管壳缝类硅藻中国新记录属种——非洲南氏藻

利用光学和电子显微镜对采自黄海水域的1个管壳缝类硅藻——非洲南氏藻进行了形态学研究,并对其地理分布进行了讨论。结果表明:(1)该种壳体带面呈矩形,壳面窄椭圆形,具有钝圆的末端。(2)壳缝居中,由两条等长的分支组成。(3)管壳缝由复杂、接合的肋突支撑,但无龙骨。(4)每条线纹仅有1个孔纹,壳套上最多有1列孔纹。(5)目前本种仅发现于南非萨尔达尼亚湾和中国黄海。非洲南氏藻是该属在中国的第一个报道种类,因此,该属也是在中国第一次报道。     

Phylogeny and morphology of Nemalionopsis shawii (Thoreales,Rhodophyta), a new generic record from mainland China

The freshwater red alga Nemalionopsis shawii Skuja is first reported for mainland China from specimens collected in Guangdong and Yunnan Province. Morphological observations and molecular sequences of rbcL and cox1 genes were used to identify and analyze the phylogenetic position of the samples. Samples from China formed a monophyletic clade with other N. shawii samples from Japan, Indonesia, and Nepal with robust support values. The pairwise genetic distances for N. shawii between the samples from China and other samples were 0.2–1.5% and 1.0–2.4% for rbcL and cox1, respectively. Both male and female reproductive structures were observed in the specimens from Guangdong, but only monosporangia in the specimen from Yunnan. The samples from China increase the diversity of morphological measurements for N. shawii. The discovery of this genus in mainland China results in a new record of a freshwater red alga for this country.     

Interspecific plastidial recombination in the diatom genus Pseudo‐nitzschia

Plastids are usually uni‐parentally inherited and genetic recombination between these organelles is seldom observed. The genus Pseudo‐nitzschia, a globally relevant marine diatom, features bi‐parental plastid inheritance in the course of sexual reproduction. This observation inspired the recombination detection we pursued in this paper over a ~1,400‐nucleotide‐long region of the plastidial rbcL, a marker used in both molecular taxonomy and phylogenetic studies in diatoms. Among all the rbcL‐sequences available in web‐databases for Pseudo‐nitzschia, 42 haplotypes were identified and grouped in five clusters by Bayesian phylogeny. Signs of hybridization were evident in four of five clusters, at both intra‐ and interspecific levels, suggesting that, in diatoms, (i) plastidial recombination is not absent and (ii) hybridization can play a role in speciation of Pseudo‐nitzschia spp.     

Zameioscirpus, a new genus of Cyperaceae from South America

Systematic studies of scirpoid species in the Andes showed the necessity to exclude one species each from Scirpus and Carex. They are combined in a new genus Zameioscirpus and a third new species is described. The autonomous generic position of Zameioscirpus within the Scirpeae is supported by a phylogenetic analysis based on rbcL and trnL-F sequencing data and by conspicuous morphological similarities.     

Investigation of a freshwater acrochaetioid alga (Rhodophyta) with molecular and morphological methods

An enigmatic acrochaetioid alga was collected from Niangziguan spring in Shanxi Province, northern China. Morphological data indicated that this alga reproduces exclusively asexually by monosporangia and its morphological characteristics suggested that it might be referred to Audouinella heterospora. To ascertain its phylogenetic position, phylogenetic trees were reconstructed using partial sequences of the plastid‐encoded gene (rbcL) and the nuclear‐encoded gene (SSU rDNA) applying Bayesian inference (BI), maximum parsimony (MP) and maximum likelihood (ML). However, phylogenetic reconstructions showed that this acrochaetioid alga does not belong in a clade with the genus Audouinella, but forms a clade with Thorea hispida (Thoreales). Based on this analysis it is concluded that A. heterospora represents the ‘chantransia’ stage of T. hispida.     

Developments in the taxonomy of silica‐scaled chrysophytes – from morphological and ultrastructural to molecular approaches

Taxonomy in silica‐scaled chrysophytes has gone through three morphological phases. From primary studies of the cell morphology in the 18th century, the focus was in the 20th century replaced by studies of the silica structures of the cell envelope. Now, in the latest decades the importance of DNA sequencing has been recognized, not only to support the taxonomic framework but also to obtain new understanding of taxonomic relations among particular taxa. In the first part of this review, we provide a historical overview of the developments in the taxonomy of scale‐bearing chrysophytes. In the second part, we present a phylogenetic reconstruction of chrysophyte algae, updated by newly obtained SSU rDNA and rbcL sequences of several isolated Synura, Mallomonas and Chrysosphaerella species. We detected significant incongruence between the phylogenies obtained from the different datasets, with the SSU rDNA phylogram being the most congruent with the morphological data. Significant saturation of the first rbcL codon position could indicate the presence of positive selection in the rbcL dataset. Within the Synurales, the relationships revealed by the phylogenetic analyses highlight the artificial infragenetic classification of Mallomonas and Synura, and the occurrence of cryptic diversity within a number of traditionally defined species. Finally, three new combinations are proposed based on the phylogenetic analyses: Tessellaria lapponica, Synura asmundiae and S. bjoerkii.     

MOLECULAR PHYLOGENY OF THE GREEN ALGAL ORDER PRASIOLALES (TREBOUXIOPHYCEAE,CHLOROPHYTA)1

The systematics of the Prasiolales was investigated by phylogenetic inference based on analyses of the rbcL and 18S rRNA genes for representatives of all four genera currently attributed to this order (Prasiococcus, Prasiola, Prasiolopsis, Rosenvingiella), including all type species. The rbcL gene had higher sequence divergence than the 18S rRNA gene and was more useful for phylogenetic inference at the ranks of genus and species. In the rbcL gene phylogeny, three main clades were observed, corresponding to Prasiola, Prasiolopsis, and Rosenvingiella. Prasiococcus was nested among species of Prasiola occurring in subaerial and supralittoral habitats. Trichophilus welckeri Weber Bosse, a subaerial alga occurring in the fur of sloths in Amazonia, was closely related to Prasiolopsis ramosa Vischer. The species of Prasiola were grouped into three well‐supported clades comprising (i) marine species, (ii) freshwater and terrestrial species with linear blades, and (iii) terrestrial species with rounded or fan‐shaped blades. Sequence divergence was unexpectedly low in the marine group, which included species with different morphologies. For the 18S rRNA gene, the phylogenetic analyses produced several clades observed for the rbcL gene sequence analysis, but, due to very little sequence variation, it showed considerably lower resolution for inference at the species and genus levels. Due to the low support of some internal branches, the results of the analyses did not allow an unambiguous clarification of the origin and the early evolution of the Prasiolales.     

Relationships of Droseraceae: a cladistic analysis of rbcL sequence and morphological data

Molecular support for the monophyly of Droseraceae and its phylogenetic relationships to other dicot families was investigated using parsimony analysis of nucleotide sequences of the large subunit of ribulose-1,5-bisphosphate carboxylase (rbcL). Analysis of 100 species of plants including families of subclasses Rosidae, Hamamelidae, Dilleniidae, and Caryophyllidae (sensu Cronquist) placed monophyletic Droseraceae in the same clade as Caryophyllidae and Nepenthaceae (Dilleniidae). In a second analysis of 14 species of Droseraceae, 15 caryophyllids, one Nepenthaceae, and three Santalales, a single most-parsimonious tree was found in which Droseraceae are monophyletic, although the position of Drosophyllum as a member of Droseraceae is only weakly supported. The rbcL tree identified four major lineages within genus Drosera: 1) Dionaea; 2) the regia-clade that contains only Drosera regia; 3) the capensis-clade that contains the South African and temperate species outside of Australia; and 4) the peltata-clade that consists of principally Australian endemics. A separate analysis of 14 morphological and phytochemical characters is in general agreement with the rbcL tree except for the placement of Nepenthes, Drosophyllum, and Drosera burmanni. A combined analysis of both data sets places Drosophyllum in a clade with Triphyophyllum (Dioncophyllaceae).     

23 Phylogenetic position of Alaria Fistulosa (laminariales,phaeophyceae) based on nuclear its and plastid coding genes

Alaria is a common kelp genus generally found in the lower intertidal and shallow subtidal regions of rocky shores in the cold waters of the northern Hemisphere. About 16 species are currently recognized worldwide and, of these, A. fistulosa is distinguished by having hollow midrib and large blades with 10–30 m in length and 30–90 cm in width. It is the only canopy‐producing kelp in the northwest Pacific, where it is restricted to the waters of north Hokkaido, Kamchatka, Aleutian Islands, and Alaska. In order to know the phylogenetic position of A. fistulosa, sequences of nr DNA ITS and plastid rbcL including spacer and psaA regions were determined in A. fistulosa and compared with homologous positions of newly sequenced putative relatives and with published sequences of other kelp species. Combined data of ITS and Rubisco spacer show that A. fistulosa was more related to the clade of Lessoniopsis and Pterygophora than to the clade of other species of Alaria, which is supported by the rbcL and psaA sequence data. The topologies from nuclear and plastid DNA sequences lead to phylogenetic independence of A. fistulosa, which is clearly different from the genus Alaria.     

A polyphasic approach to the study of the genus Nitzschia (Bacillariophyta): three new planktonic species from the Adriatic Sea

The paraphyletic diatom genus Nitzschia comprises over 1000 morphologically distinct pennate taxa, known from the benthos and plankton of freshwater, brackish, and marine environments. The principal diagnostic characters for delimitation of Nitzschia species include valve shape, the position and structure of the raphe, presence/absence and shape of the proximal raphe endings and terminal raphe fissures, areola structure, and specific morphometric features such as cell size, and stria and fibula density. In this study, we isolated 12 diatom strains into culture from samples collected at the surface or greater depths of the southeastern Adriatic Sea. Morphological analyses included LM, SEM, and TEM observations, which, along with specific morphometric features, allowed us to distinguish three new Nitzschia species. These findings were congruent with the results of phylogenetic analyses performed on nuclear‐encoded SSU (18S) rDNA and chloroplast‐encoded rbcL and psbC genes. One of the new species (Nitzschia dalmatica sp. nov.) formed a lineage within a clade of Bacillariaceae containing members of the Nitzschia sect. Dubiae, which was sister to Psammodictyon. A second lineage was part of a novel clade that is significantly distinct from other Nitzschia species sequenced so far and includes Nitzschia adhaerens sp. nov. and N. cf. adhaerens. A further new species was found, Nitzschia inordinata sp. nov., which appeared as the sister group to the N. adhaerens clade and the conopeoid Nitzschia species in our phylogenetic trees. Our findings contribute to the overall diversity of genus Nitzschia, especially in identifying some deep branches within the Bacillariaceae, and highlight under‐scoring of this genus in marine plankton.     

57 Systematics of hydropuntia montagne (gracilariaceae,gracilariales, rhodophyta) based on comparative morphology and rbcL sequence analysis

The taxonomic validity of the genus Hydropuntia Montagne (1843) (including Polycavernosa) within the Gracilariaceae (Gracilariales, Rhodophyta) is controversial. Morphological characters that define species of Hydropuntia are said to be variable and to overlap with those of Gracilaria. Here we present a global phylogenetic study of the family based on a Bayesian analysis of a large rbcL DNA sequence dataset indicating that the genus Hydropuntia forms a well supported monophyletic clade within the family, and recognize Hydropuntia as a genus distinct from Gracilaria. We also conducted smaller phylogenetic analyses in which thirty four Hydropuntia rbcL sequences resulted in two major clades within the genus, comprising a Caribbean clade and an Indo‐Pacific clade. Diagnostic reproductive stages that separate these two clades will be illustrated.     

A combined morphological and molecular approach to Nitzschia varelae sp. nov., with discussion of symmetry in Bacillariaceae

A previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschia as an independent genus. It is concluded that, while a core of hantzschioid species may exist that can be classified together, corresponding to the traditional understanding of the genus Hantzschia, there is no single morphological feature common to all of them that can be used to diagnose the group and differentiate it from the various hantzschioid lineages that are separate from true Hantzschia and currently placed in e.g. Nitzschia or Cymbellonitzschia. Testing whether a hantzschioid species does or does not belong to Hantzschia will in many cases require molecular evidence. Although the new coastal species does not belong to the same lineage as the type species of Nitzschia, N. sigmoidea, it is described for the moment as N. varelae Carballeira, D.G. Mann & Trobajo, sp. nov., until there is a better understanding of generic limits in the Bacillariaceae following a wider molecular and morphological survey of that family.     

Phylogeny of extant genera in the family Characeae (Charales,Charophyceae) based on rbcL,sequences and morphology

Extant genera of Characeae have been assigned to two tribes: Chareae (Chara, Lamprothamnium, Nitellopsis, and Lychnothamnus) and Nitelleae (Nitella and Tolypella), based on morphology of the thallus and reproductive structures. Character analysis of fossil and extant oogonia suggest that Tolypella is polyphyletic, the genus comprising two sections, one in each of the two tribes. Eleven morphological characters and sequence data for the Rubisco large subunit (rbcL) were used to reconstruct the phylogeny of genera, including the two sections of Tolypella. Parsimony analysis of the rbcL data, with all positions and changes weighted equally, strongly supports the monophyly of the Characeae. The two Tolypella sections form a robust monophyletic group basal to the family. Transversion weighting yielded the same tree but with a paraphyletic Tolypella. The rbcL data strongly support monophyly of tribe Chareae but tribe Nitelleae is paraphyletic. Parsimony analysis of morphological data produced one unrooted tree consistent with monophyly of the two tribes; on this tree the Tolypella sections were paraphyletic. Combining morphological with rbcL data did not change the results derived from rbcL sequences alone. The rbcL data support the monophyly of the Characeae and Coleochaete, which together form a monophyletic sister group to embryophytes.     

Phylogenomic analysis of pseudocryptic diversity reveals the new genus Deltalsia (Rhodomelaceae,Rhodophyta)

Molecular analyses, in combination with morphological studies, provide invaluable tools for delineating red algal taxa. However, molecular datasets are incomplete and taxonomic revisions are often required once additional species or populations are sequenced. The small red alga Conferva parasitica was described from the British Isles in 1762 and then reported from other parts of Europe. Conferva parasitica was traditionally included in the genus Pterosiphonia (type species P. cloiophylla in Schmitz and Falkenberg 1897), based on its morphological characters, and later transferred to Symphyocladia and finally to Symphyocladiella using molecular data from an Iberian specimen. However, although morphological differences have been observed between specimens of Symphyocladiella parasitica from northern and southern Europe they have yet to be investigated in a phylogenetic context. In this study, we collected specimens from both regions, studied their morphology and analyzed rbcL and cox1 DNA sequences. We determined the phylogenetic position of a British specimen using a phylogenomic approach based on mitochondrial and plastid genomes. Northern and southern European populations attributed to S. parasitica represent different species. Symphyocladiella arecina sp. nov. is proposed for specimens from southern Europe, but British specimens were resolved as a distant sister lineage to the morphologically distinctive Amplisiphonia, so we propose the new genus Deltalsia for this species. Our study highlights the relevance of using materials collected close to the type localities for taxonomic reassessments, and showcases the utility of genome-based phylogenies for resolving classification issues in the red algae.     

MOLECULAR PHYLOGENY OF THE GENUS KUMANOA (BATRACHOSPERMALES,RHODOPHYTA)1

Species belonging to the newly established genus Kumanoa were sampled from locations worldwide. DNA sequence data from the rbcL gene, cox1 barcode region, and universal plastid amplicon (UPA) were collected. The new sequence data for the rbcL were combined with the extensive batrachospermalean rbcL data available in GenBank. Single gene rbcL results showed the genus Kumanoa to be a well‐supported clade, and there was high statistical support for many of the terminal nodes. However, with this gene alone, there was very little support for any of the internal nodes. Analysis of the concatenated data set (rbcL, cox1, and UPA) provided higher statistical support across the tree. The taxa K. vittata and K. amazonensis formed a basal grade, and both were on relatively long branches. Three new species are proposed, K. holtonii, K. gudjewga, and K. novaecaledonensis; K. procarpa var. americana is raised to species level. In addition, the synonymy of K. capensis and K. breviarticulata is proposed, with K. capensis having precedence. Five new combinations are made, bringing the total number of accepted species in Kumanoa to 31. The phylogenetic analyses did not reveal any interpretable biogeographic patterns within the genus (e.g., K. spermatiophora from the tropical oceanic island Maui, Hawaii, was sister to K. faroensis from temperate midcontinental Ohio in North America). Previously hypothesized relationships among groups of species were not substantiated in the phylogenetic analyses, and no intrageneric classification is recommended based on current knowledge.