STARRIA ZIMBABWEËNSIS (CYANOPHYCEAE) GEN. NOV. ET SP. NOV.: A FILAMENT TRIRADIATE IN TRANVERSE SECTION1

A new filamentous bluegreen alga Starria zimbabweënsis gen. nov. et sp. nov. isolated from a soil sample collected near Zimbabwe, Southern Rhodesia, has a unique triradiate morphology. In transverse section each narrow cell possesses three arm-like projections, separated by 120° and in which pigment is concentrated. Filaments may be straight or twisted and various clonable biradiate forms have originated in cultures initiated from the triradiate type. Cell ultra-structure is typical of the Oscillatoriaceae except that 70 nm pit-like pores occur throughout the L-II layer of the longitudinal walls. Wall structure of deviant forms is identical to that of the triradiate “wild type.” The organism is assigned to the Oscillatoriaceae rather than to the Gomontiellaceae or to a new family.     

DESCRIPTION OF A NEW GENUS OF PFIESTERIA‐LIKE DINOFLAGELLATE,LUCIELLA GEN. NOV. (DINOPHYCEAE), INCLUDING TWO NEW SPECIES: LUCIELLA MASANENSIS SP. NOV. AND LUCIELLA ATLANTIS SP. NOV.1

A new genus of Pfiesteria‐like heterotrophic dinoflagellate, Luciella gen. nov., and two new species, Luciella masanensis sp. nov. and Luciella atlantis sp. nov., are described. These species commonly occur with other small (<20 μm) heterotrophic and mixotrophic dinoflagellates in estuaries from Florida to Maryland and the southern coast of Korea, suggesting a possible global distribution. An SEM analysis indicates that members of the genus Luciella have the enhanced Kofoidian plate formula of Po, cp, X, 4′, 2a, 6″, 6c, PC, 5+s, 5?, 0p, and 2″″. The two four‐sided anterior intercalary plates are diamond shaped. The genus Luciella differs from the other genera in the Pfiesteriaceae by a least one plate in the plate tabulation and in the configuration of the two anterior intercalary plates. An SSU rDNA phylogenetic analysis confirmed the genus as monophyletic and distinct from the other genera in the Pfiesteriaceae. The morphology of Luciella masanensis closely resembles Pfiesteria piscicida Steid. et J. M. Burkh. and other Pfiesteria‐like dinoflagellates in size and shape, making it easily misidentified using LM. Luciella atlantis, in contrast, has a more distinctive morphology. It can be distinguished from L. masanensis and other Pfiesteria‐like organisms by a larger cell size, a more conical‐shaped epitheca and hypotheca, larger rhombic‐shaped intercalary plates, and an asymmetrical hypotheca. The genus Luciella is assigned to the order Peridiniales and the family Pfiesteriaceae based on plate tabulation, plate pattern, general morphology, and phylogenetic analysis.     

PARMALES (CHRYSOPHYCEAE) FROM THE GULF OF TEHUANTEPEC,MEXICO, INCLUDING THE DESCRIPTION OF A NEW SPECIES,TETRAPARMA INSECTA SP. NOV., AND A PROPOSAL TO THE TAXONOMY OF THE GROUP1

There are few studies dedicated to species of the Order Parmales all over the world. All 12 taxa described are part of the marine ultraplankton (less than 5 μm). Analysis of filtered samples from the Gulf of Tehuantepec yielded specimens of two taxa of the group. One is a new species, belonging to the genus Tetraparma. Tetraparma insecta sp. nov. is solitary and spherical (2.8–3.8 μm diameter), and all plates lack ornamentations or knobs, the walls are smooth, and only the plate junctions are seen. The shield plates are convex and show a conspicuous rim, some of them with an indentation. This species shows superficial similarities with Tetraparma pelagica, the other species described of the genus, and is very similar to siliceous forms, previously found, with no formal name. The other species is the taxon Triparma laevis form mexicana (Kosman) stat. nov., earlier described for Mexican waters, which has an irregular ala, the shield plates have knobs at the center, the triradiate plates show a “Y”‐shaped keel, and the walls of plates and ala show minute granules. Tetraparma insecta was distributed widely in the study area and was relatively abundant, reaching a density of 4 × 10⁴·L^?1, with an evident preference for subsurface waters (10–20 m depth), whereas T. laevis form mexicana was rare and scarce. Both species seem to be restricted to tropical–subtropical waters. We discuss the taxonomy of Parmales, especially concerning the category of subspecies within the group. Parmales is a widespread group in cold and tropical waters.     

ITOPSIDEMA,A NEW GENUS OF THE OSMUNDACEAE FROM THE TRIASSIC OF ARIZONA

Daugherty , Lyman H. (San Jose State College, San Jose, Calif.) Itopsidema, a new genus of the Osmundaceae from the Triassic of Arizona. Amer. Jour. Bot 47(9): 771–777. Illus. 1960.—Itopsidema vancleavei, a new genus and species of the family Osmundaceae, is described. The specimen consists of several segments of an arborescent stem obtained from the Upper Triassic of the Petrified Forest National Monument near Holbrook, Arizona. The surfaces on 2 of the segments are covered by adventitious roots and the remaining segments are covered by leaf bases. The fronds are spirally arranged and have an 8/21 phyllotaxy. The cortex of the stem, which contains numerous leaf traces and adventitious roots, consists of parenchyma with cell walls of medium thickness. The leaf traces are oblong to crescent-shaped in the inner cortex and horseshoe-shaped in the outer cortex. The base of the petiole contains a single, large vascular bundle and is covered by multicelled, glandular spines. The adventitious roots originate on the abaxial side of the leaf traces in the region of the inner cortex. The center of the stem is occupied by an ectophloic, mesarch siphonostele without leaf gaps. The pith is composed of firm-walled parenchyma cells which have isolated tracheids with reticulate pitting scattered among them. These tracheids are so rare the pith cannot be considered a “mixed pith.” The relationship and morphological significance of Itopsidema with respect to other members of the Osmundaceae are briefly discussed.     

LESSARDIA ELONGATA GEN. ET SP. NOV. (DINOFLAGELLATA,PERIDINIALES, PODOLAMPACEAE) AND THE TAXONOMIC POSITION OF THE GENUS ROSCOFFIA1

We investigate an organism that closely resembles the nonphotosynthetic dinoflagellate “Gymnodinium elongatum” Hope 1954 using EM and molecular methods. Cells are 20–35 μm long, 10 μm wide, biconical, transparent, and have a faint broad girdle. Thecal plates are thin but present (plate formula Po Pi CP 3′ 1–2A 5″ 3C 6S 4? 3″″). With the exception of one feature, the presence of three antapical plates, the amphiesmal arrangement of this species is consistent with that of the order Peridiniales, family Podolampaceae; it is not at all consistent with the characteristics of the genus Gymnodinium. On the basis of these ultrastructural findings, we establish a new genus, Lessardia, and a new species, Lessardia elongata Saldarriaga et Taylor. Molecular phylogenetic analyses were performed using the small subunit rRNA genes of L. elongata as well as Roscoffia capitata, a member of a genus of uncertain systematic position that has been postulated to be related to the Podolampaceae. These analyses place Lessardia and Roscoffia as sister lineages within the so‐called GPP complex. Thecal plate arrangements led us to expand the family Podolampaceae to include the genus Lessardia and, in combination with new molecular results, to propose a close relationship between the Podolampaceae and Roscoffia. Within this lineage, Lessardia and Roscoffia appear to have retained a number of ancestral characters: Roscoffia still has a well‐developed cingulum, a feature absent in all members of the Podolampaceae, and Lessardia has more than one antapical plate, a character reminiscent of some members of the family Protoperidiniaceae.     

ACROSYMPHYTON FIRMUM SP. NOV. (RHODOPHYTA,CRYPTONEMIALES), A NEW SUBTIDAL RED ALGA FROM NEW ZEALAND; DEVELOPMENTAL MORPHOLOGY AND DISTRIBUTION OF THE GAMETOPHYTE1

Acrosymphyton firmum sp. nov., is described from the northeastern coast of North 1., New Zealand. Gametophytes are spring–summer annuals which grow subtidally on cobbles. Thalli are uniaxial; each axial cell bears a whorl of four indeterminate and one determinate branchlets. Indeterminate branchlets are alternately arranged giving the thallus a distichous and feather-like appearance. Numerous corticating rhizoidal filaments are produced from the periaxial and lower whorl branchlet cells. These rhizoids entwine and obscure the main axis as the thallus develops until in the mature plant the axes have a firm consistency and lubricous texture. The carpogonial branch bearing short lateral filaments and auxiliary cell branch with terminal auxiliary cell place this new species in the genus Acrosymphyton Sjöstedt. Of the three described species in the genus, A. firmum is most similar to A. taylori. This is the first report of the genus Acrosymphyton and the only confirmed report of the family Dumontiaceae in New Zealand waters.     

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.     

THE POLYMORPHIC DIATOM PHAEODACTYLUM TRICORNUTUM: ULTRASTRUCTURE OF ITS MORPHOTYPES1,2

The ultrastructure of the oval, fusiform and triradiate morphotypes of Phaeodactylum tricornutum Bohlin is described. The organization and structure of the cytoplasmic organelles is similar in all three morphotypes, except that the vacuoles occupy the extra volume created by the arms of the fusiform and triradiate cells. The frustule in fusiform and triradiate cells is organic; in the oval type it may be organic or one of the valves may have a silica frustule surrounded by an organic wall. In all cells, the organic cell wall has up to 10 silica bands (13 nm wide) embedded in its surface in the girdle region, lacks girdle bands, and has an outer corrugated cell wall layer, except in the girdle region. Cell division, organic wall formation and silica deposition are described in detail. Four types of oval cells are also described. The relation to other diatoms is discussed.     

THE RECLASSIFICATION OF PFIESTERIA SHUMWAYAE (DINOPHYCEAE): PSEUDOPFIESTERIA,GEN. NOV.1

Pfiesteria shumwayae Glasgow et Burkholder is assigned to a new genus Pseudopfiesteria gen. nov. Plate tabulation differences between Pfiesteria and Pseudopfiesteria gen. nov. as well as a maximum likelihood phylogenetic analysis based on rDNA sequence data warrant creation of this new genus. The Kofoidian thecal plate formula for the new genus is Po, cp, X, 4′, 1a, 6′′, 6c, PC, 5+s, 5′′′, 0p, 2′′′′. In addition to having six precingular plates, P. shumwayae comb. nov. also has a distinctive diamond or rectangular‐shaped anterior intercalary plate. Both Pfiesteria and Pseudopfiesteria gen. nov. are reassigned to the order Peridiniales based on an apical pore complex (APC) with a canal (X) plate that contacts a symmetrical 1′, four to five sulcal plates, and the conservative hypothecal tabulation of 5′′′, 0p, and 2′′′′. These morphological characters and the life histories of Pfiesteria and Pseudopfiesteria are consistent with placement of both genera in the Peridiniales. Based on the plate tabulations for P. shumwayae, P. piscicida, and the closely related “cryptoperidiniopsoid” and “lucy” groups, the family Pfiesteriaceae is amended to include species with the following tabulation: 4‐5′, 0‐2a, 5‐6′′, 6c, PC, 5+s, 5′′′, 0p, and 2′′′′ as well as an APC containing a pore plate (Po), a closing plate (cp), and an X plate; the tabulation is expanded to increase the number of sulcal plates and to include a new plate, the peduncle cover (PC) plate. Members of the family have typical dinoflagellate life cycles characterized by a biflagellated free‐living motile stage, a varying number of cyst stages, and the absence of multiple amoeboid stages.     

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.     

曲靖西冲鱼(Xichonolepis qujingensis)化石的新材料及对其某些形态特征的讨论

<正> 曲靖西冲鱼(Xichonolepis qujingensis P'an et Wang)是1978年潘江、王士涛二同志为胴甲鱼建立的一个属种。化石产在云南曲靖翠峰山徐家冲与西冲之间中泥盆统海口组的下部。建立这一属种的标本有躯甲上一件骨片的内、外印模(原作者认为系前中背片)和若干属于头甲和胸鳍甲某些散落骨片的内、外印模,材料不多,保存也不甚完好。本文系对曲靖西冲鱼形态特征的补充记述,标本是刘玉海、王俊卿和笔者等自1962年以来陆续在滇东中泥盆统采获的。最初,在武定赵家庄后山的泥灰岩层与刘氏滇鱼     

云南武定节甲类的新材料

文中描述了采自云南武定中泥盆统一新的属种Yinostius maior gen.et sp.nov.属于短胸节甲类Heterosteidae科,这类化石在我国系初次发现。     

江西崇义地区上泥盆统节甲类(Arthrodira)的新材料

我国泥盆系鱼化石非常丰富,尤其是下、中泥盆统。但是,上泥盆统鱼化石发现尚少,而且主要是胴甲类化石,节甲类化石则很少发现。潘江（１９６２）在对斯行健已记述的一植物化石 Ｃｈａｎｇｙａｎｏｐｈｙｔｏｎ ｈｏｐｅｉｅｎｓｉｓ Ｓｚｅ重新进行观察时认为,该化石应属于盾皮鱼类,并将其归人瓣甲类 Ｍａｃｒｏｐｔｅｔａｌｉｃｈｔｈｙｉｄａｅ（？）,化石仅包括前腹侧片和胸棘。 Ｄｅｎｉｓｏｎ（１９７８）根据潘江的文章和插图则认为, Ｃｈａｎｇｙａｎｏｐｈｙｔｏｎ ｈｕｐｅｉｅｎｓｉｓ属于原始节甲类或者瓣甲类。王念忠等…     

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.     

Ontogenetic analysis of siliceous cell wall formation in Triparma laevis f. inornata (Parmales,Stramenopiles)

Triparma laevis f. inornata is a unicellular alga belonging to the Bolidophyceae, which is most closely related to diatoms. Like diatoms, T. laevis f. inornata has a siliceous cell wall. The cell wall of T. laevis f. inornata consists of four round plates (three shields and one ventral plate) and one dorsal and three girdle plates. But, unlike diatoms, T. laevis f. inornata cells can grow when concentrations of silica are depleted. We took advantage of this ability, using TEM to study the ontogeny of the siliceous plate, pattern center formation, and development. Two types of pattern centers (annulus and sternum) were observed in the early and middle stage of plate formation. During their formation, the annuli were initially crescent‐shaped but eventually their ends fused to make a ring. Only outward silica deposition of the branching ribs occurred on the growing annulus until it became a ring, resulting in an unfilled circle inside the annulus. The pattern center of the shield plate was always an annulus, but in ventral plates both annulus and sternum were observed. The annuli and sterna in T. laevis f. inornata round plates were very similar to the annuli and sterna in diatom valves. These results suggested that the round plates of Parmales are homologous to diatom valves. This information on the plate ontogeny of T. laevis f. inornata provides new insights into the evolution of the siliceous cell wall in the Parmales and diatoms.     

Effects of Silicon-Limitation on Growth and Morphology of Triparma laevis NIES-2565 (Parmales,Heterokontophyta)

The order Parmales (Heterokontophyta) is a group of small-sized unicellular marine phytoplankton, which is distributed widely from tropical to polar waters. The cells of Parmales are surrounded by a distinctive cell wall, which consists of several siliceous plates fitting edge to edge. Phylogenetic and morphological analyses suggest that Parmales is one of the key organisms for elucidating the evolutionary origin of Bacillariophyceae (diatoms), the most successful heterokontophyta. The effects of silicon-limitation on growth and morphogenesis of plates were studied using a strain of Triparma laevis NIES-2565, which was cultured for the first time in artificial sea water. The cells of T. laevis were surrounded by eight plates when grown with sufficient silicon. However, plate formation became incomplete when cells were cultured in a medium containing low silicate (ca. <10 µM). Cells finally lost almost all plates in a medium containing silicate concentrations lower than ca. 1 µM. However, silicon-limitation did not affect growth rate; cells continued to divide without changing their growth rate, even after all plates were lost. Loss of plates was reversible; when cells without plates were transferred to a medium containing sufficient silicate, regeneration of shield and ventral plates was followed by the formation of girdle and triradiate plates. The results indicate that the response to silicon-limitation of T. laevis is different from that of diatoms, where cell division becomes inhibited under such conditions.     

中国东北原尾虫一新属一新种(原尾纲,蚖科)

报道了采自我国东北地区辽宁省兴城市原尾虫1新属辽宁妧属Liaoxientulus gen.nov.及新种兴城辽宁妧Liaoxientulus xingchengensis sp.nov.和该属的1个未定名种Liaoxientulus sp.,新属属于蚖科屠妧亚科.新属与采自东北黑龙江省的屠妧亚科伊春蚖属Yichunentulus Yin,1980形态最为相近,其与后者主要差别在于下唇须和前跗内侧感觉器b′不同,伊春妧属下唇须有1根膨大的感觉器和4根刚毛,前跗内侧感觉器b′缺如;新属下唇须退化,其上感觉器缺如,刚毛只有3根,但是前跗内侧感觉器b′存在.新属现有2个种,均为此次新发现,其中1个种为新种Liaoxientulus xingchengensis sp.nov.,另外1个种为未定名种Liaoxientulus sp..新种正模1只和副模1只以及该属另1未定名种标本保存在中国科学院东北地理与农业生态研究所,新种另2只副模保存在上海植物生理生态所昆虫博物馆.     

Cytokinesis in flowering plants: more than one way to divide a cell

Several different cytokinetic mechanisms operate in flowering plants. During 'conventional' somatic cytokinesis, the mitotic spindle remnants give rise to a phragmoplast that serves as a framework for the assembly of the cell plate. Cell plates fuse with the parental plasma membrane at specific cortical sites previously defined by the preprophase band of microtubules. In nuclear endosperms, meiocytes, and gametophytic cells, cytokinesis occurs without preprophase bands. The position of the new cell walls is determined instead by interacting arrays of microtubules that radiate from the nuclear envelope surfaces. The nuclear cytoplasmic domains defined by these microtubule arrays demarcate the boundaries of the future cells. Recent studies have provided new insights into the ultrastructural similarities and dissimilarities between conventional and non-conventional cytokinesis. Numerous proteins have also been localized to cytokinesis-related cytoskeletal arrays and cell plates but the functions of most of them have yet to be elucidated.     

Arabidopsis dynamin-like protein DRP1A: a null mutant with widespread defects in endocytosis, cellulose synthesis, cytokinesis, and cell expansion

Dynamin-related proteins are large GTPases that deform and cause fission of membranes. The DRP1 family of Arabidopsis thaliana has five members of which DRP1A, DRP1C, and DRP1E are widely expressed. Likely functions of DRP1A were identified by studying rsw9, a null mutant of the Columbia ecotype that grows continuously but with altered morphology. Mutant roots and hypocotyls are short and swollen, features plausibly originating in their cellulose-deficient walls. The reduction in cellulose is specific since non-cellulosic polysaccharides in rsw9 have more arabinose, xylose, and galactose than those in wild type. Cell plates in rsw9 roots lack DRP1A but still retain DRP1E. Abnormally placed and often incomplete cell walls are preceded by abnormally curved cell plates. Notwithstanding these division abnormalities, roots and stems add new cells at wild-type rates and organ elongation slows because rsw9 cells do not grow as long as wild-type cells. Absence of DRP1A reduces endocytotic uptake of FM4-64 into the cytoplasm of root cells and the hypersensitivity of elongation and radial swelling in rsw9 to the trafficking inhibitor monensin suggests that impaired endocytosis may contribute to the development of shorter fatter roots, probably by reducing cellulose synthesis.