ALEXANDRIUM TAMUTUM SP. NOV. (DINOPHYCEAE): A NEW NONTOXIC SPECIES IN THE GENUS ALEXANDRIUM1

A new species of the dinoflagellate genus Alexandrium, A. tamutum sp. nov., is described based on the results of morphological and phylogenetic studies carried out on strains isolated from two sites in the Mediterranean Sea: the Gulf of Trieste (northern Adriatic Sea) and the Gulf of Naples (central Tyrrhenian Sea). Vegetative cells were examined in LM and SEM, and resting cysts were obtained by crossing strains of opposite mating type. Alexandrium tamutum is a small‐sized species, resembling A. minutum in its small size, the rounded‐elliptical shape and the morphology of its cyst. The main diagnostic character of the new species is a relatively wide and large sixth precingular plate (6″), whereas that of A. minutum is much narrower and smaller. Contrary to A. minutum, A. tamutum strains did not produce paralytic shellfish poisoning toxins. Phylogenies inferred from the nuclear small subunit rDNA and the D1/D2 domains of the large subunit nuclear rDNA of five strains of A. tamutum and numerous strains of other Alexandrium species showed that A. tamutum strains clustered in a well‐supported clade, distinct from A. minutum.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

PORPHYRA REDIVIVA SP. NOV. (RHODOPHYTA): A NEW SPECIES FROM NORTHEAST PACIFIC SALT MARSHES1

A new species, Porphyra rediviva (Bangiales, Rhodophyta), is described from the northeast Pacific based on morphological, cytological, reproductive, ecological, and molecular characters. This species occurs at high intertidal levels in salt marshes along the coasts of Washington, Oregon, and northern California and exhibits a growth optimum at reduced salinity. It is further distinguished by a distinct demarcation between male and female sectors of the gametophytic thalli of epilithic specimens. The species is found most commonly in the drift or trapped in Salicornia beds, but these detached blades never have been found with sporangia or gametangia. Molecular analyses using restriction fragment length polymorphism patterns of polymerase chain reaction–amplified ribosomal DNA (rDNA) show that this salt marsh Porphyra is conspecific throughout its range and is distinct from other Pacific Porphyra species with similar reproductive patterns. Based on molecular data, P. rediviva is related most closely to P. purpurea from the North Atlantic. Fixed rDNA polymorphisms between the two taxa, however, support ecological and cytological evidence that they should be considered different species.     

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.     

CACHONINA ILLDEFINA SP. NOV. (DINOPHYCEAE): CHLOROPLAST TUBULES AND DEGENERATION OF THE PYRENOID1

A new species of the dinoflagellate genus Cachonina, C. illdefina sp. nov., was isolated from a red tide off El Capitan State Park, Santa Barbara County, California, in October 1973. The organism is light yellowgreen in color with deeply incised girdle and sulcal grooves. Electron microscopy of the organism, revealed a typical dinokaryotic nucleus. The chloroplasts of the organism are connected, and often contain microtubule-like elements, 25 nm diam. The pyrenoids are characterized as excluding chloroplast thylakoids and ribosomes, although containing an amorphous matrix and numerous tubular invaginations from the cytoplasm. The pyrenoids become detached from the chloroplasts and degenerate into small vesicles. C. illdefina is not bioluminescent.     

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.     

PYCNOCOCCUS PROVASOLII GEN. ET SP. NOV., A COCCOID PRASINOXANTHIN-CONTAINING PHYTOPLANKTER FROM THE WESTERN NORTH ATLANTIC AND GULF OF MEXICO1

The new genus Pycnococcus Guillard is based on several clones from the western North Atlantic and Gulf of Mexico. The type and only described species, Pycnococcus provasolii Guillard, sp. nov., is typified by clone Ω48-23 from the North Atlantic. Cells of Pycnococcus provasolii are solitary, spherical, 1.5–4.0 μm in diameter, have a resistant cell wall lacking sporopollenin, and have the ultrastructural characteristics of green algae. With the light microscope they are scarcely distinguishable from cells of other coccoid planktonic organisms. In pigmentation P. provasolii resembles Micromonas pusilla, Mantoniella squamata, and Mamiella gilva in having chl a, much chl b, Mg 2,4-divinylphaeoporphyrin a₅ monomethyl ester (presumably), and prasinoxanthin as a major xanthophyll. The pyrenoid of P. provasolii has a cytoplasmic channel, which is unique among species closely related to it. Flagellates, occurring rarely in culture, are similar to but distinguishable from known Pedinomonas species by size and shape. Pycnococcus provasolii is referred to the new family Pycnococcaceae Guillard, in the order Mamiellales of the class Micromonadophyceae (Chlorophyta). Clones of Pycnococcus provasolii are oceanic in nutritional characteristics, require only vitamin B₁₂ in culture, and are well adapted to growth under blue or blue-violet light of low intensity.     

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.     

THE ULTRASTRUCTURE OF PYRAMIMONAS PSEUDOPARKEAE SP. NOV. (PRASINOPHYCEAE) FROM SOUTH AFRICA1

The ultrastructure of Pyramimonas pseudoparkeae sp. nov., a member of the class Prasinophyceae occurring in tidal pools along the east, south and west coast of South Africa, is described. The cell surface is covered by three distinctive body scales whilst the flagellar surfaces possess four types of scales. The structure of these scales is described. P. pseudoparkeae resembles Pyramimonas parkeae Norris and Pearson but differs in the structure of the type 2 body scale. The symmetry and ultrastructure of the cell are described with special attention given to the flagellar apparatus. Preliminary information on the life cycle of this species is presented. This new species is compared with other closely related members of the genus Pyramimonas.     

COMPARATIVE DEVELOPMENT OF THE RED ALGAL PARASITES BOSTRYCHIOCOLAX AUSTRALIS GEN. ET SP. NOV. AND DAWSONIOCOLAX BOSTRYCHIAE (CHOREOCOLACACEAE,RHODOPHYTA)1

The development of two red algal parasites was examined in laboratory culture. The red algal parasite Bostrychiocolax australis gen. et sp. nov., from Australia, originally misidentified as Dawsoniocolax bostrychiae (Joly et Yamaguishi-Tomita) Joly et Yamaguishi-Tomita, completes its life history in 6 weeks on its host Bostrychia radicans (Montagne) Montagne. Initially the spores divide to form a small lenticular cell, and then a germ tube grows from the opposite pole. Upon contact with the host cuticle, the germ tube penetrates the host cell wall. The tip of the germ tube expands, and the spore cytoplasm moves into this expanded tip. The expanded germ tube tip becomes the first endophytic cell from which a parasite cell is cut off that fuses with a host tier cell. The nuclei of this infected host cell enlarge. As parasite development continues, other host-parasite cell fusions are formed, transferring more parasite nuclei into host cells. The erumpent colorless multicellular parasite develops externally on the host, and reproductive structures are visible within 2 weeks. Tetrasporangia are superficial and cruciately or tetra-hedrally divided. Spermatia are formed in clusters. The carpogonial branches are four-celled, and the carpogonium fuses directly with the auxiliary (support) cell. The mature carposporophyte has a large central fusion cell and sympodially branched gonimoblast filaments. Early stages of development differ markedly in Dawsoniocolax bostrychiae from Brazil. Upon contact with the host, the spore undergoes a nearly equal division, and a germ tube elongates from the more basal of the two spore cells, penetrates the host cell wall, and fuses with a host tier cell. Subsequent development involves enlargement of the original spore body and division to form a multicellular cushion, from which descending rhizoidal filaments form that fuse with underlying host cells. This radically different development is in marked contrast to the final reproductive morphology, which is similar to B. australis and has lead to taxonomic confusion between these two entities. The different spore germination patterns and early germ-ling development of B. australis and D. bostrychiae warrant the formation of a new genus for the Australian parasite.     

湖北宜昌奥陶纪大湾组的三叶虫新种 Ovalocephalus eoprimitivus sp.nov.

本文记述湖北宜昌地区奥陶纪大湾组下部的一个三叶虫新种Ovalocephalus eoprimitivus sp.nov.,主要特征是头鞍缺失前颈环横沟。Ovalocephalus Koroleva为泛冈瓦纳的标志分子,在中国奥陶系分布极为广泛。这一新种的时代为弗洛期—大坪期,系该属目前所知地层层位最低的分子。     

MARIPELTA ATLANTICA SP. NOV. (RHODOPHYTA,RHODYMENIALES) A NEW DEEP-WATER ALGA FROM FLORIDA1

A red alga with a cylindrical stipe bearing a single deciduous blade was collected in deep water off the east coast of Florida. It is described as Maripelta atlantica sp. nov., differing from M. rotata (Dawson) Dawson (the type of the genus, from deep water off California and Baja California) chiefly by having an annular tetrasporangial nemathecium on the lower surface of the blade rather than scattered nemathecia on the upper surface. Both species are vegetatively and reproductively distinct from M. thivyae Dawson, which is transferred to Halichrysis. New information is given regarding the reproduction and distribution of M. rotata.