Nuclear SSU Research Articles

Paravannella minima n. g. n. sp. (Discosea, Vannellidae) and distinction of the genera in the vannellid amoebae

Paravannella minima n. g. n. sp. (Amoebozoa, Vannellidae) isolated from a freshwater aquarium, possesses all light-microscopic and ultrastructural characteristics of the genus Vannella, being one of the smallest species among the vannellid amoebae (cell size during locomotion usually between 4.5 and 10μm). At the same time, sequence analysis of the genes encoding for nuclear SSU rRNA, actin and mitochondrial Cox1 shows this species as the earliest-branching vannellid that appears to be sister to the rest of this clade. This is correlated with the presence of some plesiomorphic characters; in particular, the secondary structure of the hypervariable helices E23-1–E23-7 in the studied species is shared with Vannella and most of the genera of Dactylopodida. The cell coat structure of the studied species corresponds to the hypothesis that vannellid amoebae were ancestrally enclosed in a cell coat consisting of pentagonal glycostyles that have undergone multiple independent losses in various clades of Vannellidae.

GENETIC DIVERSITY OF Pyramimonas FROM RYUKYU ARCHIPELAGO, JAPAN (CHLOROPHYCEAE, PYRAMIMONADALES)

The genus Pyramimonas Schmarda was traditionally described on observations of its periplast and internal structure of different flagellar apparatus or eyespot orientations and currently comprises of ca. 60 species that are divided into six subgenera: Pyramimonas, Vestigifera, Trichocystis, Punctatae, Hexactis, and Macrura. In order to understand the genetic diversity and phylogenetic relationships of genus Pyramimonas members, we analyzed nuclear SSU rDNA molecular data from 41 strains isolated from different locations of the Ryukyu Archipelago. Phylogenetic analyses revealed that strains could be segregated into six clades, four of which represented existing subgenera: Pyramimonas, Vestigifera McFadden, Trichocystis McFadden, and Punctatae McFadden, and two undescribed subgenera. Most recovered subgenera were represented by established and confirmed species of Pyramimonas along with several potentially undescribed species with the exception of one undescribed subgenus. Many of the newly isolated strains were closely related with Pyramimonas aurea and P. olivacea, and were considered to belong to subgenus Punctatae. However, nuclear SSU rDNA phylogenetic trees clearly showed that they are genetically different and can be divided into two subgenera. Subgenus Punctatae comprised of Pyramimonas olivacea and related strains whilst, P. aurea and related strains belonged to an undescribed subgenus which is tentatively referred to as undescribed subgenus 1 which shared a sister-group relationship with subgenus Punctatae. The genetic similarity based on nuclear SSU rDNA ranged from 98.2% to 99.9% and 97.3% to 98.3% within and between subgenera, respectively. The present work shows high level of genetic diversity for the genus Pyramimonas from the Ryukyu Archipelago, Japan.

A molecular perspective on generic concepts in the Hypotrachyna clade (Parmeliaceae, Ascomycota)

Recently, molecular phylogenetic studies have revolutionized the generic concepts in Parmeliaceae and in lichen forming fungi in general. In the present study, the generic delimitation in the Hypotrachyna clade is revised using a molecular phylogeny of nuclear ITS, LSU and mitochondrial SSU rDNA sequences of 88 hypotrachynoid taxa. Morphological and chemical features are also revised in each group. 118 sequences are newly generated for this study. Our phylogenetic analyses show the polyphyly of Hypotrachyna as currently circumscribed which falls into four well-supported and one unsupported clade. Cetrariastrum, Everniastrum and Parmelinopsis are nested within Hypotrachyna s. lat., Parmelinopsis being also polyphyletic and nested in one of the Hypotrachyna clades. Cetrariastrum is monophyletic but clustered within Everniastrum. Two alternative hypotheses tests significantly rejected the monophyly of these three genera. As a consequence, the genera Cetrariastrum, Everniastrum, and Parmelinopsis are reduced to synonymy with Hypotrachyna. Furthermore, we here propose an alternative classification to recognize the well-supported clades at subgeneric level and leave the remaining species unclassified within the genus. Five new subgenera are proposed: Hypotrachyna subgen. Cetrariastrum, Hypotrachyna subgen. Everniastrum, Hypotrachyna subgen. Longilobae, Hypotrachyna subgen. Parmelinopsis, and Hypotrachyna subgen. Sinuosae. Forty-nine new combinations are proposed.

Multi-gene phylogenetic analyses reveal species limits, phylogeographic patterns, and evolutionary histories of key morphological traits in <I>Entoloma</I> (<I>Agaricales</I>, <I>Basidiomycota</I>)

Species from Entoloma subg. Entoloma are commonly recorded from both the Northern and Southern Hemispheres and, according to literature, most of them have at least Nearctic-Palearctic distributions. However, these records are based on morphological analysis, and studies relating morphology, molecular data and geographical distribution have not been reported. In this study, we used phylogenetic species recognition criteria through gene genealogical concordance (based on nuclear ITS, LSU, rpb2 and mitochondrial SSU) to answer specific questions considering species limits in Entoloma subg. Entoloma and their geographic distribution in Europe, North America and Australasia. The studied morphotaxa belong to sect. Entoloma, namely species like the notorious poisonous E. sinuatum (E. lividum auct.), E. prunuloides (type-species of sect. Entoloma), E. nitidum and the red-listed E. bloxamii. With a few exceptions, our results reveal strong phylogeographical partitions that were previously not known. For example, no collection from Australasia proved to be conspecific with the Northern Hemisphere specimens. Almost all North American collections represent distinct and sister taxa to the European ones. And even within Europe, new lineages were uncovered for the red-listed E. bloxamii, which were previously unknown due to a broad morphological species concept. Our results clearly demonstrate the power of the phylogenetic species concept to reveal evolutionary units, to redefine the morphological limits of the species addressed and to provide insights into the evolutionary history of key morphological characters for Entoloma systematics. New taxa are described, and new combinations are made, including E. fumosobrunneum, E. pseudoprunuloides, E. ochreoprunuloides and E. caesiolamellatum. Epitypes are selected for E. prunuloides and E. bloxamii. In addition, complete descriptions are given of some other taxa used in this study for which modern descriptions are lacking, viz. E. subsinuatum, E. whiteae, E. flavifolium, E. luridum, E. bloxamii, E. madidum, E. corneri, E. callidermum and E. coeruleoviride.

A new photosynthetic euglenoid isolated in Poland: Euglenaria clepsydroides sp. nov. (Euglenea)

In this paper, we describe a new photosynthetic euglenoid species, Euglenaria clepsydroides Zakryś, sp. nov., found in Poland. A large population of this species exists in a few, small, eutrophic bodies of water inside the Masurian Landscape Park (covering a part of the Masurian Lake District in Poland). The characteristic and atypical (hourglass-like) cell shape sets it well apart from the other species that have been described up to now. This atypical cell shape has so far been observed only in three species – Lepocinclis constricta, Euglena undulata and Euglena gymnodinioides – whose other morphological characteristics, such as the number and morphology of chloroplasts, the lack of mucocysts, and nuclear SSU rDNA sequence data, exclude the possibility that they could be close relatives of Euglenaria clepsydroides. On the phylogenetic tree, the new species is situated within the Euglenaria clade. While it is a sister group of the clade that includes representatives of Euglenaria anabaena, the two species are clearly morphologically distinct.

A Dinoflagellate Amylax triacantha with Plastids of the Cryptophyte Origin: Phylogeny, Feeding Mechanism, and Growth and Grazing Responses

The gonyaulacalean dinoflagellates Amylax spp. were recently found to contain plastids of the cryptophyte origin, more specifically of Teleaulax amphioxeia. However, not only how the dinoflagellates get the plastids of the cryptophyte origin is unknown but also their ecophysiology, including growth and feeding responses as functions of both light and prey concentration, remain unknown. Here, we report the establishment of Amylax triacantha in culture, its feeding mechanism, and its growth rate using the ciliate prey Mesodinium rubrum (= Myrionecta rubra) in light and dark, and growth and grazing responses to prey concentration and light intensity. The strain established in culture in this study was assigned to A. triacantha, based on morphological characteristics (particularly, a prominent apical horn and three antapical spines) and nuclear SSU and LSU rDNA sequences. Amylax triacantha grew well in laboratory culture when supplied with the marine mixotrophic ciliate M. rubrum as prey, reaching densities of over 7.5×10(3) cells/ml. Amylax triacantha captured its prey using a tow filament, and then ingested the whole prey by direct engulfment through the sulcus. The dinoflagellate was able to grow heterotrophically in the dark, but the growth rate was approximately two times lower than in the light. Although mixotrophic growth rates of A. triacantha increased sharply with mean prey concentrations, with maximum growth rate being 0.68/d, phototrophic growth (i.e. growth in the absence of prey) was -0.08/d. The maximum ingestion rate was 2.54ng C/Amylax/d (5.9cells/Amylax/d). Growth rate also increased with increasing light intensity, but the effect was evident only when prey was supplied. Increased growth with increasing light intensity was accompanied by a corresponding increase in ingestion. In mixed cultures of two predators, A. triacantha and Dinophysis acuminata, with M. rubrum as prey, A. triacantha outgrew D. acuminata due to its approximately three times higher growth rate, suggesting that it can outcompete D. acuminata. Our results would help better understand the ecophysiology of dinoflagellates retaining foreign plastids.

Validating the identity of Paramoeba invadens, the causative agent of recurrent mass mortality of sea urchins in Nova Scotia, Canada

Green sea urchins Strongylocentrotus droebachiensis along the coast of Nova Scotia, Canada, suffer mass mortalities from infection by the pathogenic amoeba Paramoeba invadens Jones, 1985. It has been speculated that P. invadens could be a form of Neoparamoeba pemaquidensis, a species associated with disease in S. droebachiensis and lobsters in the northeast USA. During a disease outbreak in fall 2011, we isolated amoebae from moribund urchins collected from 4 locations along ~200 km of coastline. In laboratory infection trials, we found that timing and rate of morbidity corresponded to that of similar experiments conducted in the early 1980s, when P. invadens was first identified. All isolates had a similar size and morphology to the original description, including an absence of microscales. Sequences of nuclear SSU rDNA show that disease was caused by one 'species' of amoeba across the range sampled. Phylogenetic analyses prove that P. invadens is not conspecific with N. pemaquidensis, but is a distinct species most closely related to N. branchiphila, a suspected pathogen of sea urchins Diadema aff. antillarum in the Canary Islands, Spain. Morphology and closest phylogenetic affinities suggest that P. invadens would be assignable to the genus Neoparamoeba; however, nuclear SSU rDNA trees show that Neoparamoeba and Paramoeba are phylogenetically inseparable. Therefore, we treat Neoparamoeba as a junior synonym of Paramoeba, with P. invadens retaining that name, and N. pemaquidensis and N. aestuarina reverting to their original names (P. pemaquidensis and P. aestuarina), and with new combinations for N. branchiphila Dykova et al., 2005, and N. perurans Young et al., 2007, namely P. branchiphila comb. nov. and P. perurans comb. nov.

Global sampling of plant roots expands the described molecular diversity of arbuscular mycorrhizal fungi

We aimed to enhance understanding of the molecular diversity of arbuscular mycorrhizal fungi (AMF) by building a new global dataset targeting previously unstudied geographical areas. In total, we sampled 96 plant species from 25 sites that encompassed all continents except Antarctica. AMF in plant roots were detected by sequencing the nuclear SSU rRNA gene fragment using either cloning followed by Sanger sequencing or 454-sequencing. A total of 204 AMF phylogroups (virtual taxa, VT) were recorded, increasing the described number of Glomeromycota VT from 308 to 341 globally. Novel VT were detected from 21 sites; three novel but nevertheless widespread VT (Glomus spp. MO-G52, MO-G53, MO-G57) were recorded from six continents. The largest increases in regional VT number were recorded in previously little-studied Oceania and in the boreal and polar climatic zones - this study providing the first molecular data from the latter. Ordination revealed differences in AM fungal communities between different continents and climatic zones, suggesting that both biogeographic history and environmental conditions underlie the global variation of those communities. Our results show that a considerable proportion of Glomeromycota diversity has been recorded in many regions, though further large increases in richness can be expected in remaining unstudied areas.

The complete mitochondrial genome from an unidentified Phalansterium species.

We describe the complete sequence and organization of the mitochondrial genome from an unidentified species of Phalansterium. This is the first sequenced mitochondrial genome of a member of Variosea clade (Amoebozoa, Conosa). The sequence was assembled from shotgun reads of DNA from a mixed culture containing the euglenid Monomorphina aenigmatica and an amoebozoan that we demonstrate here is closely related to Phalansterium (in nuclear SSU rRNA phylogenies, it branches between two sequences from described species of Phalansterium). Sequence assembly resulted in two distinct mitochondrial genome types, one fragmented and euglenid-like, and the second a single circular- mapping contig of 53,614 bp with an amoebozoan-like set of genes. The Phalansterium sp. mitochondrial genome is gene-rich and densely packed, with a large number of tRNAs and an unusually low ratio of identifiable protein-coding genes to unidentified ORFs. These ORFs potentially encode ribosomal proteins exhibiting a divergent character at the sequence level, and whose identification may be hindered by the presence of RNA editing in Phalansterium mitochondria, as inferred from numerous acceptor stem mis-matches typical of amoebozoan tRNA 5' editing.

Comparative analysis of complete mitochondrial genome sequences confirms independent origins of plant-parasitic nematodes

BackgroundThe nematode infraorder Tylenchomorpha (Class Chromadorea) includes plant parasites that are of agricultural and economic importance, as well as insect-associates and fungal feeding species. Among tylenchomorph plant parasites, members of the superfamily Tylenchoidea, such as root-knot nematodes, have great impact on agriculture. Of the five superfamilies within Tylenchomorpha, one (Aphelenchoidea) includes mainly fungal-feeding species, but also some damaging plant pathogens, including certain Bursaphelenchus spp. The evolutionary relationships of tylenchoid and aphelenchoid nematodes have been disputed based on classical morphological features and molecular data. For example, similarities in the structure of the stomatostylet suggested a common evolutionary origin. In contrast, phylogenetic hypotheses based on nuclear SSU ribosomal DNA sequences have revealed paraphyly of Aphelenchoidea, with, for example, fungal-feeding Aphelenchus spp. within Tylenchomorpha, but Bursaphelenchus and Aphelenchoides spp. more closely related to infraorder Panagrolaimomorpha. We investigated phylogenetic relationships of plant-parasitic tylenchoid and aphelenchoid species in the context of other chromadorean nematodes based on comparative analysis of complete mitochondrial genome data, including two newly sequenced genomes from Bursaphelenchus xylophilus (Aphelenchoidea) and Pratylenchus vulnus (Tylenchoidea).ResultsThe complete mitochondrial genomes of B. xylophilus and P. vulnus are 14,778 bp and 21,656 bp, respectively, and identical to all other chromadorean nematode mtDNAs in that they contain 36 genes (lacking atp8) encoded in the same direction. Their mitochondrial protein-coding genes are biased toward use of amino acids encoded by T-rich codons, resulting in high A+T richness. Phylogenetic analyses of both nucleotide and amino acid sequence datasets using maximum likelihood and Bayesian methods did not support B. xylophilus as most closely related to Tylenchomorpha (Tylenchoidea). Instead, B. xylophilus, was nested within a strongly supported clade consisting of species from infraorders Rhabditomorpha, Panagrolaimomorpha, Diplogasteromorpha, and Ascaridomorpha. The clade containing sampled Tylenchoidea (P. vulnus, H. glycines, and R. similis) was sister to all analyzed chromadoreans. Comparison of gene arrangement data was also consistent with the phylogenetic relationships as inferred from sequence data. Alternative tree topologies depicting a monophyletic grouping of B. xylophilus (Aphelenchoidea) plus Tylenchoidea, Tylenchoidea plus Diplogasteromorpha (Pristionchus pacificus), or B. xylophilus plus Diplogasteromorpha were significantly worse interpretations of the mtDNA data.ConclusionsPhylogenetic trees inferred from nucleotide and amino acid sequences of mtDNA coding genes are in agreement that B. xylophilus (the single representative of Aphelenchoidea) is not closely related to Tylenchoidea, indicating that these two groups of plant parasites do not share an exclusive most recent common ancestor, and that certain morphological similarities between these stylet-bearing nematodes must result from convergent evolution. In addition, the exceptionally large mtDNA genome size of P. vulnus, which is the largest among chromadorean nematode mtDNAs sequenced to date, results from lengthy repeated segments in non-coding regions.

Cryptic Speciation in the Genus Cryptoglena (Euglenaceae) Revealed by Nuclear and Plastid SSU and LSU rRNA Gene.

The photosynthetic euglenoid genus Cryptoglena is differentiated from other euglenoid genera by having a longitudinal sulcus, one chloroplast, two large trough-shaped paramylon plates positioned between the chloroplast and pellicle, and lack of metaboly. The genus contains only two species. To understand genetic diversity and taxonomy of Cryptoglena species, we analyzed molecular and morphological data from 25 strains. A combined data set of nuclear SSU and LSU and plastid SSU and LSU rRNA genes was analyzed using Bayesian, maximum likelihood, maximum parsimony, and distance (neighbor joining) methods. Although morphological data of all strains showed no significant species-specific pattern, molecular data segregated the taxa into five clades, two of which represented previously known species: C. skujae and C. pigra, and three of which were designated as the new species, C. soropigra, C. similis, and C. longisulca. Each species had unique molecular signatures that could be found in the plastid SSU rRNA Helix P23_1 and LSU rRNA H2 domain. The genetic similarity of intraspecies based on nr SSU rDNA ranged from 97.8% to 100% and interspecies ranged from 95.3% to 98.9%. Therefore, we propose three new species based on specific molecular signatures and gene divergence of the nr SSU rDNA sequences.

Phylogenetic Reappraisal of the Genus Monomorphina (Euglenophyceae) Based on Molecular and Morphological Data.

A morphological and molecular examination of the genus Monomorphina was conducted on 46 strains isolated mainly from Korea. The strains were divided into two types based on morphological data: Monomorphina aenigmatica and M. pyrum - like species. Phylogenetic analysis based on a combined data set of nuclear SSU and LSU and plastid SSU and LSU rDNA showed that the strains could be divided into eight clades: Clade A of M. aenigmatica, Clade B of the isolates (M. pyropsis) from Michigan, USA, Clade C of M. pseudopyrum, Clade D of the isolates (M. pyroria) from Bremen, Germany, Clade E of M. soropyrum, Clade F of M. pyriformis, Clade G of M. parapyrum, and Clade H of M. pyrum. Six of these clades came from strains that would be considered M. pyrum sensu Kosmala et Zakryś, one of which could be recognized as a traditional species (M. pyrum) and five were designated as new species; each species had unique molecular signatures at nr SSU rDNA helix 17 and 17' and spacer E23_14'-E23_15. The species of Monomorphina had a wide range of genetic diversity with interspecies sequence similarity of 85.6%-97.1% and intraspecies similarity of 96.4%-99.9%. Our results suggested that genetic diversity found in the M. pyrum complex justifies the recognition of a minimum of eight species within this genus, based on specific molecular signatures and gene divergence of the nr SSU rDNA sequences.

Molecular data support placement of Cameronia in Ostropomycetidae (Lecanoromycetes, Ascomycota)

The phylogenetic position of the Tasmanian endemic genus Cameronia Kantvilas is studied using partial sequences of nuclear LSU and mitochondrial SSU ribosomal DNA. Monophyly of the genus is supported, as is its placement in Ostropomycetidae, although its position within this subclass remains uncertain. Given the lack of close relatives to Cameronia and its morphological differences compared to other families with perithecioid ascomata in Ostropomycetidae, the new family Cameroniaceae Kantvilas & Lumbsch is proposed.

Strengths and weaknesses of microarray approaches to detect Pseudo-nitzschia species in the field

The planktonic diatom genus Pseudo-nitzschia contains several genetically closely related species. Some of these can produce domoic acid, a potent neurotoxin. Thus, monitoring programs are needed to screen for the presence of these toxic species. Unfortunately, many are impossible to distinguish using light microscopy. Therefore, we assessed the applicability of microarray technology for detection of toxic and non-toxic Pseudo-nitzschia species in the Gulf of Naples (Mediterranean Sea). Here, 11 species have been detected, of which at least 5 are potentially toxic. A total of 49 genus- and species-specific DNA probes were designed in silico against the nuclear LSU and SSU rRNA of 19 species, and spotted on the microarray. The microarray was tested against total RNA of monoclonal cultures of eight species. Only three of the probes designed to be species-specific were indeed so within the limits of our experimental design. To assess the effectiveness of the microarray in detecting Pseudo-nitzschia species in environmental samples, we hybridized total RNA extracted from 11 seasonal plankton samples against microarray slides and compared the observed pattern with plankton counts in light microscopy and with expected hybridization patterns obtained with monoclonal cultures of the observed species. Presence of species in field samples generally resulted in signal patterns on the microarray as observed with RNA extracted from cultures of these species, but many a-specific signals appeared as well. Possible reasons for the numerous cross reactions are discussed. Calibration curves for Pseudo-nitzschia multistriata showed linear relationship between signal strength and cell number.

PHYMYCO-DB: a curated database for analyses of fungal diversity and evolution.

BackgroundIn environmental sequencing studies, fungi can be identified based on nucleic acid sequences, using either highly variable sequences as species barcodes or conserved sequences containing a high-quality phylogenetic signal. For the latter, identification relies on phylogenetic analyses and the adoption of the phylogenetic species concept.Such analysis requires that the reference sequences are well identified and deposited in public-access databases. However, many entries in the public sequence databases are problematic in terms of quality and reliability and these data require screening to ensure correct phylogenetic interpretation.Methods and Principal FindingsTo facilitate phylogenetic inferences and phylogenetic assignment, we introduce a fungal sequence database. The database PHYMYCO-DB comprises fungal sequences from GenBank that have been filtered to satisfy stringent sequence quality criteria. For the first release, two widely used molecular taxonomic markers were chosen: the nuclear SSU rRNA and EF1-α gene sequences. Following the automatic extraction and filtration, a manual curation is performed to remove problematic sequences while preserving relevant sequences useful for phylogenetic studies. As a result of curation, ∼20% of the automatically filtered sequences have been removed from the database. To demonstrate how PHYMYCO-DB can be employed, we test a set of environmental Chytridiomycota sequences obtained from deep sea samples.ConclusionPHYMYCO-DB offers the tools necessary to: (i) extract high quality fungal sequences for each of the 5 fungal phyla, at all taxonomic levels, (ii) extract already performed alignments, to act as ‘reference alignments’, (iii) launch alignments of personal sequences along with stored data. A total of 9120 SSU rRNA and 672 EF1-α high-quality fungal sequences are now available.The PHYMYCO-DB is accessible through the URL http://phymycodb.genouest.org/.

Discovery of New Hydrothermal Activity and Chemosynthetic Fauna on the Central Indian Ridge at 18°–20°S

Indian Ocean hydrothermal vents are believed to represent a novel biogeographic province, and are host to many novel genera and families of animals, potentially indigenous to Indian Ocean hydrothermal systems. In particular, since its discovery in 2001, much attention has been paid to a so-called ‘scaly-foot’ gastropod because of its unique iron-sulfide-coated dermal sclerites and the chemosynthetic symbioses in its various tissues. Despite increasing interest in the faunal assemblages at Indian Ocean hydrothermal vents, only two hydrothermal vent fields have been investigated in the Indian Ocean. Here we report two newly discovered hydrothermal vent fields, the Dodo and Solitaire fields, which are located in the Central Indian Ridge (CIR) segments 16 and 15, respectively. Chemosynthetic faunal communities at the Dodo field are emaciated in size and composition. In contrast, at the Solitaire field, we observed faunal communities that potentially contained almost all genera found at CIR hydrothermal environments to date, and even identified previously unreported taxa. Moreover, a new morphotype of ‘scaly-foot’ gastropod has been found at the Solitaire field. The newly discovered ‘scaly-foot’ gastropod has similar morphological and anatomical features to the previously reported type that inhabits the Kairei field, and both types of ‘scaly-foot’ gastropods genetically belong to the same species according to analyses of their COI gene and nuclear SSU rRNA gene sequences. However, the new morphotype completely lacks an iron-sulfide coating on the sclerites, which had been believed to be a novel feature restricted to ‘scaly-foot’ gastropods. Our new findings at the two newly discovered hydrothermal vent sites provide important insights into the biodiversity and biogeography of vent-endemic ecosystems in the Indian Ocean.

A Second Species ofRhodachlya(Rhodachlyales, Rhodophyta) from Hawaii, with a Description ofR.hawaiianasp. nov.

Rhodachlya hawaiiana Kurihara, J.A. West, Conklin et A.R. Sherwood sp. nov. is described based on cultured material from the island of Hawaii as the second member of the genus Rhodachlya. The pit plug ultrastructure of this alga is characterized by the presence of inner and outer cap layers but lacking a cap membrane between the layers, which is a diagnostic feature of the order Rhodachlyales and the genus Rhodachlya. Morphologically, R. hawaiiana is distinctive from R. madagascarensis in vegetative cell dimensions, frequency of colorless hair cell formation, and spore germination pattern. Rhodachlya hawaiiana and R. madagascarensis are also distinguishable by their nuclear SSU rRNA gene sequence divergence (p-distance = 0.0064), which is comparable to other species-level divergences among members of the Nemaliophycidae.Rhodachlya hawaiiana Kurihara, J.A. West, Conklin et Sherwood sp. nov., décrite à partir de materiel cultivé provenant de l'île d'Hawaii, est la seconde espèce appartenant au genre Rhodachlya. L'ultrastructure des synapses de cette algue montre la présence d'une couche interne et d'une couche externe recouvrant le bouchon synaptique, sans membrane de revêtement entre les couches, ce qui est une des caractéristiques de l'ordre des Rhodachlyales. Morphologiquement R. hawaiiana diffère de R. madagascarensis par la taille de ses cellules végétatives, par la fréquence des cellules formant des poils hyalins et par le mode de germination des spores. Ils diffèrent aussi par la séquence de leur SSU rRNA avec une divergence (p-distance=0.0064) comparable à d'autres divergences entre espèces parmi les Nemaliophycidae.

Trematosphaeriaceae fam. nov. (Dothideomycetes, Ascomycota)

Abstract Trematosphaeriaceae fam. nov. is introduced to accommodate the genera Falciformispora, Halomassarina and Trematosphaeria. The main distinguishing characters of the family are medium-sized rounded ascomata with a papillate ostiole, a relatively wide, coriaceous peridium, cellular pseudoparaphyses and cylindro-clavate asci. The ascospores are two-celled or many celled, hyaline or brown. Phylogenetic analysis inferred from combined nuclear SSU and LSU rRNA and translation elongation factor 1-alpha (TEF-1-alpha) and second largest subunit of RNA polymerase (RPB2) datasets show that these genera form a strongly supported cluster within the Pleosporales. The type species of each genus is illustrated and briefly discussed. Asteromassaria pulchra has been included in the family in previous publications; however, since the type of the genus (A. macrospora) was not included in the phylogenetic analysis, the familial placement cannot be confirmed. Furthermore Asteromassaria pulchra did not cluster in Tremat...

Identification of group I introns within the SSU rDNA gene in species of Ceratocystiopsis and related taxa

During a recent phylogenetic study, group I introns were noted that interrupt the nuclear small subunit ribosomal RNA (SSU rDNA) gene in species of Ceratocystiopsis. Group I introns were found to be inserted at the following rDNA positions: S943, S989, and S1199. The introns have been characterized and phylogenetic analysis of the host gene and the corresponding intron data suggest that for S943 vertical transfer and frequent loss appear to be the most parsimonious explanation for the distribution of nuclear SSU rDNA introns among species of Ceratocystiopsis. The SSU rDNA data do suggest that a recent proposal of segregating the genus Ophiostoma sensu lato into Ophiostoma sensu stricto, Grosmannia, and Ceratocystiopsis has some merit but may need further amendments, as the SSU rDNA suggests that Ophiostoma s. str. may now represent a paraphyletic grouping.

Taxonomic and molecular studies of the family Sebdeniaceae (Sebdeniales, Rhodophyta): new species of Lesleigha gen. nov. and Crassitegula from Hawaii, east Asia and Lord Howe Island

The genus Lesleigha gen. nov., based on L. hawaiiensis sp. nov. from Oahu in the Hawaiian Islands, is characterized morphologically and anatomically and strongly supported as distinct from the other genera of the family Sebdeniaceae (Sebdenia and Crassitegula) primarily on the basis of mitochondrial COI-5P and nuclear SSU and LSU ribosomal DNA sequences. Characters distinguishing Lesleigha from Sebdenia include the repent, dorsiventral habit, nemathecial tetrasporangia, and irregularly cruciate tetrasporangial division pattern. Although these features are equally displayed by the recently described Crassitegula from Bermuda, that genus appears to differ from Lesleigha anatomically by its lack of a fusion cell subtending the gonimoblast, although in the absence of carposporophytes it is virtually necessary that DNA-sequence analyses be conducted before a distinction between Lesleigha and Crassitegula can be certain. Besides Lesleigha hawaiiensis, L. howensis sp. nov. is newly described from Lord Howe Island in the southern Pacific, and the Japanese and Korean Sebdenia yamadae is transferred to Lesleigha as L. yamadae, based on habit and anatomical conformity as well as DNA sequences. In addition, a new species of Crassitegula, C. imitans, is described from Lord Howe Island. The existence of further sebdenialean taxa is documented although not formally treated, indicating that substantial additional diversity most likely still awaits discovery in this reputedly species-poor order.