PROROCENTRUM BELIZEANUM,PROROCENTRUM ELEGANS,AND PROROCENTRUM CARIBBAEUM,THREE NEW BENTHIC SPECIES (DINOPHYCEAE) FROM A MANGROVE ISLAND,TWIN CAYS,BELIZE1

Three new benthic dinoflagellate species, Prorocentrum belizeanum, Prorocentrum elegans, and Prorocentrum caribbaeum, from mangrove floating detritus are described from scanning electron micrographs. Species were identified based on shape, size, surface micromorphology, ornamentation of thecal plates, and architecture of the periflagellar area and intercalary band. Cells of P. belizeanum are round to slightly oval with a cell size of 55–60 μm long and 50–55 μm wide. Areolae are round and numerous (853–1024 per valve) and range from 0.66 to 0.83 μm in size. The periflagellar area of P. belizeanum is a broad V-shaped depression; it accommodates a flagellar and an auxiliary pore and a flared, curved apical collar. The intercalary band of P. belizeanum is horizontally striated. Prorocentrum elegans is a small species 15–20 μm long and 10–14 μm wide, with an ovate cell shape. The thecal surface is smooth. Two sizes of valve pores were recognized: large, round pores (20–22 per valve) arranged in a distinct pattern and smaller pores situated in an array along the intercalary band. The periflagellar area is V-shaped; it accommodates an uneven sized flagellar pore, an auxiliary pore, and an angled protuberant flagellar plate. The intercalary band is transversely striated. It is a bloom-forming species. Prorocentrum caribbaeum cells are heart-shaped with a rounded anterior end and a pointed posterior end. Cells range from 40 to 45 μm long and 30 to 35 μm wide. Thecal surface has two different-sized pores: large, round pores (145–203 per valve) arranged perpendicularly from the posterior margins, and small, round pores unevenly distributed on the thecal surface. The periflagellar area is ornate. It is V-shaped with a curved apical collar located next to the auxiliary pore; a smaller protuberant apical plate is adjacent to the flagellar pore. The intercalary band is transversely striated and sinuous. Cells are active swimmers.     

THREE NEW BENTHIC SPECIES OF PROROCENTRUM (DINOPHYCEAE) FROM BELIZE: P. NORRISIANUM SP. NOV., P. TROPICALIS SP. NOV., and P. RETICULATUM SP. NOV.1

Three new benthic, photosynthetic dinoflagellate species, Prorocentrum norrisianum, Prorocentrum tropicalis, and Prorocentrum reticulatum, from floating detritus and coral rubble of Central America are described from scanning electron micrographs. Species were identified based on shape, size, surface micromorphology, thecal plate ornamentation, and architecture of the periflagellar area and intercalary band. Cells of P. norrisianum are ovate with a cell size of 20–25 μm long and 13–16 μm wide. The theca is delicate, its surface smooth, pores species specific with 95 to 105 pores per valve. Pores are round with a diameter of about 0.1 μm. The periflagellar area is V-shaped, located on the right valve in a shallow depression. It has no ornamentation. The flagellar and auxiliary pores are unequal in size. The intercalary band is smooth. Prorocentrum tropicalis cells are ovoid, 50–55 μm long and 40–45 μm wide in valve view with maximum width behind the middle region, narrow at the anterior end. The periflagellar area, situated in the right valve, is a V-shaped wide triangle with a deeply indented depression; the left valve exhibits a flat ridge. The periflagellar area is unornamented, and the flagellar and auxiliary pores are unequal in size. The valve surface is rugose with evenly distributed valve poroids. Each poroid appears to have a small dome in the center. The intercalary band is rimlike around the cell margin, granulated, and horizontally striated. Prorocentrum reticulatum cells are oblong in valve view; cells are 55–60 μm long and 40–45 μm wide. Thecal surface is reticulated; it is composed of a labyrinth of ridges with alternating depressions that vary in size and shape. Each depression has a narrow, oblong-kidney-shaped opening about 0.6 μm long. The periflagellar area is a deep, V-shaped triangle. The right valve of P. reticulatum is excavated, and contains a large flagellar pore and a smaller auxiliary pore surrounded by a narrow apical collar. The left valve margin exhibits a curved flat ridge. The intercalary band is smooth.     

THREE NEW BENTHIC SPECIES OF PROROCENTRUM (DINOPHYCEAE) FROM CARRIE BOW CAY,BELIZE: P. SABULOSUM SP. NOV., P. SCULPTILE SP. NOV., AND P. ARENARIUM SP. NOV.1

Three new benthic, sand-dwelling dinqflagellate species, Prorocentrum sabulosum, Prorocentrum scuptile, and Prorocentrum arenarium, from coral rubble are described from scanning electron micrographs. Species were identified based on shape, size, surface micromorphology, ornamentation of thecal plates, and architecture of the periflagellar area and intercalary band. Cells of P. sabulosum are oval with a cell size of 48–50 μm long and 41–48 μm wide. The areolae are round to oval and numerous (332–450 per valve) and range from 1 to 1.6 μm in size. The periflagellar area of P. sabulosum bears a wide V-shaped depression with a flat ridge and lacks ornamentation; it accommodates six pores: one large flagellar pore, an adjacent smaller auxiliary pore, and four pores of unknown function. The flagellar and auxiliary pores are surrounded by a narrow apical collar. The intercalary band of P. sabulosum is smooth. Prorocentrum sculptile cells are broadly oval, 32–37 nm long, and 30–32 μm wide in valve view with a deep-sculptured apical area. The valves are smooth and are marked with shallow depressions (856–975 per valve). Some of these depressions have a small round opening (0.13 μm in diameter). The periflagellar area is V-shaped with a deeply indented depression; it accommodates the two flagella and a thin angled apical plate. The intercalary band is smooth. Prorocentrum arenarium cells are nearly round in valve view 30–32 μm in diameter. Thecal surface is smooth with scattered kidney-shaped valve poroids (65–73 per valve) and marginal poroids (50–57 per valve). Length and width of poroids are 0.62 μm and 0.36 μm, respectively. The periflagellar area is an unornamented, broad triangle into which a large flagellar pore and a smaller auxiliary pore are fitted. Both flagella, longitudinal and transverse, protrude from the flagellar pore. The intercalary band is smooth. The presence of a peduncle-like structure (2–3 μm long) in P. arenarium was observed situated in the flagellar pore.     

PROROCENTRUM LEVIS,A NEW BENTHIC SPECIES (DINOPHYCEAE) FROM A MANGROVE ISLAND,TWIN CAYS,BELIZE1

As part of a long‐term study of benthic dinoflagellates from the Belizean barrier reef system, we report a new species: Prorocentrum levis M. A. Faust, Kibler, Vandersea, P. A. Tester et Litaker sp. nov. P. levis cells are oval in valve view and range in size from 40 to 44 μm long and 37 to 40 μm wide. Each valve surface is smooth, with 221–238 valve pores and 99–130 marginal pores. These pores are uniformly small and range in diameter from 0.13 to 0.19 μm. Asexual reproduction in P. levis is atypical, occurring within a hyaline envelope, and produces long branching chains of adherent cells. A phylogenetic analysis of SSU rDNA indicated that of the Prorocentrum species sequenced so far, P. levis was most closely related to P. concavum. P. levis produces okadaic acid and dinophysis toxin‐2 (DTX2). Further, SEM observations and SSU rDNA sequence for P. belizeanum M. A. Faust, which was isolated at the same time, are also presented.     

A FURTHER SEM STUDY OF MARINE BENTHIC DINOFLAGELLATES FROM A MANGROVE ISLAND,TWIN CAYS,BELIZE, INCLUDING PLAGIODINIUM BELIZEANUM GEN. ET SP. NOV.1

This study indicates that bilaterally flattened, armored, benthic dinoflagellates are more diverse in morphology than previously known. A new species, Plagiodinium belizeanum Faust et Balech gen. et. sp. nov., is described in floating detritus from Twin Cays, Belize, mangrove habitats. Plagiodinium belizeanum cells are small, with dimensions of 26.5–30.5 μm in length, 20–24.5 μm in width, and 6.5–8.5 μm in depth. Cells are oblong and bilaterally compressed with a posteriorly located, spherical nucleus, many chloroplasts, and spherical starch granules. The epitheca descends ventrally, is cap-shaped, and is composed of five plates and a very small platelet provisionally named P₀ situated in the center. The epitheca is narrowly oval in apical view with a pointed truncated ventral side and a rounded dorsal side. The cingulum is composed of five plates. The hypotheca is constructed of five posteriorly elongated postcingular plates and one antapical plate. The sulcus is very short and narrow, comprised of five very small plates. The thecal plate arrangement of P. belizeanum is P₀, 5′, O″, 5C, 5″′, 1″″, 5S. No lists are present. Thecal plates have a smooth surface with small and irregularly scattered pores. The intercalary band is smooth on outer cell surface and broadly striated on its inner surface. We conclude that P. belizeanum represents a new, benthic, peridinioid, armored genus, Plagiodinium gen. nov. The taxonomic position of P. belizeanum sp. nov. is compared to related sand-dwelling and bilaterally flattened benthic dinoflagellates.     

ALEXANDRIUM SATOANUM SP. NOV. (DINOPHYCEAE) FROM MATOYA BAY,CENTRAL JAPAN1

The gonyaulacoid dinofiagellate Alexandrium satoanum Yuki et Fukuyo sp. nov. is described from Matoya Bay, Pacific coast of central Japan. The species is distinctive in its conical epitheca with almost straight sides and dorsal concavity of the hypotheca. The plate formula is Po, pc, 4′, 6″, 6c, 10s, 5″″, and 2″″, including two accessory plates inside the sulcus. The apical pore plate is triangular and possesses an anterior attachment pore at the right margin. The first apical plate does not make contact with the apical pore plate and lacks a ventral pore. A posterior attachment pore lies at the center of the posterior sulcal plate. In Matoya Bay, vegetative cells occur as solitary cells or sometimes in pairs during late spring and early summer in low concentrations. In connection with this study, the following new combination is proposed: Alexandrium pseudogonyaulax (Biecheler) Horiguchi ex Yuki et Fukuyo comb. nov.     

MORPHOLOGY AND MOLECULAR ANALYSES OF THREE TOXIC SPECIES OF GAMBIERDISCUS (DINOPHYCEAE): G. PACIFICUS, SP. NOV., G. AUSTRALES, SP. NOV., AND G. POLYNESIENSIS, SP. NOV.

Three new dinoflagellate species, Gambierdiscus polynesiensis, sp. nov., Gambierdiscus australes, sp. nov., and Gambierdiscus pacificus, sp. nov., are described from scanning electron micrographs. The morphology of the three new Gambierdiscus species is compared with the type species Gambierdiscus toxicus Adachi et Fukuyo 1979, and two other species: Gambierdiscus belizeanus Faust 1995 and Gambierdiscus yasumotoi Holmes 1998. The plate formula is: Po, 3′, 7", 6C, 8S, 5‴, 1p, 2". Culture extracts of these three new species displayed both ciguatoxin- and maitotoxin-like toxicities. The following morphological characteristics differentiated each species. 1) Cells of G. polynesiensis are 68–85 μm long and 64–75 μm wide, and the cell’s surface is smooth. They are identified by a large triangular apical pore plate (Po), a narrow fish-hook opening surrounded by 38 round pores, and a large, broad posterior intercalary plate (1p) wedged between narrow postcingular plates 2‴ and 4‴. Plate 1p occupies 60% of the width of the hypotheca. 2) Cells of G. australes also have a smooth surface and are 76–93 μm long and 65–85 μm wide in dorsoventral depth. They are identified by the broad ellipsoid apical pore plate (Po) surrounded by 31 round pores and a long and narrow 1p plate wedged between postcingular plates 2‴ and 4‴. Plate 1p occupies 30% of the width of the hypotheca. 3) Cells of G. pacificus are 67–77 μm long and 60–76 μm wide in dorsoventral depth, and its surface is smooth. They are identified by the four-sided apical pore plate (Po) surrounded by 30 round pores. A short narrow 1p plate is wedged between the wide postcingular plates 2‴ and 4‴. Plate 1p occupies 20% of the width of the hypotheca. These three newly described species were also characterized by isozyme electrophoresis and DNA sequencing of the D8–D10 region of their large subunit (LSU) rRNA genes. The consistency between species designations based on SEM microscopy and classification inferred from biochemical and genetic heterogeneities was examined among seven isolates of Gambierdiscus. Their classification into four morphospecies was not consistent with groupings inferred from isozyme patterns. Three molecular types could be distinguished based on the comparison of their LSU rDNA sequences. Although G. toxicus TUR was found to be more closely related to G. pacificus, sp. nov. than to other G. toxicus strains, the molecular classification was able to discriminate G. polynesiensis, sp. nov. and G. australes, sp. nov. from G. toxicus. These results suggest the usefulness of the D8–D10 portion of the Gambierdiscus LSU rDNA as a valuable taxonomic marker.     

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.     

SURFACE MORPHOLOGY OF THE MARINE DINOFLAGELLATE SINOPHYSIS MICROCEPHALUS (DINOPHYCEAE) FROM A MANGROVE ISLAND. TWIN CAYS. BELIZE1

Sinophysis microcephalus Nie and Wang 1944 is a nonphotosynthetic, tropical, benthic. dinophysoid dinoflagellate. I isolated it from floating detritus on a subtropical mangrove island. Twin Cays. Beleze, Central America, and describe its micromorphology from light and scanning electron micrographs. Cells of S. microcephalus are circular to subcircular and compressed laterally with a cell size of 42-44 μm long and 33–35 μm wide and with a length /width ratio of 1.25–1.28. Areolae are numerous, 368–550 per valve, ranging in size from 0.75 to 2.0 μm. Pores are oblong and deeper at the valve's center and pentagonal-shaped at the plate margin. The well-defined cingulum is narrow and deeply incised with a smooth surface. The epitheca is small, moderately convex, and divided into two large, highly ornate, asymmetrical plate: the left and right epitheca I plates. The left epithecal plate bears two slightly curved, upright anterior projections located dorsally adjacent to the epithecal list, a relatively large opening, and three smaller openings compressed against the sagittal suture. The right plate contains a wide megacytic zone with two parallel ridges, a fairly large oblong opical pore in ventral position adjacent to the cingulum, and eight areolae each with a round, uniform-sized pore opening. There are two long and narrow sulcal lists, gently convex with a smooth edge without structure or ribs. The left sulcal list has an ear-shaped labe, a form of a primitive dinophysoid list. The megacytic zone is smooth and expands unevenly during cell division. The epitheca and sulcus distinguishes S. microcephalus from all examined Dinophysis.     

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.     

AMPHIDINIUM CRYOPHILUM SP. NOV. (DINOPHYCEAE) A NEW FRESHWATER DINOFLAGELLATE. I. SPECIES DESCRIPTION USING LIGHT AND SCANNING ELECTRON MICROSCOPY1

Amphidinium cryophilum sp. nov. was found in the fall of 1979 in a small pond near Madison, Wisconsin. During the ensuing winter, it became the dominant phytoplankter. Cell numbers remained high despite a thick layer of ice and snow. After the ice melted in the spring the organism disappeared from plankton samples. A successful culture of A. cryophilum was established only when isolates were incubated at 5–7° C. It is compared with two morphologically similar species, A. amphidinioides (Geitler) Schiller and Gymnodinium inversum Nygaard. Amphidinium cryophilum is distinguished from the former by its pigmentation (golden-yellow vs. blue-green), the location of the cingulum, and its lack of an eyespot. It differs from the latter in cell shape, the route of the sulcus and position of the nucleus.     

MORPHOLOGIC DETAILS OF SIX BENTHIC SPECIES OF PROROCENTRUM (PYRROPHYTA) FROM A MANGROVE ISLAND,TWIN CAYS,BELIZE, INCLUDING TWO NEW SPECIES1

Two new dinoflagellate species, Prorocentrum hoffmannianum and Prorocentrum ruetzlerianum, and four known species, Prorocentrum emarginatum Fukuyo 1981, Prorocentrum mesicanum Tafall 1942, Prorocentrum concavum Fukuyo 1981, and Prorocentrum lima (Ehr.) Dodge 1975, from floating detritus and sediments in a subtropical mangrove island, Twin Cays, Belize, Central America are described from scanning electron micrographs. Differences in the following characters of surface micromorphology separated the species: ornamentation of thecal plates (shape, size, and number of valve pores and areolae) and the architecture of the periflagellar area and intercalary band.     

MORPHOLOGY AND SYSTEMATICS OF SCIUROTHAMNION STEGENGAE GEN. ET SP. NOV. (CERAMIACEAE,RHODOPHYTA) FROM THE INDO‐PACIFIC1

A new ceramiaceous alga, Sciurothamnion stegengae De Clerck et Kraft, gen. et sp. nov., is described from the western Indian Ocean and the Philippines. Sciurothamnion appears related to the tribe Callithamnieae on the basis of the position and composition of its procarps and by the majority of post‐fertilization events. It differs, however, from all current members of the tribe by the presence of two periaxial cells bearing determinate laterals per axial cell. Additionally, unlike any present representative of the subfamily Callithamnioideae, no intercalary foot cell is formed after diploidization of the paired auxiliary cells. The genus is characterized by a terminal foot cell (“disposal cell”), which segregates the haploid nuclei of the diploidized auxiliary cell from the diploid zygote nucleus. The nature of three types of foot cells reported in the Ceramiaceae (intercalary foot cells containing only haploid nuclei, intercalary foot cells containing haploid nuclei and a diploid nucleus, and terminal foot cells containing only haploid nuclei) is discussed.     

PHYLOGENETIC ANALYSIS OF NINE SPECIES OF PROROCENTRUM (DINOPHYCEAE) INFERRED FROM 18S RIBOSOMAL DNA SEQUENCES, MORPHOLOGICAL COMPARISONS, AND DESCRIPTION OF PROROCENTRUM PANAMENSIS, SP. NOV.

Sequences of 18S rRNA genes were obtained from eight species of Prorocentrum Ehrenberg: P. minimum (Pavillard) Schiller, P. mexicanum Osorio Tafall, P. emarginatum Fukuyo, P. lima (Ehrenberg) Dodge, P. arenarium Faust, P. maculosum Faust, P. concavum Fukuyo, and P. panamensis, sp. nov. Prorocentrum panamensis is a new species of tropical dinoflagellate isolated from a benthic coral reef on the Pacific coast of Panama and described here using scanning electron microscopy. Cells are heart shaped, 46–52 μm long and 43–46 μm wide. The valve surfaces are areolate except in the central area. Pores of 0.15 μm in diameter are scattered in areolae, mainly around the periphery of the cell. The right valve has a specific ovoid depression with numerous appressed pores; we named this structure the sieve-like depression. The periflagellar area is nearly ovoid, located in a shallow depression, and almost equally set into both valves. It is unornamented (no apical expansion) but has numerous depressions in platelets. The flagellar and auxiliary pores are different in size and shape. The intercalary band is transversally striated. Phylogenetic relationships of gonyaulacoid, peridinioid, gymnodinioid, and prorocentroid dinoflagellates were inferred from complete 18S rDNA sequences. Two distinct phylogenetic analyses are presented for armored and unarmored Dinophyceae in an attempt to make the phylogenetic relationships between these different kinds of organisms clearer. The Prorocentrales appear to have a common origin, although two groups of Prorocentrum spp. are apparent. The first group includes benthic, symmetrical species (P. lima, P. arenarium, P. maculosum, and P. concavum). The second group contains planktonic and bentho-planktonic species (P. micans Ehrenberg, P. minimum, P. mexicanum, and P. panamensis sp. nov.). Genetic distances between species within these two groups were high; however, the divergence between the two groups seems to have occurred late in dinoflagellate evolution. In addition, the bentho-planktonic P. emarginatum appeared distantly related to both groups; however,its 18S rDNA sequence shares specific nucleotide substitutions with the two groups, suggesting an older origin of this species compared to the others. A morphological interpretation of this phylogenetic analysis is made on the basis of the specific structure of the periflagellar area. Finally, genetic data and morphological observations support the hypothesis that the genus Prorocentrum is rather heterogeneous; several species could be considered to constitute distinct genera.     

POLARELLA GLACIALIS, GEN. NOV., SP. NOV. (DINOPHYCEAE): SUESSIACEAE ARE STILL ALIVE!

The culture CCMP 1383, obtained from sea-ice brine collected in McMurdo Sound (Ross Sea, Antarctica), is a small gymnodinioid dinoflagellate. This species is very abundant in the upper land-fast sea ice, where it can both grow and overwinter as a spiny encysted stage. The motile vegetative stage and the cyst produced in the culture were studied by scanning electron microscopy (SEM) and transmission electron micrscopy (TEM). The amphiesma of the vegetative cells is constituted by thin vesicles that are organized into nine latitudinal series of plates: three in the epitheca, two in the cingulum, and four in the hypotheca. The same tabulation is reflected in the cyst wall by acicular processes arising from the center of paraplates, with the exception of the paracingulum, in which acicular processess are absent. On the basis of the peculiar plate pattern of this dinoflagellate, we establish the new genus Polarella and the new species Polarella glacialis (family Suessiaceae, order Suessiales). This species has a remarkable similarity with fossil Suessiaceae cysts dating back to the Triassic and Jurassic and represents, up to now, the only extant member of the subfamily Suessiaceae. Phylogenetic analysis based on the small-subunit ribosomal RNA gene confirmed the placement of this species in the order Suessiales and its close relationship with the genus Symbiodinium Freudenthal.     

缅甸北部克钦白垩纪中期琥珀中的蜡蝉化石一新属新种: Ayaimatum trilobatum gen. et sp. nov.(半翅目: 蜡蝉总科: 拟蛛蜡蝉科)

根据缅甸北部克钦地区产出的白垩纪中期琥珀中保存的蜡蝉,建立了1新属1新种——三瓣残缺蜡蝉(Ayaimatum trilobatum gen. et sp. nov.),该新属新种属于白垩纪的拟蛛蜡蝉科(Mimarachnidae)。本文对拟蛛蜡蝉科的属种记录进行了综述,同时探讨了这一灭绝科属种的多样性和形态分异。     

HALOSTYLODINIUM ARENARIUM, GEN ET SP. NOV. (DINOPHYCEAE), A COCCOID SAND-DWELLING DINOFLAGELLATE FROM SUBTROPICAL JAPAN

A new genus and species of marine coccoid dinoflagellate from subtropical Japan, Halostylodinium arenarium Horiguchi et Yoshizawa-Ebata, gen. et sp. nov., is described. The dominant stage of the dinoflagellate is a nonmotile ovoidal to spheroidal cell with a distinct stalk. The stalk consists of an upper thick tubule, a lower thin tubule, and a discoidal holdfast. The dinoflagellate possesses a yellowish-brown chloroplast with multiple lobes radiating from a central pyrenoid. It reproduces by the formation of two motile cells, which swim for a short period and then transform directly into the stalked nonmotile cell. The stalk is produced during transformation from the apical stalk complex present in the apex of the motile cell. The apical stalk complex consists of a double-folded apical pore plate and doughnut-shaped holdfast-building material. The ultrastructure of the apical stalk complex is compared with those of Bysmatrum arenicola and Stylodinium littorale. Halostylodinium arenarium possesses delicate thecal plates, and the thecal plate formula is Po, 5', 2a, 7", 7c, 6s, 5"', 1p, 2"". A phylogenetic study based on the 18S ribosomal RNA gene did not show any clear affinities between this organism and any species included in the analysis.     

CRYPTOPERIDINIOPSIS BRODYI GEN. ET SP. NOV. (DINOPHYCEAE), A SMALL LIGHTLY ARMORED DINOFLAGELLATE IN THE PFIESTERIACEAE1

A new genus and species of heterotrophic dinoflagellate, Cryptoperidiniopsis brodyi gen. et sp. nov., are described. This new species commonly occurs in estuaries from Florida to Maryland, and is often associated with Pfiesteria piscicida Steidinger et Burkholder, Pseudopfiesteria shumwayae (Glasgow et Burkholder) Litaker et al., and Karlodinium veneficum (Ballantine) J. Larsen, as well as other small (<20 μm) heterotrophic and mixotrophic dinoflagellates. C. brodyi gen. et sp. nov. feeds myzocytotically on pigmented microalgae and other microorganisms. The genus and species have the enhanced Kofoidian plate formula of Po, cp, X, 5′, 0a, 6″, 6c, PC, 5+s, 5″′, 0p, and 2″″ and are assigned to the order Peridiniales and the family Pfiesteriaceae. Because the Pfiesteriaceae comprise small species and are difficult to differentiate by light microscopy, C. brodyi gen. et sp. nov. can be easily misidentified.