TAXONOMY AND MOLECULAR PHYLOGENY OF THE RED ALGAL GENUS LENORMANDIA (RHODOMELACEAE,CERAMIALES)1

The genus Lenormandia Sonder is currently composed of nine species from Australia and New Zealand. Some of these are well known, but others are rare and ill defined. Material of all nine species has been examined and found to fall into three discrete morphological groups forming highly supported clades on analysis of 18S rDNA sequences. The first group contains four Australian‐endemic species and includes the type species L. spectabilis Sonder. Plants have a cleft apex that is not inrolled, a distinctive rhombic surface areolation pattern caused by a one‐ to two‐layered medulla of interlocking cells, lack pseudopericentral cells, and produce their reproductive structures on the blade surfaces. The type species of the genus Lenormandiopsis, L. latifolia (Harvey et Greville) Papenfuss, was found to belong to this group and is thus returned to Lenormandia where it was originally placed. Species falling into the other two groups are removed to new genera that are being described separately. One extremely rare species of Lenormandia from southwestern Australia is transferred to the delesseriacean genus Phitymophora.     

PHYLOGENY OF EUGLENOPHYCEAE BASED ON SMALL SUBUNIT rDNA SEQUENCES: TAXONOMIC IMPLICATIONS1

Small subunit rDNA sequences of 42 taxa belonging to 10 genera were used to infer phylogenetic relationships among euglenoids. Members of the phototrophic genera Euglena, Phacus, Lepocinclis, Colacium, Trachelomonas, and Strombomonas plus the osmotrophs Astasia longa, Khawkinea quartana, and Hyalophacus ocellatus were included. Six major clades were found in most trees using multiple methods. The utility of Bayesian analyses in resolving these clades is demonstrated. The genus Phacus was polyphyletic with taxa sorting into two main clades. The two clades correlated with overall morphology and corresponded in large part to the previously defined sections, Pleur‐ aspis Pochmann and Proterophacus Pochmann. Euglena was also polyphyletic and split into two clades. In Bayesian analyses species with less plastic pellicles and small disk‐like chloroplasts diverged at the base of the tree. They grouped into a single clade which included the two Lepocinclis spp., which also are rigid and bear similar chloroplasts. The metabolic Euglena species with larger plastids bearing pyrenoids and paramylon caps arose near the top of the tree. The loricates Strombomonas and Trachelomonas formed two well‐ supported, but paraphyletic, clades. The strong support for the individual clades confirmed the value of using lorica features as taxonomic criteria. The separation of the osmotrophic species A. longa, K. quartana, and H. ocellatus into different clades suggested that the loss of the photosynthetic ability has occurred multiple times.     

ORIGINS AND AFFINITIES OF THE FILAMENTOUS GREEN ALGAL ORDERS CHAETOPHORALES AND OEDOGONIALES BASED ON 18S rRNA GENE SEQUENCES

The order Chaetophorales includes filamentous green algae whose taxonomic relationships to other chlorophycean orders is uncertain. Chaetophoralean taxa include filamentous species which are both branched and unbranched. Ultrastructural studies of zoospores have revealed similar flagellar apparatuses in a number of genera, including Uronema, Stigeoclonium, and Fritschiella, suggesting a close phylogenetic relationship among these taxa. The order Oedogoniales represents a second group of branched and unbranched filamentous green algae whose relationships to other chlorophycean orders also has been unclear. A possible close relationship between the Chaetophorales and Oedogoniales has been suggested. Using DNA sequences from the small-subunit ribosomal RNA gene (SSU rRNA) of several members of each order, we have examined the monophyly of the Chaetophorales and Oedogoniales, as well as the nature of their relationship to other chlorophycean orders. Our results show that chaetophoralean and oedogonialean taxa form separate monophyletic groups. Results also suggest that the two orders are not closely related to each other.     

DISCRIMINATIVE POWER OF NUCLEAR rDNA SEQUENCES FOR THE DNA TAXONOMY OF THE DINOFLAGELLATE GENUS PERIDINIUM (DINOPHYCEAE)1

The genus Peridinium Ehrenb. comprises a group of highly diversified dinoflagellates. Their morphological taxonomy has been established over the last century. Here, we examined relationships within the genus Peridinium, including Peridinium bipes F. Stein sensu lato, based on a molecular phylogeny derived from nuclear rDNA sequences. Extensive rDNA analyses of nine selected Peridinium species showed that intraspecies genetic variation was considerably low, but interspecies genetic divergence was high (>1.5% dissimilarity in the nearly complete 18S sequence; >4.4% in the 28S rDNA D1/D2). The 18S and 28S rDNA Bayesian tree topologies showed that Peridinium species grouped according to their taxonomic positions and certain morphological characters (e.g., epithecal plate formula). Of these groups, the quinquecorne group (plate formula of 3′, 2a, 7″) diverged first, followed by the umbonatum group (4′, 2a, 7″) and polonicum group (4′, 1a, 7″). Peridinium species with a plate formula of 4′, 3a, 7″ diverged last. Thus, 18S and 28S rDNA D1/D2 sequences are informative about relationships among Peridinium species. Statistical analyses revealed that the 28S rDNA D1/D2 region had a significantly higher genetic divergence than the 18S rDNA region, suggesting that the former as DNA markers may be more suitable for sequence‐based delimitation of Peridinium. The rDNA sequences had sufficient discriminative power to separate P. bipes f. occultaum (Er. Lindem.) M. Lefèvre and P. bipes f. globosum Er. Lindem. into two distinct species, even though these taxa are morphologically only marginally discriminated by spines on antapical plates and the shape of red bodies during the generation of cysts. Our results suggest that 28S rDNA can be used for all Peridinium species to make species‐level taxonomic distinctions, allowing improved taxonomic classification of Peridinium.     

PHYLOGENY AND SYSTEMATICS OF THE MARINE ALGAL FAMILY GRACILARIACEAE (GRACILARIALES,RHODOPHYTA) BASED ON SMALL SUBUNIT rDNA AND ITS SEQUENCES OF ATLANTIC AND PACIFIC SPECIES1

We sequenced the small subunit rDNA and internal transcribed spacer region of Gracilariaceae from the tropical Atlantic and Pacific, with emphasis on flattened or compressed species. Sequence comparisons confirmed three main lineages of Gracilariaceae: Curdiea/Melanthalia, Gracilariopsis/Gracilariophila, and Gracilaria. The Curdiea/Melanthalia diverged early in the family. Gracilariopsis was paraphyletic, because at least one Gracilariophila species evolved from it. The Atlantic Gracilariopsis were monophyletic and separated from the Pacific lineages. The Gracilaria included all species referable to its own species and to Hydropuntia, which was paraphyletic, formed by distantly related lineages. The new combination Gracilaria pauciramosa (N. Rodríguez Ríos) Bellorin, M. C. Oliveira et E. C. Oliveira is proposed for Polycavernosa pauciramosa N. Rodríguez Ríos. Recognition of subgenera within Gracilaria, based on spermatangial arrangement, was not supported. Instead, infrageneric groups were delineated by geographic origins and combinations of reproductive characters. Most Pacific species with either “textorii” or “verrucosa” type spermatangia were deeply separated from Atlantic species. Within the Atlantic Gracilaria, a lineage encompassing mostly tropical cylindrical species with “henriquesiana” type spermatangia and distinctive cystocarp anatomy was recognized. A lineage was also retrieved for cold water stringy species with verrucosa type spermatangia. Several species from the western Atlantic are closely related to Gracilaria tikvahiae McLachlan with nearly identical morphology. On the other hand, most flattened species from the tropical Atlantic were closely related despite their diverse morphologies. The interpretation of our data in addition to the literature indicates that more populations from the Indo‐Pacific must be studied before a general picture of Gracilariaceae evolution can be framed.     

PHYLOGENY AND SYSTEMATICS OF THE GENUS MONOMORPHINA (EUGLENACEAE) BASED ON MORPHOLOGICAL AND MOLECULAR DATA1

Morphological studies of 16 strains belonging to the genus Monomorphina revealed a single, parietal, orbicular chloroplast in their cells. The chloroplast has a tendency to be perforated and disintegrates in aging populations and thus may appear to be many chloroplasts under the light microscope. A single chloroplast in the cells of Cryptoglena skujae is also parietally located and highly perforated. It never forms a globular and closed structure, but is open from the side of the furrow, resembling the letter C. We have verified the Monomorphina pyrum group (M. pyrum–like) on the basis of phylogenetic analysis of SSU rDNA and morphological data. The strain CCAC 0093 (misidentified as M. reeuwykiana) diverges first on the SSU rDNA phylogenetic tree. The rest of the M. pyrum–like strains form a tight cluster, subdivided into several smaller ones. Because morphological differences between the M. pyrum–like strains (including the strain CCAC 0093) do not conform to the tree topology, we suggest that they all (except the strain CCAC 0093) belong to M. pyrum. We designate a new species, M. pseudopyrum, for the strain CCAC 0093, solely on the basis of molecular characters. We also suggest that M. reeuwykiana and similar species should stay in Phacus and Lepocinclis unless detailed molecular and morphological studies show otherwise. Emended diagnoses of the genera Monomorphina and Cryptoglena and the species M. aenigmatica are also proposed, as well as the delimitation of an epitype for M. pyrum, the type species for the genus Monomorphina.     

PHYLOGENY OF THE EUGLENOID LORICATE GENERA TRACHELOMONAS AND STROMBOMONAS (EUGLENOPHYTA) INFERRED FROM NUCLEAR SSU AND LSU rDNA1

Previous studies using the nuclear SSU rDNA and partial LSU rDNA have demonstrated that the euglenoid loricate taxa form a monophyletic clade within the photosynthetic euglenoid lineage. It was unclear, however, whether the loricate genera Trachelomonas and Strombomonas were monophyletic. In order to determine the relationships among the loricate taxa, SSU and LSU nuclear rDNA sequences were obtained for eight Strombomonas and 25 Trachelomonas strains and combined in a multigene phylogenetic analysis. Conserved regions of the aligned data set were used to generate maximum‐likelihood (ML) and Bayesian phylogenies. Both methods recovered a strongly supported monophyletic loricate clade with Strombomonas and Trachelomonas species separated into two sister clades. Taxa in the genus Strombomonas sorted into three subclades. Within the genus Trachelomonas, five strongly supported subclades were recovered in all analyses. Key morphological features could be attributed to each of the subclades, with the major separation being that all of the spine‐bearing taxa were located in two sister subclades, while the more rounded, spineless taxa formed the remaining three subclades. The separation of genera and subclades was supported by 42 distinct molecular signatures (33 in Trachelomonas and nine in Strombomonas). The morphological and molecular data supported the retention of Trachelomonas and Strombomonas as separate loricate genera.     

ASTEROMENIA (RHODYMENIACEAE,RHODYMENIALES), A NEW RED ALGAL GENUS BASED ON FAUCHEA PELTATA1

Asteromenia gen. nov. (Rhodymeniales, Rhodophyta) is proposed with a single species, Asteromenia peltata (W. R. Taylor) comb. nov. (basionym: Fauchea peltata W. R. Taylor). Thalli of the proposed new genus are stipitate with dorsiventral, peltate blades that are initially circular in shape but with age become stellate with ligulate arms. Internally, the blades have a polystromatic medulla of large, hyaline cells, grading into a cortex of smaller, pigmented cells. Clusters of translucent cells occur on the dorsal surface of the blade. Tetrasporangia are formed by transformations of intercalary midcortical cells. Mature tetrasporangia have cruciately arranged spores and are densely aggregated in the cortex, mostly on the ventral surface, but occasional tetrasporangia also arise on the dorsal surface. Carpogonial branches are four-celled and arise on inner cortical cells. Auxiliary cells are borne on auxiliary mother cells attached to supporting cells of the carpogonial branches. Cystocarps are protuberant, with well-developed, ostiolate pericarps that often have extended, proboscis-like necks. The new genus differs from the previously described peltate or dorsiventral taxa in the Rhodymeniaceae by its polystromatic medulla (Maripelta and Sciadophycus have a monostromatic medulla), intercalary tetrasporangia formed in an unmodified cortex, and four-celled carpogonial branches (Halichrysis, as typified by H. depressa (J. Agardh) F. Schmitz, has terminal tetrasporangia in nemathecia and three-celled carpogonial branches).     

PARASITIC SPECIES OF THE GENUS BLASTODINIUM (BLASTODINIPHYCEAE) ARE PERIDINIOID DINOFLAGELLATES1

The taxonomic position of Blastodinium navicula Chatton and B. contortum Chatton, parasites of marine copepods, was investigated on the basis of morphological observations and molecular data. The life cycle of Blastodinium includes a parasitic stage, a trophont, and free‐swimming dinospores. The individual cells in the trophont, as well as the dinospores that they produced, were thecate. Dinospores of B. contortum and B. navicula had peridinioid plate tabulation formula, demonstrating an affiliation to the order Peridiniales Heackel (subdivision Dinokaryota Fensome et al.). This systematic position is in contrast to current classifications, in which the order Blastodiniales Chatton is thought to represent an early evolutionary branch of the dinokaryote lineage. Small‐subunit rRNA gene sequences were generated from six Blastodinium individuals isolated from three different host species. In phylogenetic analyses based on SSU rRNA genes, Blastodinium spp. branched with the typical dinoflagellates. Even though overall statistical support was low, the analyses suggested that Blastodinium spp. are late‐branching, dinokaryote dinoflagellates. Species currently included in Blastodiniales are all parasites, but they are morphologically and functionally diverse. Emerging molecular data also reveal high genetic diversity, and therefore, the taxonomy of the group requires reevaluation.     

PHYLOGENY OF THE DUMONTIACEAE (GIGARTINALES, RHODOPHYTA) AND ASSOCIATED FAMILIES BASED ON SSU rDNA AND INTERNAL TRANSCRIBED SPACER SEQUENCE DATA

Small subunit (SSU) rDNA was sequenced for 25 species in 19 genera of the Gigartinales (Rhodophyta). As well, the internal transcribed spacer (ITS) region was sequenced, and a data matrix of 36 morphological characters was constructed for 16 species of Dumontiaceae. Phylogenetic trees were calculated from a multiple alignment of the SSU sequence data to infer relationships between species of Dumontiaceae and other gigartinalean taxa. The SSU analysis produced a polyphyletic Dumontiaceae. Notably, Acrosymphyton failed to associate with the included Gigartinales, let alone the Dumontiaceae, supporting an earlier proposal to remove it to a new family. The analyses were equivocal about the phylogenetic affinities of Dudresnaya , which clustered with the Kallymeniaceae, and the affinities of the Indo-West Pacific Gibsmithia , Kraftia , and Dasyphloea , the last-mentioned clustering with the Antarctic Gainiaceae, and these four taxa with Portieria (Rhizophyllidaceae). Further investigations are necessary to resolve relationships among these taxa. Rhodopeltis , a genus recently moved to the Dumontiaceae from the Polyideaceae, showed a weak association with the remaining northern Dumontiaceae. The final group consisted of cold-temperate Northern Hemisphere species. Phylogenetic analyses using a combination of SSU, ITS, and morphological data within this clade produced two strongly supported clades, a Dilsea / Neodilsea clade and a Cryptosiphonia / Dumontia clade. Dilsea is derived from a paraphyletic Neodilsea and may itself be polyphyletic. Atlantic and Pacific isolates of Dumontia contorta clearly showed sufficient divergence to warrant recognition as distinct species, and Dumontia alaskana , sp. nov. is proposed for the Pacific species.     

MORPHOLOGY AND MOLECULAR PHYLOGENY OF PROROCENTRUM CONSUTUM SP. NOV. (DINOPHYCEAE), A NEW BENTHIC DINOFLAGELLATE FROM SOUTH BRITTANY (NORTHWESTERN FRANCE)1

A new marine benthic Prorocentrum species from sandy habitats of South Brittany (northwestern France), P. consutum sp. nov., is described using LM and SEM and molecular phylogenetic analyses. Cells have a subcircular to broadly ovoid shape and are plainly flattened. They are 57–61 μm long and 52–55 μm wide. A central pyrenoid is present, and the kidney‐shaped nucleus is positioned in the posterior region. In right valve view, the periflagellar area is deeply excavated, and the left valve forms a prominent apical ridge. The periflagellar area consists of nine platelets, and a small narrow collar is present around the flagellar pore. The ornamentation of this new species is very peculiar and is characterized by a ring of round areolae located at the periphery of the valves, each areola containing three or four pores. Apart from this ring of areolae, the cell surface is smooth and with scattered pores. Pores are not present in the center of the right or left valve. The intercalary band is generally narrow and faintly striated horizontally. The molecular phylogenetic position of P. consutum sp. nov. was inferred using SSU and LSU rDNA. In both analyses, this species branched with high support in the clade comprising species with a symmetric shape and appeared to be a sister group to that formed by P. lima and other tropical benthic species, such as P. arenarium, P. belizeanum, P. hoffmannianum, and P. maculosum.     

MOLECULAR PHYLOGENY AND PHENOTYPIC VARIATION IN THE HETEROTROPHIC GREEN ALGAL GENUS PROTOTHECA (TREBOUXIOPHYCEAE,CHLOROPHYTA)1

Species of the heterotrophic green microalgal genus Prototheca and related taxa were phylogenetically analyzed based on the nuclear small subunit (SSU) and the 5′ end of the large subunit (LSU) rRNA gene (rDNA) sequences. We propose restricting the genus Prototheca to the four species: P. moriformis Krüger, P. stagnora (Cooke) Pore, P. ulmea Pore, and P. zopfii Krüger. The main diagnostic feature of these taxa is the absence of growth on trehalose.Of these, it was suggested that P. moriformis should be merged into P. zopfii; P. moriformis and three varieties of P. zopfii constituted a paraphyletic assemblage with estimated short evolutionary distances. The trehalose‐assimilating strains (Prototheca wickerhamii Tubaki et Soneda strains and Auxenochlorella protothecoides (Krüger) Kalina et Pun?ochá?ová SAG 211‐7a), together with an invertebrate pathogen Helicosporidium sp., diverged before the radiation of the four species of Prototheca in the SSU rDNA and composite (SSU rDNA plus LSU rDNA) analyses. Comparison between the results from physiological data in this work (fermentative pattern) and those described earlier (growth requirements) lead us to propose a hypothesis that the phenotypic variation, which did not represent diagnostic characters for species delimitation, may reflect the history of genetic diversification within the genus Prototheca as inferred from rDNA sequence characters.     

UPDATING THE GENUS DICTYOSPHAERIUM AND DESCRIPTION OF MUCIDOSPHAERIUM GEN. NOV. (TREBOUXIOPHYCEAE) BASED ON MORPHOLOGICAL AND MOLECULAR DATA1

Recent molecular analyses of Dictyosphaerium strains revealed a polyphyletic origin of this morphotype within the Chlorellaceae. The type species Dictyosphaerium ehrenbergianum Nägeli formed an independent lineage within the Parachlorella clade, assigning the genus to this clade. Our study focused on three different Dictyosphaerium species to resolve the phylogenetic position of remaining species. We used combined analyses of morphology; molecular data based on SSU and internally transcribed spacer region (ITS) rRNA sequences; and the comparison of the secondary structure of the SSU, ITS‐1, and ITS‐2 for species and generic delineation. The phylogenetic analyses revealed two lineages without generic assignment and two distinct clades of Dictyosphaerium‐like strains within the Parachlorella clade. One clade comprises the lineages with the epitype strain of D. ehrenbergianum Nägeli and two additional lineages that are described as new species (Dictyosphaerium libertatis sp. nov. and Dictyosphaerium lacustre sp. nov.). An emendation of the genus Dictyosphaerium is proposed. The second clade comprises the species Dictyosphaerium sphagnale Hindák and Dictyosphaerium pulchellum H. C. Wood. On the basis of phylogenetic analyses, complementary base changes, and morphology, we describe Mucidosphaerium gen. nov with the four species Mucidosphaerium sphagnale comb. nov., Mucidosphaerium pulchellum comb. nov., Mucidosphaerium palustre sp. nov., and Mucidosphaerium planctonicum sp. nov.     

MONOPHYLY OF THE GENUS CLOSTERIUM AND THE ORDER DESMIDIALES (CHAROPHYCEAE, CHLOROPHYTA) INFERRED FROM NUCLEAR SMALL SUBUNIT rDNA DATA

We newly sequenced the nuclear-encoded small subunit (SSU) rDNA coding region for 21 taxa of the genus Closterium. The new sequences were integrated into an alignment with 13 known sequences of conjugating green algae representing six traditional families (i.e. Zygnemataceae, Mesotaeniaceae, Gonatozygaceae, Peniaceae, Closteriaceae, and Desmidiaceae) and five known charophycean sequences as outgroups. Both maximum likelihood and maximum parsimony analyses supported with high bootstrap values one large clade containing all placoderm desmids (Desmidiales). All the Closterium taxa formed one clade with 100% bootstrap support, indicating their monophyly, but not paraphyly, as suggested earlier. As to the taxa within the genus Closterium , we found two clades of morphologically closely related taxa in both maximum likelihood and maximum parsimony trees. They corresponded to the C. calosporum species complex and the C. moniliferum-ehrenbergii species complex. It is of particular interest that the homothallic entity of C. moniliferum v. moniliferum was distinguished from and ancestral to all other entities of the C. moniliferum-ehrenbergii species complex. Superimposing all 50 charophycean sequences on the higher order SSU rRNA structure model of Closterium , we investigated degrees of nucleotide conservation at a given position in the nucleotide sequence. A characteristic "signature" structure to the genus Closterium was found as an additional helix at the tip of V1 region. In addition, eight base deletions at the tip of helix 10 were found to be characteristic of the C. calosporum species complex, C. gracile , C. incurvum , C. pleurodermatum , and C. pusillum v. maius. These taxa formed one clade with an 82% bootstrap value in maximum parsimony analysis.     

MOLECULAR EVOLUTION OF EUGLENOZOAN PARAXONEMAL ROD GENES par1 AND par2 COINCIDES WITH PHYLOGENETIC RECONSTRUCTION BASED ON SMALL SUBUNIT rDNA DATA1

Emergent flagella of Euglenozoa consist of two prominent structural elements: the axoneme built by microtubules with motor proteins to enable the movement of the flagellum and a highly organized protein structure of unknown function, called the paraxonemal rod (PAR), which consists of two major proteins paralleling the axoneme of euglenid and kinetoplastid emergent flagella. These flagellar structures are considered apomorphic characters of Euglenozoa. We examined the evolution of the genes par1 and par2 encoding the two major proteins, where we could show that these proteins are encoded by two very similar genes found in kinetoplastids and euglenids. The branching pattern indicated a gene duplication before the diversification into euglenids and kinetoplastids. In the clades of the genes, subtrees of euglenid and kinetoplastid monophyla arose. Both genes showed strong genetic diversity with biased GC content at taxon rather than at gene level. We also examined phylogenies inferred from PAR genes that are well in agreement with established small subunit rDNA analyses. Both showed further separation of the euglenid subtree into primary osmotrophs and a phototrophic clade, including secondarily derived osmotrophs.     

A PHYLOGENETIC STUDY OF THE CORALLINALES (RHODOPHYTA) BASED ON NUCLEAR SMALL-SUBUNIT rRNA GENE SEQUENCES

Conflicting classifications for the Corallinales were tested by analyzing partial sequences for the nuclear small-subunit ribosomal RNA (SSU) gene of 35 species of coralline algae. Parsimony and likelihood analyses of these data yielded congruent hypotheses that are inconsistent with classifications for the group that include as many as eight subfamilies. Four major clades are resolved within the order, including the early-diverging Sporolithaceae as well as the Melobesioideae and Corallinoideae. The fourth clade, which is supported robustly, includes both nongeniculate and geniculate species classified in the subfamilies Mastophoroideae, Metagoniolithoideae, Lithophylloideae, and Amphiroideae. Molecular and morphological data support the proposal that the latter two subfamilies are sister taxa. Although relationships among some genera are not resolved clearly, the order of branching of taxa among and within the four principal lineages is concordant with paleontological evidence for the group. Relationships inferred among genera within each of the clades is discussed. Seven morphological characters delimiting higher taxonomic groups within the order were combined with the sequence data, analyzed, and optimized onto the resulting tree(s). Except for the presence or absence of genicula, all other characters were found to be phylogenetically informative. Genicula are nonhomologous structures that evolved independently in the Amphiroideae, Corallinoideae, and Metagoniolithoideae. The phenetic practice of separating coralline algae into two categories solely on the basis of the presence or absence of genicula does not accurately reflect the evolutionary history of the group.     

CERAMIUM INKYUII SP. NOV. (CERAMIACEAE,RHODOPHYTA) FROM KOREA: A NEW SPECIES BASED ON MORPHOLOGICAL AND MOLECULAR EVIDENCE1

Ceramium inkyuii sp. nov. is newly described based on samples collected from the east coast of Korea and compared with similar species such as C. paniculatum and C. tenerrimum. The new species is characterized by pseudo‐dichotomously branched thalli with a twist in the upper part, a single row of spines on the abaxial side, strongly inrolled apices, and the presence of gland cells. In contrast, C. paniculatum has alternate branches and lacks gland cells, and C. tenerrimum is spineless and also lacks gland cells. Ceramium inkyuii was observed to be an annual species producing tetrasporangia in the spring to summer and cystocarps in the fall. Plastid‐encoded rbcL and nuclear small subunit (SSU) rDNA sequences were determined in four samples of C. inkyuii from different locations and six samples of four putative relatives. All four C. inkyuii replicates from three different locations had identical sequences of each gene, and the interspecific sequence divergences were enough to warrant its natural entity. The phylogenies of the rbcL and SSU rDNA sequences also indicate the monophyly of C. inkyuii. The spinous C. inkyuii was more closely related to the spineless C. tenerrimum than to the spinous C. paniculatum.     

MORPHOLOGY AND MOLECULAR PHYLOGENY OF ANKISTRODINIUM GEN. NOV. (DINOPHYCEAE), A NEW GENUS OF MARINE SAND‐DWELLING DINOFLAGELLATES FORMERLY CLASSIFIED WITHIN AMPHIDINIUM1

The classical athecate dinoflagellate genera (Amphidinium, Gymnodinium, Gyrodinium) have long been recognized to be polyphyletic. Amphidinium sensu lato is the most diverse of all marine benthic dinoflagellate genera; however, following the redefinition of this genus ～100 species remain now of uncertain or unknown generic affiliation. In an effort to improve our taxonomic and phylogenetic understanding of one of these species, namely Amphidinium semilunatum, we re‐investigated organisms from several distant sites around the world using light and scanning electron microscopy and molecular phylogenetic methods. Our results enabled us to describe this species within a new heterotrophic genus, Ankistrodinium. Cells of A. semilunatum were strongly laterally flattened, rounded‐quadrangular to oval in lateral view, and possessed a small asymmetrical epicone. The sulcus was wide and characteristically deeply incised on the hypocone running around the antapex and reaching the dorsal side. The straight acrobase with hook‐shaped end started at the sulcal extension and continued onto the epicone. The molecular phylogenetic results clearly showed that A. semilunatum is a distinct taxon and is only distantly related to species within the genus Amphidinium sensu stricto. The nearest sister group to Ankistrodinium could not be reliably determined.     

THE NEW GENUS YONAGUNIA KAWAGUCHI ET MASUDA (HALYMENIACEAE,RHODOPHYTA), BASED ON Y. TENUIFOLIA KAWAGUCHI ET MASUDA SP. NOV. FROM SOUTHERN JAPAN AND INCLUDING Y. FORMOSANA (OKAMURA) KAWAGUCHI ET MASUDA COMB. NOV. FROM SOUTHEAST ASIA1

Yonagunia Kawaguchi et Masuda, gen. nov. (Halymeniaceae, Rhodophyta) is proposed to accommodate a new species, Yonagunia tenuifolia Kawaguchi et Masuda and the species currently known as Prionitis formosana (Okamura) Kawaguchi et Nguyen. Based on auxiliary cell ampullar features, Yonagunia is included in the group of genera with the simplest type of ampulla (the Grateloupia type) that comprises Dermocorynus, Grateloupia, Kintokiocolax, Phyllymenia, and Zymurgia. However, Yonagunia differs from these genera in the behavior of cells in the ampullar filaments immediately after diploidization, most cells of the primary and secondary filaments simultaneously dividing to form grape‐like clusters of small globular cells that subsequently elongate and produce involucral filaments to laxly surround the maturing carposporophyte. Yonagunia is resolved by our rbcL gene sequence analyses as one of five monophyletic clades within the Halymeniaceae (an Aeodes/Pachymenia, a Polyopes, a Carpopertis/Cryptonemia/Halymenia, a Yonagunia, and a Grateloupia clade) that is positioned as sister to the Grateloupia clade. Carpogonial branch apparatuses are identified as a potential taxonomic significance on the same level as auxiliary cell ampullae.