ASSESSING THE RELATIONSHIPS OF AUTOSPORIC AND ZOOSPORIC CHLOROCOCCALEAN GREEN ALGAE WITH 18S rDNA SEQUENCE DATA1

We examined the relationships of autosporic and zoosporic taxa in the Chlorococcales by analyzing available complete nuclear-encoded small-subunit (18S) rRNA gene sequences along with two new sequences from Hydrodictyon reticulatum (L.) Lagerh. and Neochloris vigenis Archibald. Some autosporic taxa grouped with the coenobial hydrodictyacean algae and related unicellular organisms having directly opposed basal bodies. These include Scenedesmus obliquus (Turp.) Kütz. and Chlorella fusca var. vacuolata Shihira et Krauss. Other autosporic organisms, including Chlorella kessleri Fott et Novakova, C. minutissima Fott et Novakova, C. pro-tothecoides Krug., C. vulgaris Beij., Nanochlorum eucaryotum Wilhelm, Eisenbeis, Wild, et Zahn, and Prototheca wickerhamii Soneda et Tubaki, form a separate group. Of the zoosporic taxa examined, this group would appear to have the greatest affinity to organisms having a counterclockwise displacement of basal bodies, the Pleurastrophyceae. Beyond the fact that Ankistrodesmus stipitatus (=A. falcatus var. stipitatus (Chodat) Lemm.) does not group with the latter organisms, its position remains in doubt. None of the autosporic taxa appear to be closely related to chlorophycean organisms possessing a clockwise basal body displacement.     

RELATIONSHIP BETWEEN PRESENCE OF A MOTHER CELL WALL AND SPECIATION IN THE UNICELLULAR MICROALGA NANNOCHLORIS (CHLOROPHYTA)1

The cell division mechanisms of seven strains from six species of Nannochloris Naumann were analyzed and compared with those of three species of Chlorella Beijerinck and Trebouxia erici Ahmadjian using differential interference microscopy and fluorescence microscopy. Nannochloris bacillaris Naumann divides by binary fission and N. coccoides Naumann divides by budding. Distinct triangular spaces or mother cell walls were found in the dividing autosporangia of the other five strains from four species of Nannochloris, three species of Chlorella, and T. erici. In an attempt to infer an evolutionary relationship between nonautosporic and autosporic species of Nannochloris, we constructed a phylogenetic tree of the actin genes using seven strains from six species of Nannochloris, three species of Chlorella, and T. erici. Nannochloris species were polyphyletic in the Trebouxiophyceae group. Two nonautosporic species of N. bacillaris and N. coccoides were monophyletic and positioned distally. Moreover, to determine their phylogenetic position within the Trebouxiophyceae, we constructed phylogenetic tree of 18S rRNA genes adding other species of Trebouxiophyceae. Nannochloris species were polyphyletic in the Trebouxiophyceae and appeared in two different lineages, a Chlorella–Nannochloris group and a Trebouxia–Choricystis group. The nonautosporic species, N. bacillaris and N. coccoides, and three autosporic species of Nannochloris belonged to the Chlorella–Nannochloris group. Nannochloris bacillaris and N. coccoides were also monophyletic and positioned distally in the phylogenetic tree of 18S rRNA genes. These results suggest that autosporulation is the ancestral mode of cell division in Nannochloris and that nonautosporulative mechanisms, such as binary fission and budding, evolved secondarily.     

Genome-based reclassification of the genus Meiothermus along with the proposal of a new genus Allomeiothermus gen. nov

Phylogenomic analyses were performed on the nine species of the genus Meiothermus and four species of the genus Calidithermus. Phylogenetic analysis, low values of genomic relatedness indices and functional diversity analysis indicated that Meiothermus silvanus should not be classified within the clades for Meiothermus and Calidithermus but instead be reclassified as a new genus, for which we propose the name Allomeiothermus gen. nov., with Allomeiothermus silvanus comb. nov. as type species. In addition, the species Meiothermus cateniformans Zhang et al. (Int J Syst Evol Microbial 60:840–844, 2010) should also be reclassified as a later heterotypic synonym of Meiothermus taiwanensis Chen et al. (Int J Syst Evol Microbiol 52:1647–1654, 2002) emend. Raposo et al. (2019). This reclassification is based on the high genomic relatedness indices (98.8% ANI; 90.2% dDDH; 99% AAI) that are above the threshold values necessary for defining a new species, as well as on the observation of overlapping functions on Principal Coordinate Analysis plot generated from Clusters of Orthologous Genes.

     

The yeast genus Yarrowia gen. nov.

The ascigerous teleomorph of Candida lipolytica (Harrison) Diddens et Lodder, previously classified as Endomycopsis lipolytica Wickerham et al. and as Saccharomycopsis lipolytica (Wickerham et al.) Yarrow, has been assigned to the new genus Yarrowia. Yarrowia lipolytica (Wickerham et al.) comb. nov. is the type species for the genus.The remaining species of Saccharomycopsis are revised.     

Macrosiagon deuvei n. sp. (Coleoptera: Ripiphoridae) from the French Eocene amber

Macrosiagon deuvei n. sp., the second fossil representative of this extant genus of Ripiphoridae: Ripiphorinae: Macrosiagonini is described from the lowermost Eocene amber of Oise (France). The new species is compared with the extant species of the genus. Taxonomic position of other two fossil representatives of the family described from France by Perrichot et al. (2004) is discussed. The genus Paleoripiphorus Perrichot et al. 2004 is tentatively transferred from Ripiphorinae to Ripidiinae.     

PIGMENT AND CYTOLOGICAL EVIDENCE FOR RECLASSIFICATION OF NANNOCHLORIS OCULATA AND MONALIANTUS SALINA IN THE EUSTIGMATOPHYCEAE1

Nannochloris oculata Droop and Monallantus salina Bourrelly produce similar chloroplast pigments and show alike ultrastructural features separating them from the Chlorophyceae and Xanthophyceae, respectively, and linking them to the Eustigmatophyceae. It is proposed that N. oculata should be removed from the chlorophyceaen genus Nannochloris and transferred to a new taxon of coccoid eustigmatophytes containing the closely related M. salina: nomenclatural revisions are required for both strains.     

Rockin' in rhythm,growth dynamics of the peat moss Sphagnum

The genus Sphagnum is an essential component in the formation and maintenance of high latitude peatlands, bogs and mires. The species grows in dense, extended mats of agglomerated shoots that allow it to retain water necessary for its growth. These mats are partly responsible for maintaining the right conditions for other species in these wetlands to thrive. In this issue of Physiologia Plantarum, Mironov et al. (2020) monitored the growth of Sphagnum riparium for a period of 4 years and revealed three distinct growth rhythms: a seasonal temperature dependent, a circalunar and a third one, synchronized with the circalunar. This synchronised nature of Sphagnum growth could contribute to its position as a key species in the maintenance of peatlands.     

Phylogenetic relationships of the green algeVolvox carteri deduced from small-subunit ribosomal RNA comparisons

Summary The 1788-nucleotide sequence of the small-subunit ribosomal RNA (srRNA) coding region from the chlorophyteVolvox carteri was determined. The secondary structure bears features typical of the universal model of srRNA, including about 40 helices and a division into four domains. Phylogenetic relationships to 17 other eukaryotes, including two other chlorophytes, were explored by comparing srRNA sequences. Similarity values and the inspection of phylogenetic trees derived by distance matrix methods revealed a close relationship betweenV. carteri andChlamydomonas reinhardtii. The results are consistent with the view that these Volvocales, and the third green alga,Nanochlorum eucaryotum, are more closely related to higher plants than to any other major eukaryotic group, but constitute a distinct lineage that has long been separated from the line leading to the higher plants.     

Description de Artareites landii nov. (Ammonoidea) du Barrémien supérieur de Majastre (Sud-Est de la France) et discussion sur les Helicancylidae Hyatt, 1894

In the Majastre area (Alpes-de-Haute-Provence, South-Eastern France), the hemipelagic domain of the Lower Cretaceous is exposed to the favour of the “Décrochement du Poil”. This palaeogeographical and paleotectonic position allowed the harvest of a diversified ammonite-fauna in the level with “small Barremites”. It is precisely dated here for the first time, and takes place between the base of the Barremense subzone and the base the Breistrofferi biohorizon of the Vandenheckei biozone (base of the Upper Barremian). Within this fauna, Artareites landii nov. sp. is considered here as a possible descendant of the genus Dissimilites Sarkar due to its characteristics and stratigraphic position. The genus Artareites nov. gen. is certainly an important milestone of the Helicancylidae towards the Toxoceratoides genus morphology. In this case, in agreement with the morphological, ontogenical, stratigraphical and paleobiogeographical parameters, some North American species could be considered as potential intermediate. Due to their characteristics and their joint origin, genus of small size included in the Helicancylidae represent a coherent set with the rank of a family, and is independent of the Ancyloceratidae. Its content is revised and limited to the genus phyletically associated around the main axis of Acrioceras-Dissimilites-Artareites nov. gen. and Toxoceratoides-Helicancylus, whose elements are connected by a number of forms. In this case, Monodites nov. gen. is created for the Hauterivian and Lower Barremian very specific forms Monodites crevolai (Vermeulen et al.) and Monodites trumpyi (Kakabadze et Thieuloy) which does not seem to be integrated in the taxa already recognized in the literature. The family Monoditidae nov. fam. is proposed to mark this uniqueness.     

EVOLUTIONARY ORIGIN OF GLOEOMONAS (VOLVOCALES,CHLOROPHYCEAE), BASED ON ULTRASTRUCTURE OF CHLOROPLASTS AND MOLECULAR PHYLOGENY1

Gloeomonas is a peculiar unicellular volvocalean genus because it lacks pyrenoids in the chloroplasts under the light microscope and has two flagellar bases that are remote from each other. However, ultrastructural features of chloroplasts are very limited, and no molecular phylogenetic analyses have been carried out in Gloeomonas. In this study, we observed ultrastructural features of chloroplasts of three species of Gloeomonas and Chloromonas rubrifilum (Korshikov ex Pascher) Pröschold, B. Marin, U. Schlösser et Melkonian SAG 3.85, and phylogenetic analyses were carried out based on the combined data set from 18S rRNA, ATP synthase beta‐subunit, and P700 chl a–apoprotein A2 gene sequences to deduce the natural phylogenetic positions of the genus Gloeomonas. The present EM demonstrated that the chloroplasts of the three Gloeomonas species and C. rubrifilum SAG 3.85 did not have typical pyrenoids with associated starch grains, but they possessed pyrenoid matrices that protruded interiorly within the stroma regions of the chloroplast. The pyrenoid matrices were large and broad in C. rubrifilum, whereas those of the three Gloeomonas species were recognized in only the small protruded regions of the chloroplast lobes. The present multigene phylogenetic analyses resolved that the three species of Gloeomonas belong to the Chloromonas lineage or Chloromonadinia of the Volvocales, and Chloromonas insignis (Anakhin) Gerloff et H. Ettl NIES‐447 and C. rubrifilum SAG 3.85, both of which have pyrenoids without associated starch grains, were positioned basally to the clade composed of the three species of Gloeomonas. Therefore, Gloeomonas might have evolved from such a Chloromonas species through reduction in pyrenoid matrix size within the chloroplast and by separating their two flagellar bases.     

New Species of Spirotrichonympha from Reticulitermes and the Relationships Among Genera in Spirotrichonymphea (Parabasalia)

Spirotrichonymphea is a class of hypermastigote parabasalids defined by their spiral rows of many flagella. They are obligate hindgut symbionts of lower termites. Despite more than 100 yr of morphological and ultrastructural study, the group remains poorly characterised by molecular data and the phylogenetic positions and taxonomic validity of most genera remain in question. The genus Spirotrichonympha has been reported to inhabit several termite genera, including Reticulitermes, Coptotermes, and Hodotermopsis. The type species for this genus, Spirotrichonympha flagellata, was described from Reticulitermes lucifugus but no molecular data are yet available for this species. In this study, three new Spirotrichonympha species are described from three species of Reticulitermes. Their molecular phylogenetic position indicates that the genus is not monophyletic, as Spirotrichonympha species from Coptotermes, Paraneotermes, and Hodotermopsis branch separately. In contrast, the genus Holomastigotoides is monophyletic, as demonstrated using new sequences from Holomastigotoides species. The presence of Holomastigotoides in Prorhinotermes and the distinct phylogenetic positions of Spirotrichonympha from Reticulitermes and Coptotermes are consistent with a previously proposed symbiont fauna replacement in the ancestor of Reticulitermes.     

PHYLOGENETIC POSITION OF ATTHEYA LONGICORNIS AND ATTHEYA SEPTENTRIONALIS (BACILLARIOPHYTA)1

The phylogenetic position of diatoms belonging to the genus Attheya is presently under debate. Species belonging to this genus have been placed in the subclasses Chaetocerotophycidae and Biddulphiophycidae, but published phylogenetic trees based on 18S rDNA, morphology, and sexual reproduction indicate that this group of diatoms may be a sister group of the pennates. To clarify the position of Attheya, we studied the morphology, 18S rDNA, 16S rDNA of the chloroplasts, the rbcL large subunit (LSU) sequences of the chloroplasts, and the sterol composition of three different strains of Attheya septentrionalis (Østrup) R. M. Crawford and one strain of Attheya longicornis R. M. Crawford et C. Gardner. These data were compared with data from more than 100 other diatom species, covering the whole phylogenetic tree, with special emphasis on species belonging to the genera that have been suggested to be related to the genus Attheya. All data suggest that the investigated Attheya species form a separate group of diatoms, and there is no indication that they belong to either the Chaetocerotophycidae or the Biddulphiophycidae. Despite applying these various approaches, we were unable to determine the exact phylogenetic position of the investigated Attheya species within the diatoms.     

CRYPTOPERIDINIOPSIS BRODYI GEN. ET SP. NOV. (DINOPHYCEAE), A SMALL LIGHTLY ARMORED DINOFLAGELLATE IN THE PFIESTERIACEAE1

A new genus and species of heterotrophic dinoflagellate, Cryptoperidiniopsis brodyi gen. et sp. nov., are described. This new species commonly occurs in estuaries from Florida to Maryland, and is often associated with Pfiesteria piscicida Steidinger et Burkholder, Pseudopfiesteria shumwayae (Glasgow et Burkholder) Litaker et al., and Karlodinium veneficum (Ballantine) J. Larsen, as well as other small (<20 μm) heterotrophic and mixotrophic dinoflagellates. C. brodyi gen. et sp. nov. feeds myzocytotically on pigmented microalgae and other microorganisms. The genus and species have the enhanced Kofoidian plate formula of Po, cp, X, 5′, 0a, 6″, 6c, PC, 5+s, 5″′, 0p, and 2″″ and are assigned to the order Peridiniales and the family Pfiesteriaceae. Because the Pfiesteriaceae comprise small species and are difficult to differentiate by light microscopy, C. brodyi gen. et sp. nov. can be easily misidentified.     

Proposal of Microsquama subgen. nov. for Nephroselmis pyriformis (Carter) Ettl (Nephroselmidophyceae,Chlorophyta)

A new subgenus, Microsquama, is proposed for Nephroselmis pyriformis based on its phylogenetic position and some ultrastructural characters, such as the absence of large stellate scales. Other species of the genus are classified in the subgenus Nephroselmis.     

Speciation and chromosomal evolution of the Palearctic species of chironomids of the genus Sergentia Kieffer (Diptera, Chironomidae): Divergence of the Karyotypes of S. baueri Wülker et al., 1999, S. prima Proviz et al., 1997, S. electa Proviz et al., 1999 and their relationship with the endemic species from Baikal lake

The banding structures of chromosomes of three Palearctic species of chironomids of the genus Sergentia Kieffer, 1922 from the Irkutsk reservoir were comparatively analyzed: S. baueri Wülker et al., 1999 (2n = 8), S. prima Proviz et al., 1997 (2n = 8), and S. electa Proviz et al., 1999 (2n = 6). The S. baueri karyotype was taken as a standard in chromosome mapping. It was established that in contrast to S. baueri and S. prima the S. electa karyotype was formed due to a complex translocation: transfer of chromosome IV in the median part of chromosome III. The sequences of chromosome I bands were found to be completely homologous in all Palearctic species and in S. rara Proviz et al., 1999 (2n = 8) taken as the original species in the group of Baikalian endemics. In both groups, seven homozygous inversions were detected, of which the common one is the inversion in chromosome III. It was assumed on the basis of the results of the karyological analysis that among the Palearctic species S. baueri is most similar to the Baikalian endemics and S. electa is phylogenetically closer to S. prima. Specific features of the chromosome and morphological evolutions of the Sergentia genus species are considered.     

Haramonas viridissp. nov. (Raphidophyceae, Heterokontophyta), a new sand-dwelling raphidophyte from cold temperate waters

A new, marine, sand‐dwelling raphidophyte from Sylt, Germany, Haramonas viridis Horiguchi et Hoppenrath sp. nov. is described. This represents a second species in the previously monotypic genus Haramonas, which was originally described from a sand sample from a mangrove river mouth in tropical Australia, based on the type species, H. dimorpha. This new species from a cold temperate region: (i) possesses a tubular invagi‐nation in the posterior part of the cell; (ii) produces copious amounts of mucilage in culture; (iii) possesses both motile and non‐motile stages in its life cycle; and (iv) has overlapping discoidal chloroplasts, all of which are diagnostic features of the genus Haramonas. Therefore, it is indisputable that this species belongs to this genus. However, the species from Sylt differs from the type species of the genus in: (i) having a larger cell size; (ii) possessing a larger number of chloroplasts; and (iii) being greenish in color. The ultrastructural study revealed that the structure of the tubular invagi‐nation was the same as that of the type species.