cell.