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.     

SYMBIODINIUM NATANS SP. NOV.: A “FREE‐LIVING” DINOFLAGELLATE FROM TENERIFE (NORTHEAST‐ATLANTIC OCEAN)1

We examined a free‐living Symbiodinium species by light and electron microscopy and nuclear‐encoded partial LSU rDNA sequence data. The strain was isolated from a net plankton sample collected in near‐shore waters at Tenerife, the Canary Islands. Comparing the thecal plate tabulation of the free‐living Symbiodinium to that of S. microadriaticum Freud., it became clear that a few but significant differences could be noted. The isolate possessed two rather than three antapical plates, six rather than seven to eight postcingular plates, and finally four rather than five apical plates. The electron microscopic study also revealed the presence of an eyespot with brick‐shaped contents in the sulcal region and a narrow anterior plate with small knob‐like structures. Bayesian analysis revealed the free‐living Symbiodinium to be a member of the earliest diverging clade A. However, it did not group within subclade A_I (=temperate A) or any other subclades within clade A. Rather, it occupied an isolated position, and this was also supported by sequence divergence estimates. On the basis of comparative analysis of the thecal plate tabulation and the inferred phylogeny, we propose that the Symbiodinium isolate from Tenerife is a new species (viz. S. natans). To elucidate further the species diversity of Symbiodinium, particularly those inhabiting coral reefs, we suggest combining morphological features of the thecal plate pattern with gene sequence data. Indeed, future examination of motile stages originating from symbiont isolates will demonstrate if this proves a feasible way to identify and characterize additional species of Symbiodinium and thus match ribotypes or clusters of ribotypes to species.     

MORPHOLOGY AND MOLECULAR PHYLOGENY OF A NEW MARINE SAND‐DWELLING PROROCENTRUM SPECIES,P. TSAWWASSENENSE (DINOPHYCEAE,PROROCENTRALES), FROM BRITISH COLUMBIA,CANADA1

A new marine benthic, sand‐dwelling Prorocentrum species from the temperate region of the Pacific coast of British Columbia, Canada, is described using LM and EM and molecular phylogenetic analyses. The cells have a broad oval shape, 40.0–55.0 μm long and 30.0–47.5 μm wide, and a wide U‐shaped periflagellar area on the right thecal plate. The left thecal plate consists of a straighter apical outline in the form of a raised ridge. Five to six delicate apical spines in the center of the periflagellar area are present. The nucleus is located in the posterior region of the cell, and a conspicuous pusule is located in the anterior region of the cell. The cells have golden‐brown chloroplasts with a compound, intrachloroplast pyrenoid that lacks a starch sheath. The thecal plates are smooth with round pores of two different sizes. The larger pores are arranged in a specific pattern of radial rows that are evenly spaced around the plate periphery and of irregular rows (or double rows) that form an incomplete “V” at the apical end of the plates. Large pores are absent in the center of the left and right thecal plates. The intercalary band is striated transversely and also has faint horizontal striations. Trichocysts and two types of mucocysts are present. The molecular phylogenetic position of Prorocentrum tsawwassenense sp. nov. was inferred using SSU rDNA sequences. This new species branched with high support in a Prorocentrum clade containing both benthic and planktonic species.     

Further use of fluorochromes in the cytochemical characterization of phytoplankton

Summary The rapid, specific effects of 25 fluorochromes at low concentration and physiological conditions of pH and temperature were investigated on live cells of five phytoplankton species (Prorocentrum micans, Amphidinium carterae, Dunaliella tertiolecta, Chlamydomonas moewusii andFragilaria crotonensis). They allowed the identification of cellular components such as the plasma membrane, endoplasmic reticulum, Golgi apparatus, thecal plates, nucleus, mitochondria, trichocysts, vacuoles/lysosomes, polyphosphate and starch granules, lipid bodies and hydrolytic enzymes. Morphological alterations of some of these constituents were examined in cells at different metabolic states. It was found that the thickness ofProrocentrum thecal plates increases during cell development while surface pores appear to be formed in the early stages of thecal formation. The number and size of mitochondria varies among cells at different stages of growth. The number of trichocysts, the size of vacuoles and the quantity of polyphosphates, starch or lipid inclusions increases in nitrogen-depleted cells. Photodegradation and photoenhancement phenomena are described. Some important factors helping to avoid quenching and some applications of the fluorochroming technique are presented.     

THECAL ULTRASTRUCTURE OF THE TOXIC MARINE DINOFLAGELLATE GONYAULAX CATENELLA1

The toxic marine dinoflagellate Gonyaulax catenella Whedon & Kofoid was studied with scanning and transmission electron microscopy to describe the thecal morphology and to accurately define the taxonomic characters of the species. The closing platelet which lies in a U-shaped apical pore was revealed to be disassociable from a partly obscured apical platelet. Two previously unreported sulcal plates were charaterized and described. The entire complement of thecal plates numbered 33.     

Morphology and Molecular Phylogeny of a New Marine,Sand-dwelling Dinoflagellate Genus,Pachena (Dinophyceae), with Descriptions of Three New Species

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.     

MORPHOLOGY AND ECOLOGY OF THE MARINE BENTHIC DINOFLAGELLATE SCRIPPSIELLA SUBSALSA (DINOPHYCEAE)1

The thecal surface morphology of Scrippsiella subsalsa (Ostenfeld) Steidinger et Balech was examined using the scanning electron microscope. This species is distinguished by a number of morphological characteristics. Apical plate 1′ is wide, asymmetric, and pentagonal, and it ends at the anterior margin of the cingulum. Intercalary plates 2a and 3a are separated by apical plate 3′. The apical pore complex includes a large P_o plate with a raised dome at the center and a deep canal plate with thickened margins at plates 2′, 3′, and 4′. The intercalary bands are wide and deeply striated. The cingulum is deep, formed by six cingular plates; its surface is transversely striated and aligned with a row of minute pores. The cingular list continues around postcingular plate 1′” to form a sulcal list. The sulcal list is a flexible ribbon with a rounded tip that protrudes posteriorly, partially covering the sulcal plates. The hypotheca is lobed, and the antapical plates are irregularly shaped and wide in antapical view. The thecal surface is vermiculate to reticulate. A comparison in morphology and ecology is presented between S. subsalsa and other known Scrippsiella species.     

Alexandrium diversaporum sp. nov., a new non-saxitoxin producing species: Phylogeny,morphology and sxtA genes

Species of the PST producing planktonic marine dinoflagellate genus Alexandrium have been intensively scrutinised, and it is therefore surprising that new taxa can still be found. Here we report a new species, Alexandrium diversaporum nov. sp., isolated from spherical cysts found at two sites in Tasmania, Australia. This species differs in its morphology from all previously reported Alexandrium species, possessing a unique combination of morphological features: the presence of 2 size classes of thecal pores on the cell surface, a medium cell size, the size and shape of the 6″, 1′, 2⁗ and Sp plates, the lack of a ventral pore, a lack of anterior and posterior connecting pores, and a lack of chain formation. We determined the relationship of the two strains to other species of Alexandrium based on an alignment of concatenated SSU-ITS1, 5.8S, ITS2 and partial LSU ribosomal RNA sequences, and found A. diversaporum to be a sister group to Alexandrium leei with high support. A. leei shares several morphological features, including the relative size and shapes of the 6″, 1′, 2⁗ and Sp plates and the fact that some strains of A. leei have two size classes of thecal pores. We examined A. diversaporum strains for saxitoxin production and found them to be non-toxic. The species lacked sequences for the domain A4 of sxtA, as has been previously found for non-saxitoxin producing species of Alexandrium.     

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.     

ULTRASTRUCTURE OF THE DINOFLAGELLATE PERIDINIUM CINCTUM F. OVOPLANUM. II. LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS ON FERTILIZATION

Fertilization in Peridinium cinctum f. ovoplamtm has been investigated at both the light and electron microscopic levels. Gamete formation occurs when vegetative cells are placed into nitrogen deficient media. The majority of gametes observed possess thin thecal plates; however, some are naked. Gametes have few chloroplasts as compared to vegetative cells, numerous membrane bounded storage bodies, many starch grains, and chromosomes which appear slightly unwound. Gamete fusion is observed to peak 7–10 days after inoculation into nitrogen deficient media. Fusion occurs in an area of the sulcus devoid of reticulate thecal plates at or adjacent to the flagellar pores. A fertilization tube is formed and proceeds to widen along the sulcus. Karyogamy occurs within the fertilization tube before plasmogamy is completed. The resulting planozygote is a two walled structure containing two longitudinal flagella. It enlarges over a 2-week period giving rise to the hypnozygote.     

The genus Glochidinium gen. nov., with two species: G. penardiforme comb. nov. and G. platygaster sp. nov. (Peridiniaceae)

Glochidiniumgen. nov., a ncw genus of Peridiniaceae based on Peridinium penardiforme Lindemann, is herewith erected. Its plate formula is: Po+X+4′+6′′+3C+4S+5′′′+2′′′′ Main diagnostic characters of this new genus are the presence of only 3 cingular plates (it lacks the transitionalone), the third cingular contacting the anterior sulcal plate, and an unusual sulcus holding a small triangular posterior sulcal plate. The thecal morphology and structure of two freshwater planktic species of the genus are described on the basis of LM and SEM observations. G. penardiforme comb. nov. is an infrequent species, albeit widely distributed world-wide. It has been recorded under the names of Peridinium, Glenodinium and Peridiniopsis. Peculiar features in the tabulation of the furrows and of the surface sculpture show that the species does not fit any of the known genera, for which reason the new genus Glochidinium is established. G. platygaster sp. nov., the second species included in the genus, differs from the former by its elongated body, the regular pentagonal shape of its large first apical plate, an equally large sulcal anterior plate, and well developed sculpture, chiefly on the antapical plates. Glochidinium penardiforme and G. platygaster were found in some reservoirs from central and northern Argentina. G. penardiforme was also found in several Argentine rivers and ponds.     

Morphology and molecular phylogeny of the benthic dinoflagellates (Dinophyceae,Peridiniales) Amphidiniopsis crumena n. sp. and Amphidiniopsis nileribanjensis n. sp.

Amphidiniopsis is a benthic, heterotrophic and thecate dinoflagellate genus that has a smaller epitheca and larger hypotheca. The genus contains 24 described species, but is considered to be polyphyletic based on morphological characters and molecular phylogenetics. In this study, two new species were discovered from two distant sampling localities, Amphidiniopsis crumena sp. nov. from Japan, and Amphidiniopsis nileribanjensis sp. nov., from Australia. These species have a uniquely shaped, additional second postcingular plate. Both species are dorsoventrally flattened, an apical hook is present, and have six postcingular plates. The plate formula is: APC 4′ 3a 7″ ?C 4?S 6″′ 2″″. The cells of these species were examined with LM and SEM, and molecular phylogenic analyses were performed using 18S and 28S rDNA. These species are distinguished by the presence of spines on the hypotheca and touching of the sixth postcingular plate and the anterior sulcal plate. Their shape and disposition of several thecal plates also differ. Molecular phylogenetic analyses showed that the two new species formed a monophyletic clade and did not belong to any morphogroup proposed by previous studies. Considering the morphological features and the molecular phylogenetic results, a new morphogroup is proposed, Amphidiniopsis morphogroup VI (‘crumena group’).     

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.     

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.     

The ontogeny of cinctans (stem‐group Echinodermata) as revealed by a new genus,GraciaCystis, from the middle Cambrian of Spain

Abstract:  A new cinctan echinoderm, Graciacystis ambigua gen. et sp. nov. from Cambrian Series 3 rocks of Spain, is described based on more than 100 articulated specimens that range from 6 to 14.5 mm in thecal length. This material shows that Graciacystis ambigua, while plastic in thecal shape, is highly conservative in its thecal construction, with a fixed number of marginal plates and very limited addition of plates in the stele and ventral membrane through ontogeny. Ventral swellings on marginal elements are absent from the smallest specimens and become gradually more marked during growth. A cladistic analysis shows Graciacystis to be a basal cinctan, more derived than Sotocinctus and the Trochocystitidae and as sister group to a large clade formed by Sucocystidae + Gyrocystidae. The determinate growth pattern seen in Graciacystis seems to be the general pattern for all cinctans.     

Amphidiniella sedentaria gen. et sp. nov. (Dinophyceae), a new sand-dwelling dinoflagellate from Japan

A new sand-dwelling dinoflagellate is described from Sesoko Beach, Okinawa Island, subtropical Japan and its micromorphology is studied by means of light and electron microscopy. The cell consists of a small epitheca and a large hypothecs superficially resembling members of the unarmored genus Amphidinium. The cell is dorso-ventrally flattened and possesses a single chloroplast with a large conspicuous pyrenoid. Transmission electron microscopy revealed that the dinoflagellate possesses typical dinoflagellate cellular organization. Scanning electron microscopy demonstrated that the organism is thecate and the thecal plate arrangement is Po, 4′, 1a, 7″, 5c, 4s, 6″′, 2″″. Most of the characteristics suggest gonyaulacalean affinity of the new species. These are the presence of ventral pore, lack of canal plate, direct contact between the sulcal anterior plate and the flagellar pore, possession of six postcingular plates and asymmetrical arrangement of the antapical plates. Affinity to existing families of the order Gonyaulacales has not been determined. Based on the unique cell shape, thecal plate arrangement and the presence of ventral pore, a new genus, Amphidiniella, is established for this organism and the species is named A. sedentaria Horiguchi gen. et sp. nov.     

Morphology and biomechanical implications of isolated discocystinid plates (Edrioasteroidea, Echinodermata) from the Carboniferous of North America

Detailed examination of isolated thecal plates belonging to three discocystinid edrioasteroids, Spiraclavus nacoensis Sumrall, Hypsiclavus kinsleyi Sumrall, and Giganticlavus bennisoni Sumrall and Bowsher, reveals striking similarity in morphology among these species. Stereom observed in the ambulacral floor plates indicates that ligamentous connective tissue opened the ambulacral cover plates and muscle tissue closed them. The ambulacral floor plates are interpreted as rigid supports for the oral surface with the interambulacral areas acting as flexible integuments of plates. The aboral surface is interpreted as flexible and highly contractile. All discocystinid thecal openings are consistent in morphology with adaptations for thecal pressurization. Extension and contraction of the theca was accomplished by pumping water in and out of an inflatable sac associated with the periproctial opening. The pedunculate zone is interpreted as passively expanding and contracting by relaxing of mutable collagenous tissue and stiffening when the theca was in the desired position. All of these features illustrate that discocystinid edrioasteroids have highly–evolved morphology and function.     

Morphology and phylogenetic interpretation of a new Cambrian edrioasteroid (Echinodermata) from Spain

Abstract: The edrioasteroid, Aragocystites belli gen. nov. sp. nov. from the middle Cambrian Murero Formation of Spain, is described based on a small number of very well‐preserved specimens. Important anatomical characteristics include star‐shaped and pseudoclavate theca, rare or absent epispires, well‐developed interradially positioned oral plates and several unorganized cover plates associated with each widely exposed flooring plate. A phylogenetic analysis including several Cambro–Ordovician species shows it is more derived than Stromatocystites and Totiglobus but is a sister group to a clade comprising Cambraster and Edriodiscus. Ontogenetic observations based on juveniles of 5 mm in diameter suggest that this species changed thecal shape markedly during growth. A. belli gen. nov. sp. nov. probably lived in quiet environments where it attached directly to the sea floor on stabilized substrates.     

Arctotheca calendula (L.) Levyns: An emerging invasive species in Italy

Abstract

Prevention and early detection are considered to be the most effective means of managing non-native invasive species that have serious ecological and economic impacts. Consequently, the study of those taxa that are still in an early stage of invasion but are highly likely to spread and to have a significant adverse impact in future is becoming an increasingly important issue in both the research on and management of invasive species. In Italy, one such species is Arctotheca calendula (L.) Levyns, a herbaceous plant of the Asteraceae family that is native to South Africa. Here, we present an overview of current knowledge on the distribution and potential impacts of this species in Italy, and we outline some features that are crucial to understanding and preventing its invasive spread.