rDNA Phylogeny Research Articles

First isolation of Campylobacter vicugnae sp. nov. in humans suffering from gastroenteritis.

The present study describes the first isolation of a recently described Campylobacter species, Campylobacter vicugnae, in humans. The isolates were recovered by two independent French laboratories in 2020 and 2022 from a man and a woman suffering from gastroenteritis. Biochemical and growth characteristics, and electron microscopy for these two strains indicated that they belong to Campylobacter genus. 16S rDNA and GyrA-based phylogeny, as well as average nucleotide identity and in silico DNA-DNA Hybridization analyses revealed that both strains belong to the Campylobacter vicugnae species. Both isolates possess a complete cytolethal distending toxin (CDT) locus with cdtA, cdtB, and cdtC, and features of CDT activity were demonstrated in vitro with Caco-2 intestinal epithelial cells. Our data suggest that these two isolates of C. vicugnae were associated with gastroenteritis in humans and induced major cytopathogenic effects in vitro. C. vicugnae is likely to be a novel human pathogen, with a source of foodborne infection that needs to be determined.IMPORTANCECampylobacter species that display toxicity features are a worldwide public health issue. In clinical contexts, it is crucial to identify which isolate could be an urgent threat to a patient. Actual and widely used laboratory methods such as mass spectrometry or PCR may be flawed in the field of species identification. In contrast, the present study shows that next-generation sequencing allows to precisely identify isolates to species level that may have been omitted otherwise. Moreover, it helps to identify emerging species before they become a threat to human health. Recovery of a new Campylobacter species in human sample, such as the new species "Campylobacter vicugnae," is an important step for the identification of emerging pathogens posing threat to global health.

Morphology, morphogenesis, and molecular phylogeny of Holostichides (Holostichides) parachardezi nov. spec. (Ciliophora, Hypotrichia, Urostylida), a new soil ciliate from China

A new urostylid ciliate, Holostichides (Holostichides) parachardezi, collected from a Chinese tropical city, was studied using morphological and molecular methods. Diagnostic features of the new species include: size 140–180 × 30–60 μm in vivo; 25–43 macronuclear nodules; colourless cortical granules; three to six frontoterminal cirri; a midventral complex composed of seven to eleven cirral pairs and one midventral row of five to eleven cirri; four bipolar dorsal kineties and six to nine caudal cirri in four groups; and a terrestrial habitat. Its ontogenesis follows the typical Holostichides mode in that (1) the proximal portion of the parental adoral zone of membranelles is partly renewed and the opisthe’s oral primordium originates very close to the midventral complex; (2) the last anlage n generates the frontoterminal cirral row, and the midventral complex is formed from anlage IV to n − 1; and (3) both marginal rows and dorsal kinety anlagen develop within the parental rows. The present SSU rDNA phylogenies corroborated the monophyly of the genus Holostichides.

Phylogenomic diversity of archigregarine apicomplexans.

Gregarines are a large and diverse subgroup of Apicomplexa, a lineage of obligate animal symbionts including pathogens such as Plasmodium, the malaria parasite. Unlike Plasmodium, however, gregarines are poorly studied, despite the fact that as early-branching apicomplexans they are crucial to our understanding of the origin and evolution of all apicomplexans and their parasitic lifestyle. Exemplifying this, the earliest branch of gregarines, the archigregarines, are particularly poorly studied: around 80 species have been described from marine invertebrates, but almost all of them were assigned to a single genus, Selenidium. Most are known only from light micrographs and largely unresolved rDNA phylogenies, where they exhibit a great deal of sequence variation, and fall into four subclades. To resolve the relationships within archigregarines, we sequenced 12 single-cell transcriptomes from species representing all four known subclades, as well as one blastogregarine (which frequently branch with Selenidium). A 190-gene phylogenomic tree confirmed four maximally supported individual clades of archigregarines and blastogregarines. These clades are discrete and distantly related, and also correlate with host identity. We propose the establishment of three novel genera of archigregarines to reflect their phylogenetic diversity and host range, and nine novel species isolated from a range of marine invertebrates.

Antagonistic potential and biological control mechanisms of Pseudomonas strains against banded leaf and sheath blight disease of maize

Rhizoctonia solani, the causal agent of banded leaf and sheath blight (BL&SB), poses a significant threat to maize and various crops globally. The increasing concerns surrounding the environmental and health impacts of chemical fungicides have encouraged intensified concern in the development of biological control agents (BCAs) as eco-friendly alternatives. In this study, we explored the potential of 22 rhizobacteria strains (AS1–AS22) isolates, recovered from the grasslands of the Pithoragarh region in the Central Himalayas, as effective BCAs against BL&SB disease. Among these strains, two Pseudomonas isolates, AS19 and AS21, exhibited pronounced inhibition of fungal mycelium growth in vitro, with respective inhibition rates of 57.04% and 54.15% in cell cultures and 66.56% and 65.60% in cell-free culture filtrates. Additionally, both strains demonstrated effective suppression of sclerotium growth. The strains AS19 and AS21 were identified as Pseudomonas sp. by 16S rDNA phylogeny and deposited under accession numbers NAIMCC-B-02303 and NAIMCC-B-02304, respectively. Further investigations revealed the mechanisms of action of AS19 and AS21, demonstrating their ability to induce systemic resistance (ISR) and exhibit broad-spectrum antifungal activity against Alternaria triticina, Bipolaris sorokiniana, Rhizoctonia maydis, and Fusarium oxysporum f. sp. lentis. Pot trials demonstrated significant reductions in BL&SB disease incidence (DI) following foliar applications of AS19 and AS21, with reductions ranging from 25 to 38.33% compared to control treatments. Scanning electron microscopy revealed substantial degradation of fungal mycelium by the strains, accompanied by the production of hydrolytic enzymes. These findings suggest the potential of Pseudomonas strains AS19 and AS21 as promising BCAs against BL&SB and other fungal pathogens. However, further field trials are warranted to validate their efficacy under natural conditions and elucidate the specific bacterial metabolites responsible for inducing systemic resistance. This study contributes to the advancement of sustainable disease management strategies and emphasizes the potential of Pseudomonas strains AS19 and AS21 in combating BL&SB and other fungal diseases affecting agricultural crops.

Validation and redescription of Acanthamoeba terricola Pussard, 1964 (Amoebozoa: Acanthamoebidae)

Acanthamoeba castellanii (Douglas, 1930) Page, 1967 is the type species of a widespread genus of free-living amoebae, potentially pathogenic for humans and animals. The Neff strain is one of the most widely used in biological research, serving as a model for both A. castellanii and the whole genus in general. The Neff strain, isolated in California, closely resembles another strain found in France and originally described as a separate species, Acanthamoeba terricola Pussard, 1964, but both were successively synonymized with A. castellanii. Molecular sequence analysis has largely replaced morphological diagnosis for species identification in Acanthamoeba, and rDNA phylogenies show that the Neff strain forms a distinct lineage from that of the type strain of A. castellanii. In this study, we compared the type strain of A. terricola with the Neff strain and A. castellanii, and analysed the available molecular data including new sequences obtained from A. terricola. Here we provide molecular evidence to validate the species A. terricola. The Neff strain is therefore transferred to A. terricola and should no longer be considered as belonging to A. castellanii.

Three new species of arbuscular mycorrhizal fungi (Glomeromycota) and Acaulospora gedanensis revised.

Studies of the morphology and the 45S nuc rDNA phylogeny of three potentially undescribed arbuscular mycorrhizal fungi (phylum Glomeromycota) grown in cultures showed that one of these fungi is a new species of the genus Diversispora in the family Diversisporaceae; the other two fungi are new Scutellospora species in Scutellosporaceae. Diversispora vistulana sp. nov. came from maritime sand dunes of the Vistula Spit in northern Poland, and S. graeca sp. nov. and S. intraundulata sp. nov. originally inhabited the Mediterranean dunes of the Peloponnese Peninsula, Greece. In addition, the morphological description of spores of Acaulospora gedanensis, originally described in 1988, was emended based on newly found specimens, and the so far unknown phylogeny of this species was determined. The phylogenetic analyses of 45S sequences placed this species among Acaulospora species with atypical phenotypic and histochemical features of components of the two inner germinal walls.

New species of Dermoergasilus Ho & Do, 1982 (Copepoda: Cyclopoida: Ergasilidae) parasitizing endemic cichlid Paretroplus polyactis (Bleeker) in Madagascar.

Dermoergasilus madagascarensis n. sp. is described from the gills of Paretroplus polyactis, an endemic cichlid fish in Madagascar, using a combined morphological (light microscopy and SEM) and molecular approach (partial 18S rDNA, 28S rDNA, and COI sequences). The new species is characterized mainly by possessing: (i) roughly pentagonal cephalosome; (ii) antennal endopodal segments covered with slightly inflated membrane; (iii) maxillule bearing 2 equally long outer setae and a minute inner seta; (iv) interpodal sternites of swimming legs ornamented with 3–4 rows of spinules; (v) genital segment and first abdominal somite both barrel-shaped; and (vi) a caudal ramus projecting into a digitiform process with inconspicuous terminal seta and bearing 3 terminal setae. The obtained DNA sequences of Malagasy species represent the first molecular data for species of Dermoergasilus. The 28S rDNA phylogeny showed the affiliation of D. madagascarensis n. sp. to Ergasilidae and its sister relationship with cosmopolitan Ergasilus sieboldi von Nordmann, 1832. The first checklist for all species of Dermoergasilus is provided.

Integrative taxonomic study of mononchid nematodes from riparian habitats in Bulgaria. I. Genera Mononchus Bastian, 1865 and Coomansus Jairajpuri & Khan, 1977 with the description of Mononchuspseudoaquaticus sp. nov. and a key to the species of Mononchus.

The species diversity of the genera Mononchus Bastian, 1865 and Coomansus Jairajpuri & Khan, 1977 was assessed in a study of the mononchid nematodes from a wide range of riparian habitats in Bulgaria. Four species were identified based on morphological and morphometric data: Coomansusparvus (de Man, 1880), Mononchustruncatus Bastian, 1865, Mononchuspseudoaquaticus sp. nov., and Mononchus sp. The first three species were characterised both morphologically and molecularly (18S and 28S rRNA gene sequences) and the integration of these data and phylogenetic analyses provided support for their distinct species status. This paper provides detailed descriptions, morphometric data for multiple species populations, drawings and photomicrographs, and the first taxonomically verified sequences for C.parvus (n = 6), M.truncatus (sensu stricto) (n = 4) and M.pseudoaquaticus sp. nov. (n = 3). Comparative sequence and phylogenetic analyses suggested that the utility of the 18S rRNA gene for species delimitation is rather limited at least for some species complexes within the genus Mononchus. At the generic and suprageneric level, the 18S and 28S rDNA phylogenies both recovered the three genera represented by two or more species (Mononchus, Mylonchulus, and Parkellus) as monophyletic with strong support, the Mononchidae as paraphyletic, the Anatonchidae as monophyletic, and there was no support for a sister-group relationship between Mylonchulus and Mononchus. A key to the species of Mononchus is provided to facilitate the identification of the currently recognised 31 species.

Dispersal and invasive stages of Urospora eugregarines (Apicomplexa) from brown bodies of a polychaete host

Urosporid eugregarines (Apicomplexa: Urosporidae) are unicellular eukaryotic parasites inhabiting the coelom or the intestine of marine invertebrates such as annelids, molluscs, nemerteans, and echinoderms. Despite the availability of published morphological and phylogenetical analyses of coelomic gregarines, their long-term survival in the host body cavity and dispersal routes into the marine environment remain unclear. Here, we focus on Urospora gametocysts and oocysts with sporozoites, which were found viable inside the so-called brown bodies floating in the body cavity of the polychaete Travisia forbesii. Brown bodies form as a result of host defence where coelomocytes encapsulate dead host cells and foreign objects including potential pathogens. We hypothesise the long-term persistence of Urospora eugregarines in brown bodies through evasion of the host immunity and outline possible pathways for their egress into the marine environment, applicable as dispersal routes for other parasites as well. Unique features revealed by detailed ultrastructural analysis of detected eugregarine stages include asynchronous sporogony, a massive sporozoite secretion apparatus, as well as the presence of free (possibly autoinfective) sporozoites within the gametocyst. The assignment to the genus Urospora and the complete identity with U. ovalis and U. travisiae were confirmed by analysing 18S rDNA sequences obtained from isolated gametocysts. The 18S rDNA phylogeny confirmed the affiliation of Urosporidae to Lecudinoidea and the grouping of all Urospora sequences with Difficilina from nemerteans and environmental sequences from the Artic region. We also enriched the Apicomplexa set by partial 28S rDNA sequences of two Urospora species enabling more complex phylogenetic analyses prospectively.

Taxonomy and phylogeny of Chaetoceros species of the section Stenocincta (Bacillariophyceae), with emendation of C. affinis and C. willei and description of three new species

ABSTRACT Species of Chaetoceros sect. Stenocincta are frequently observed in marine phytoplankton. To study species diversity within the section Stenocincta, monoclonal strains were established from Chinese coastal waters and Norwegian Sea. Following detailed morphological observations and molecular evidence inferred from nucleus-encoded large subunit ribosomal DNA, the descriptions of C. affinis and C. willei are emended based on isolates from their respective type localities. Additionally, three new species are described. Chaetoceros donghaiensis sp. nov. is characterized by short straight chains, with thin setae only, and terminal setae that tend to cross distally. Chaetoceros forceps sp. nov. is unique by its thick terminal setae, each with an inflation near the end, with each pair forming a V-shape, resembling forceps. Chaetoceros lepidus sp. nov. is characterized by short, straight chains, narrowly elliptical valve faces, setae all located in the apical plane, and arched intercalary setae in opposite directions to the chain axis in broad girdle views. Three other distinct clades, which may also represent new species, were discerned in the LSU rDNA phylogeny, but more morphological characters are needed before formal proposals can be made. These species/clades formed a well-supported monophyletic lineage, supporting the current circumscription of section Stenocincta. This section is characterized by colonies in straight chains, cells with one chloroplast only, narrow lanceolate apertures, and terminal setae generally thicker than intercalary ones or both similar and thin. However, in C. diversus the terminal setae are thin and distinctly thicker pairs of intercalary setae are usual.

Efficiency of Lactiplantibacillus plantarum JT-PN39 and Paenibacillus motobuensis JT-A29 for Fermented Coffee Applications and Fermented Coffee Characteristics.

To develop a process for low-cost and ecologically friendly coffee fermentation, civet gut bacteria were isolated and screened to be used for fermentation. Among 223 isolates from civet feces, two bacteria exhibited strong protease, amylase, lipase, pectinase, and cellulase activities. By analyzing 16S rDNA phylogeny, those bacteria were identified to be Lactiplantibacillus plantarum JT-PN39 (LP) and Paenibacillus motobuensis JT-A29 (PM), where their potency (pure or mixed bacterial culture) for fermenting 5 L of arabica parchment coffee in 48-72 h was further determined. To characterize the role of bacteria in coffee fermentation, growth and pH were also determined. For mixed starter culture conditions, the growth of PM was not detected after 36 h of fermentation due to the low acid conditions generated by LP. Coffee quality was evaluated using a cupping test, and LP-fermented coffee expressed a higher cupping score, with a main fruity and sour flavor, and a dominant caramel-honey-like aroma. Antioxidant and anti-foodborne pathogenic bacteria activity, including total phenolic compounds of PM and LP fermented coffee extracts, was significantly higher than those of ordinary coffee. In addition, LP-fermented coffee expressed the highest antibacterial and antioxidant activities among the fermented coffee. The toxicity test was examined in the murine macrophage RAW 264.7 cell, and all fermented coffee revealed 80-90% cell variability, which means that the fermentation process does not generate any toxicity. In addition, qualifications of non-volatile and volatile compounds in fermented coffee were examined by LC-MS and GC-MS to discriminate the bacterial role during the process by PCA plot. The flavors of fermented coffee, including volatile and non-volatile compounds, were totally different between the non-fermented and fermented conditions. Moreover, the PCA plot showed slightly different flavors among fermentations with different starter cultures. For both the cupping test and biological activities, this study suggests that LP has potential for health benefits in coffee fermentation.

Molecular phylogenetics of sessile Dolium sedentarium, a petalomonad euglenid.

The euglenids are a species-rich group of flagellates with varying modes of nutrition that can be found in diverse habitats. Phagotrophic members of this group gave rise to phototrophs and hold the key to understanding the evolution of euglenids as a whole, including the evolution of complex morphological characters like the euglenid pellicle. Yet to understand the evolution of these characters, a comprehensive sampling of molecular data is needed to correlate morphological and molecular data, and to estimate a basic phylogenetic backbone of the group. While the availability of SSU rDNA and, more recently, multigene data from phagotrophic euglenids has improved, several "orphan" taxa remain without any molecular data whatsoever. Dolium sedentarium is one such taxon: It is a rarely-observed phagotrophic euglenid that inhabits tropical benthic environments and is one of few known sessile euglenids. Based on morphological characters, it has been thought of as part of the earliest branch of euglenids, the Petalomonadida. We report the first molecular sequencing data for Dolium using single-cell transcriptomics, adding another small piece in the puzzle of euglenid evolution. Both SSU rDNA and multigene phylogenies confirm it as a solitary branch within Petalomonadida.

The Occurrence of the Strongylid Nematodes, Kalicephalus viparae viparae (Nematoda: Diaphanocephalidae), in Viper Snakes, Macrovipera lebetina (Reptilia: Viperidae), Southwestern Iran.

ancylostomatid Kalicephalus spp. is the common parasitic intestinal nematode of reptiles. West-Asian blunt-nosed viper is a venomous snake found in extensive areas of Iran. From June to September 2017, two dead viper snakes were referred to a parasitology laboratory and examined for intestinal parasites. Several white elongated roundworms were collected and fixed to identify under light and scanning electron microscopes (SEM) based on morphological and molecular characteristics. For the molecular survey, some parts of the identified worms were extracted and the ITS of nuclear ribosomal DNA (rDNA) was amplified by polymerase chain reaction (PCR). Five roundworms were found in one snake and three worms with similar morphological characteristics in another one. All the collected female hookworms were taxonomically identified as Kalicephalus viperae viperae. The SEM findings showed the head was small and had three dorsal, ventral, and middle circumoral papillae with a spike-like process on the median papilla of K. viperae. Moreover, the buccal capsule was bivalvular and included two lateral valves consisting of several chitonid pieces. The tail of the female worm was slim and long with a blunt end and had a terminal spike at its end. In the molecular survey, the ITS of rDNA amplified at about 850 bp was identified as K. viperae. The ITS gene rDNA phylogeny analysis of the K. viperae sequence showed that the isolated species had high similarity to Ancylostoma species from around the world and is close to Ancylostoma braziliense with 88% discrepancies in the phylogenetic tree. The morphological characteristics and a large part of K. viperea viperea rDNA nucleotide sequence were reported in viper snakes for the first time in the world and in Iran.

Characterisation and Cultivation of New Lineages of Colponemids, a Critical Assemblage for Inferring Alveolate Evolution

There are several alveolate groups outside the well-studied trio – ciliates, dinoflagellates, and apicomplexans – that are crucial for understanding the evolution of this major taxon. One such assemblage is the “colponemids”, which are eukaryotrophic biflagellates, usually with a ventral groove associated with the posterior flagellum. Previous phylogenetic studies show colponemids forming up to three distinct deep branches within alveolates (e.g. sister groups to Myzozoa or all other alveolates). We have developed dieukaryotic (predator–prey) cultures of four colponemid isolates. One represents the first stable culture of the halophile Palustrimonas (feeding on Pharyngomonas), while SSU rDNA phylogenies show the other isolates as two distinct new lineages. Neocolponema saponarium gen. et sp. nov. is a swimming alkaliphile with a large groove, which feeds on a kinetoplastid. Loeffela hirca gen. et sp. nov. is halophilic, has a subtle groove, usually moves along surfaces, and feeds on Pharyngomonas and Percolomonas. Prey capture in both new genera is raptorial, involves a specialized structure/region to the right of the proximal posterior flagellum, and presumed extrusomes. The relationships amongst Myzozoa, ciliates, and the (now) five described colponemid clades are unresolved, signaling that colponemid diversity represents both a challenge and important resource for tracing deep alveolate evolution.

Morpho-molecular analysis of podolampadacean dinoflagellates (Dinophyceae), with the description of two new genera

ABSTRACT Sequences were obtained for 58 podolampadacean single cells from France, Reunion Island (French territories) and Japan (6 SSU rDNA only, 40 SSU+LSU and 12 LSU only). The sequenced taxa belong to five of the eight described genera: Podolampas, Blepharocysta, Lissodinium, Gaarderiella and Mysticella. Two new genera, Alatosphaera and Pseudalatosphaera, were erected to accommodate ‘Blepharocysta’ hermosillae and ‘Blepharocysta’ denticulata. Most genera are well supported by concatenated LSU–SSU rDNA phylogenies, with the least support for Lissodinium. Metabarcoding of podolampadaceans using the V4 region of SSU rDNA showed a resolution too low to discriminate genera or species. Roscoffia and Cabra are here considered podolampadaceans, whilst Lessardia is considered to belong in a separate family. The relationship of Rhinodinium to the Podolampadaceae needs further study. Desmoschisis was recorded for the first time in Alatosphaera and Pseudalatosphaera. Several ribotypes need further study to attribute a species name to them.

Taxonomic changes in the Lomentariaceae (Rhodymeniales, Rhodophyta): Yendoa gen. nov. and Ceratodictyon sanctae-crucis sp. nov.

ABSTRACT The Lomentariaceae, previously treated as subfamily Lomentarioideae in the family Champiaceae, is one of the six families currently classified in the Rhodymeniales. Relationships within the family are not well-established, and new genera have been segregated from Lomentaria, a notoriously polyphyletic taxon as currently circumscribed. The lack of access to molecular data of type specimens has limited the taxonomic clarifications within the Lomentariaceae. Using new collections from Brazil, historical collections and data available in GenBank, we generated rbcL and COI-5P phylogenies of the Lomentariaceae, and we used species delimitation methods to assess the species-level diversity among sequences. A nuclear LSU rDNA phylogeny, although less representative in number of taxa, confirmed our findings. Our results recovered Ceratodictyon and Semnocarpa as monophyletic, whereas Lomentaria was polyphyletic. Integrating phylogenetic analyses, analyses of genetic variance, and morphological analyses, we revealed a new species, Ceratodictyon sanctae-crucis sp. nov., collected on the coast of Bahia (northeastern Brazil). Having included a newly generated sequence of the holotype of Lomentaria sinensis, a heterotypic synonym of L. hakodatensis, and a sequence from a sample collected near the type locality of L. hakodatensis, we propose the new genus Yendoa gen. nov. to accommodate this species. Our results support a more phylogenetically coherent taxonomic scheme for the Lomentariaceae, which now includes only monophyletic genera.

Hidden diversity in Selenastraceae (Sphaeropleales, Chlorophyceae): Molecular phylogeny revealed a nannoplanktonic species, with the description of Viridiparva madeirensis gen. et sp. nov.

The simple morphology of the members of the family Selenastraceae, common in freshwater phytoplankton, has led to misidentifications. But the use of molecular tools is untangling their phylogeny and unveiling new genera and species hidden under the same morphotype or overlooked by microscopic analysis. Here we propose a description of Viridiparva madeirensis gen. et sp. nov., a small Selenastraceae member, based on the study of three strains by light, scanning and transmission microscopy and 18S rDNA and rbcL phylogenies. The phylogenetic analyses by 18S rDNA and rbcL show, respectively, that the closest relatives to Viridiparva madeirensis are Monoraphidium dybowskii and Raphidocelis microscopica, but with no or low statistical support. V. madeirensis is smaller than M. dybowski and has no cell wall incrustations typical for Raphidocelis. Thus, phylogeny and morphological analyses indicate a novel lineage within Selenastraceae. Furthermore, also reinforce the necessary revision of the genera within Selenastraceae, as Monoraphidium and Raphidocelis. Therefore study contributes to clarify the phylogeny and taxonomy of the family and add genetic sequences of neglected nanophytoplankton to GenBank, including one strain with known potential for biodiesel production.

Phylogeny and fatty acid profiles of Aliinostoc vietnamicum sp. nov. (cyanobacteria) from the soils of Vietnam.

A new cyanobacterial species of Aliinostoc, A. vietnamicum sp. nov., is recorded in the tropical forest soil from the Cát Tiên National Park, Vietnam. The analysis is based on morphological characters, 16S rDNA phylogeny, ITS secondary structure, and fatty acid composition analysis. Aliinostoc vietnamicum differed from the other species of the genus by the size and shape of vegetative cells, size of akinetes and heterocytes, and presence of granular polyphosphate inclusions in vegetative cells. The evolutionary distance matrix based on the 16S rRNA gene shared 96.2-98.2% similarities with other Aliinostoc sequences. The phylogeny inferred by maximum likelihood and Bayesian inference placed A. vietnamicum in the Aliinostoc clade, within the Nostocaceae. For the first time, fatty acid composition analysis was obtained for a member of the genus Aliinostoc with cultivation time experiments. α-linolenic (27.54-37.75%), palmitic (13.87-22.65%), and stearic (10.08-20.27%) acids were the dominant fatty acids when cultured during the exponential growth phase, as well as during stationary. This is the first finding of a strain with such a high content of stearic acid among cyanobacteria with Nostoc-like morphology.

Ultrastructure and phylogeny of Parvodinium cunningtonii comb. nov. (syn. Peridiniopsis cunningtonii) and description of P. cunningtonii var. inerme var. nov. (Peridiniopsidaceae, Dinophyceae)

Two strains of peridinioids were isolated from a flooded stream near Aveiro, central Portugal, and examined by light microscopy, scanning electron microscopy and serial-section transmission electron microscopy. The two strains showed the same tabulation and cell shape as Peridiniopsis cunningtonii. One of the strains had lightly reticulated plates and spines in most hypothecal plates, matching the features of typical P. cunningtonii. The other strain showed smooth plates and consistently lacked spines in the apiculate hypotheca. The strains were similar in fine structure and had a central pyrenoid with a starch sheath and perforated by cytoplasmic channels. Details of the flagellar apparatus matched those known from Parvodinium, as did the remarkably long microtubular strand leading to an extruded peduncle that was visible in serial sections. Phylogenetic analyses based on partial LSU rDNA and the concatenated ribosomal operon placed the strain with the smooth hypotheca in a clade with Parvodinium species. The two strains grouped as closely related sister taxa in the partial LSU rDNA phylogeny. A new combination is proposed, Parvodinium cunningtonii comb. nov. and a new variety, Parvodinium cunningtonii var. inerme var. nov., is described.

Siamcapillus rubidus gen. et sp. nov. (Oculatellaceae), a novel filamentous cyanobacterium from Thailand based on molecular and morphological analyses

Cyanobacterial diversity has been extensively studied; however, scant knowledge exists concerning genetic data and higher accuracy for tropical cyanobacterial diversity. In particular, the existence of unnamed monophyletic genera within the Oculatellaceae requires further investigation. Here, two novel strains (NUACC13 and NUACC14) were isolated from a cyanobacterial mat covering border soil of a small freshwater pond in Phitsanulok Province, Thailand. A polyphasic approach combining genetic (16S rDNA and rpoC1 gene phylogenies, evolutionary distance and ITS secondary structures) and morphological information was applied to evaluate the taxonomic status of these novel strains. All phylogenetic analyses of 16S rDNA and rpoC1 gene sequences placed our strains within the Oculatellaceae, strongly supporting a novel monophyletic clade that did not belong to other known Oculatellaceae genera. The 16S rDNA sequence similarity (<96.2%) values among the closest described genera also supported the novelty of our strains. The hypothetical secondary structures (D1–D1′, Box-B, V2 and V3 helices) of the ITS region confirmed the uniqueness of our strains, indicating differences from the related genera. Morphological features of the novel strains differed from the phylogenetically closest taxa by size and color of filament and vegetative cell and the presence of a frayed sheath. Considering all the results, we herein described our strains as the novel genus Siamcapillus gen. nov. in the Oculatellaceae with the type species S. rubidus sp. nov.