Search

Distimake vitifolius comb. nov. (Convolvulaceae), currently treated as Camonea vitifolia , is a common and widespread species in South-East Asia. A recent study on the re-delimitation of the genus Merremia classified its species into six genera. The results of molecular phylogenetic analyses and the presence of hexazonocolpate pollen informed the transfer of Merremia vitifolia to Camonea. We present new molecular, morphological and palynological data and reinterpret previous results, demonstrating that the species should be classified in Distimake instead, reflecting the phylogenetic relationships of the species. Thus, the occurrence of hexazonocolpate pollen in both Distimake and Camonea is found to be the result of the convergent evolution of this apertural pattern in 'Merremieae', with implications for pollen evolution studies in the family. We formally transfer Camonea vitifolia to Distimake and present this reclassification as an example of the relevance of reciprocal reinterpretation of different sources of evidence in systematic studies. [ABSTRACT FROM AUTHOR]

SUMMARY: Species diversity of Ulva in Vietnam was investigated using three commonly used genetic markers, the nuclear encoded rDNA ITS region and the plastid encoded rbcL and tufA genes. Single locus species delimitation methods, complemented with morphological and ecological information resulted in the delimitation of 19 species. This diversity is largely incongruent with the traditional understanding of Ulva diversity in Vietnam. Only four species identified in this study, U. lactuca, U. reticulata, U. spinulosa, and U. flexuosa, have been previously reported, and seven species, U. ohnoi, U. tepida, U. chaugulii, U. kraftiorum, U. meridionalis, U. limnetica, and U. aragoënsis, are recorded for the first time from Vietnam. Seven genetic clusters could not be associated with species names with certainty. A new species, U. vietnamensis, is described from marine to brackish coastal areas from southern Vietnam based on its morphological and molecular distinctiveness from the currently known Ulva species. A comparison with recent molecular‐based studies of Ulva diversity showed that species composition in Vietnam is similar to that of adjacent countries, including Japan, China, as well as Australia. Our study emphasizes the importance of molecular data in the assessment of Ulva diversity, and indicates that a lot of diversity may still remain to be discovered, especially in tropical regions. [ABSTRACT FROM AUTHOR]

These uncertainties in DNA-based species delimitation, along with conflicts between phylogenetic and traditional species definitions, and problems with linking DNA sequences to existing species names, have made phycologists hesitant about describing new species based solely on DNA sequence data. The primary aims of taxonomy are to name, circumscribe, describe and classify species. For example, within I S. shibazakiorum i , a genetically highly variable and widespread species for which species delimitation was found to be uncertain, additional nuclear gene data may result in the recognition of less inclusive entities, which will further our understanding of the biogeography and evolution of species within this group. The study by Hoshino et al. (2021), published in this issue, is an excellent example of how phycology has embraced DNA-based species delimitation methods, combined with other lines of biological evidence, including morphological, biogeographical, and breeding data, to arrive at taxonomic conclusions. [Extracted from the article]

Samples of Pithophoraceae, collected in diverse freshwater and damp terrestrial habitats from tropical and subtropical China, were characterized morphologically and ultrastructurally, and their phylogenetic position was determined based on nuclear ribosomal DNA sequences. Our phylogenetic analysis resolved a novel lineage of Pithophoraceae, sister to Aegagropilopsis. Based on our phylogenetic results, morphological observations and comparative rDNA ITS2 secondary structure analysis, we propose Chlorocladiella gen. nov., characterized by a well‐developed system of prostrate filaments, and describe four new species, C. cochlea sp. nov., C. erecta sp. nov., C. medogensis sp. nov., and C. pisformis sp. nov. Two species were found growing on damp soil, which is an unusual habitat for cladophoralean green algae, indicating that the diversity of Cladophorales in terrestrial habitats may be greater than currently recognized. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Pseudobryopsis was inferred as a distinct lineage in the Bryopsidineae which led us to establish the family Pseudobryopsidaceae. • Lambia antarctica was inferred as an early-branching lineage in Family Bryopsidaceae. • Resolved the relationship between Dichotomosiphonaceae, Caulerpaceae, and lineage containing the remaining core Halimedineae was resolved. • Core Halimedineae: several new lineages were inferred; Johnson-sea-linkia was reinstated. • A new classification scheme is proposed for the merger of families Pseudocodiaceae, Rhipiliaceae and Udoteaceae into a broadly circumscribed Halimedaceae and the establishment of tribes for the different lineages found therein. Abstract The Bryopsidales is a morphologically diverse group of mainly marine green macroalgae characterized by a siphonous structure. The order is composed of three suborders – Ostreobineae, Bryopsidineae, and Halimedineae. While previous studies improved the higher-level classification of the order, the taxonomic placement of some genera in Bryopsidineae (Pseudobryopsis and Lambia) as well as the relationships between the families of Halimedineae remains uncertain. In this study, we re-assess the phylogeny of the order with datasets derived from chloroplast genomes, drastically increasing the taxon sampling by sequencing 32 new chloroplast genomes. The phylogenies presented here provided good support for the major lineages (suborders and most families) in Bryopsidales. In Bryopsidineae, Pseudobryopsis hainanensis was inferred as a distinct lineage from the three established families allowing us to establish the family Pseudobryopsidaceae. The Antarctic species Lambia antarctica was shown to be an early-branching lineage in the family Bryopsidaceae. In Halimedineae, we revealed several inconsistent phylogenetic positions of macroscopic taxa, and several entirely new lineages of microscopic species. A new classification scheme is proposed, which includes the merger of the families Pseudocodiaceae, Rhipiliaceae and Udoteaceae into a more broadly circumscribed Halimedaceae, and the establishment of tribes for the different lineages found therein. In addition, the deep-water genus Johnson-sea-linkia , currently placed in Rhipiliopsis , was reinstated based on our phylogeny. [ABSTRACT FROM AUTHOR]

The presence of large densities of the piston-pumping polychaete Lanice conchilega can have important consequences for the functioning of marine sediments. It is considered both an allogenic and an autogenic ecosystem engineer, affecting spatial and temporal biogeochemical gradients (oxygen concentrations, oxygen penetration depth and nutrient concentrations) and physical properties (grain size) of marine sediments, which could affect functional properties of sediment-inhabiting microbial communities. Here we investigated whether density-dependent effects of L. conchilega affected horizontal (m-scale) and vertical (cm-scale) patterns in the distribution, diversity and composition of the typical nosZ gene in the active denitrifying organisms. This gene plays a major role in N2O reduction in coastal ecosystems as the last step completing the denitrification pathway. We showed that both vertical and horizontal composition and richness of nosZ gene were indeed significantly affected when large densities of the bio-irrigator were present. This could be directly related to allogenic ecosystem engineering effects on the environment, reflected in increased oxygen penetration depth and oxygen concentrations in the upper cm of the sediment in high densities of L. conchilega. A higher diversity (Shannon diversity and inverse Simpson) of nosZ observed in patches with high L. conchilega densities (3,185–3,440 ind. m-2) at deeper sediment layers could suggest a downward transport of NO3− to deeper layers resulting from bio-irrigation as well. Hence, our results show the effect of L. conchilega bio-irrigation activity on denitrifying organisms in L. conchilega reefs. [ABSTRACT FROM AUTHOR]

The taxonomy of the Cladophoraceae, a large family of filamentous green algae, has been problematic for a long time due to morphological simplicity, parallel evolution, phenotypic plasticity, and unknown distribution ranges. Partial large subunit ( LSU) rDNA sequences were generated for 362 isolates, and the analyses of a concatenated dataset consisting of unique LSU and small subunit ( SSU) rDNA sequences of 95 specimens greatly clarified the phylogeny of the Cladophoraceae. The phylogenetic reconstructions showed that the three currently accepted genera Chaetomorpha, Cladophora, and Rhizoclonium are polyphyletic. The backbone of the phylogeny is robust and the relationships of the main lineages were inferred with high support, only the phylogenetic position of both Chaetomorpha melagonium and Cladophora rupestris could not be inferred unambiguously. There have been at least three independent switches between branched and unbranched morphologies within the Cladophoraceae. Freshwater environments have been colonized twice independently, namely by the freshwater Cladophora species as well as by several lineages of the Rhizoclonium riparium clade. In an effort to establish monophyletic genera, the genera Acrocladus and Willeella are resurrected and two new genera are described: Pseudorhizoclonium and Lurbica. [ABSTRACT FROM AUTHOR]

Given the problems of species delimitation in algae using morphology or sexual compatibility, molecular data are becoming the standard for delimiting species and testing their traditional boundaries. The idea that species are separately evolving metapopulation lineages, along with theoretical progress in phylogenetic and population genetic analyses, has led to the development of new methods of species delimitation. We review these recent developments in DNA-based species delimitation methods, and discuss how they have changed and continue to change our understanding of algal species boundaries. Although single-locus approaches have proven effective for a first rapid and large-scale assessment of species diversity, species delimitation based on single gene trees falls short due to gene tree–species tree incongruence, caused by confounding processes like incomplete lineage sorting, trans-species polymorphism, hybridization and introgression. Data from unlinked loci and multi-species coalescent methods, which combine principles from phylogenetics and population genetics, may now be able to account for these complicating factors. Several of these methods also provide statistical support regarding species boundaries, which is important because speciation is a process and therefore uncertainty about precise species boundaries is inevitable in recently diverged lineages. [ABSTRACT FROM AUTHOR]

The widespread view of taxonomy as an essentially retrogressive and outmoded science unable to cope with the current biodiversity crisis stimulated us to analyze the current status of cataloguing global algal diversity. Contrary to this largely pessimistic belief, species description rates of algae through time and trends in the number of active taxonomists, as revealed by the web resource AlgaeBase, show a much more positive picture. More species than ever before are being described by a large community of algal taxonomists. The lack of any decline in the rate at which new species and genera are described, however, is indicative of the large proportion of undiscovered diversity and bears heavily on any prediction of global algal species diversity and the time needed to catalogue it. The saturation of accumulation curves of higher taxa (family, order, and classes) on the other hand suggest that at these taxonomic levels most diversity has been discovered. This reasonably positive picture does not imply that algal taxonomy does not face serious challenges in the near future. The observed levels of cryptic diversity in algae, combined with the shift in methods used to characterize them, have resulted in a rampant uncertainty about the status of many older species. As a consequence, there is a tendency in phycology to move gradually away from traditional names to a more informal system whereby clade-, specimen- or strain-based identifiers are used to communicate biological information. Whether these informal names for species-level clades represent a temporary situation stimulated by the lag between species discovery and formal description, or an incipient alternative or parallel taxonomy, will be largely determined by how well we manage to integrate historical collections into modern taxonomic research. Additionally, there is a pressing need for a consensus about the organizational framework to manage the information about algal species names. An eventual strategy should preferably come out of an international working group that includes the various databases as well as the various phycological societies. In this strategy, phycologists should link up to major international initiatives that are currently being developed, such as the compulsory registration of taxonomic and nomenclatural acts and the introduction of Life Science Identifiers. [ABSTRACT FROM AUTHOR]

We reassessed the taxonomy of dentate Dictyota species formerly attributed to D. ciliolata and D. crenulata. Both taxa have long been assumed to be broadly distributed in tropical to warm-temperate seas. Recent molecular data, however, provided evidence that D. crenulata constituted a complex of at least four species with restricted geographical distributions. Based on those results and careful morphological examination, we split D. crenulata sensu lato into D. crenulata sensu stricto restricted to Pacific Central America, D. jamaicensis with a tropical amphi-Atlantic distribution and D. canariensis and D. pleiacantha sp. nov. from Macaronesia. Morphological analysis showed that these species were distinguished by subtle morphological differences. In contrast to D. crenulata sensu lato, the wide tropical distribution of D. ciliolata was confirmed by DNA data. In addition, psbA sequence analysis did not provide evidence to segregate D. menstrualis and D. plectens from D. ciliolata. [ABSTRACT FROM AUTHOR]

The green algal family Chlorochytriaceae comprises relatively large coccoid algae with secondarily thickened cell walls. Despite its morphological distinctness, the family remained molecularly uncharacterized. In this study, we investigated the morphology and phylogenetic position of 16 strains determined as members of two Chlorochytriaceae genera, Chlorochytrium and Scotinosphaera. The phylogenetic reconstructions were based on the analyses of two data sets, including a broad, concatenated alignment of small subunit rDNA and rbcL sequences, and a 10-gene alignment of 32 selected taxa. All analyses revealed the distant relation of the two genera, segregated in two different classes: Chlorophyceae and Ulvophyceae. Chlorochytrium strains were inferred in two distinct clades of the Stephanosphaerinia clade within the Chlorophyceae. Whereas clade A morphologically fits the description of Chlorochytrium, the strains of clade B coincide with the circumscription of the genus Neospongiococcum. The Scotinosphaera strains formed a distinct and highly divergent clade within the Ulvophyceae, warranting the recognition of a new order, Scotinosphaerales. Morphologically, the order is characterized by large cells bearing local cell wall thickenings, pyrenoid matrix dissected by numerous anastomosing cytoplasmatic channels, sporogenesis comprising the accumulation of secondary carotenoids in the cell periphery and almost simultaneous cytokinesis. The close relationship of the Scotinosphaerales with other early diverging ulvophycean orders enforces the notion that nonmotile unicellular freshwater organisms have played an important role in the early diversification of the Ulvophyceae. [ABSTRACT FROM AUTHOR]

A new species ofTetraselmis,T. indicaArora & Anil, was isolated from nanoplankton collected from salt pans in Goa (India) and is described based on morphological, ultrastructural, 18S rRNA gene sequence and genome size data. The species is characterized by a distinct eyespot, rectangular nucleus, a large number of Golgi bodies, two types of flagellar pit hairs and a characteristic type of cell division. In nature, the species was found in a wide range of temperatures (48°C down to 28°C) and salinities, from hypersaline (up to 350 psu) down to marine (c. 35 psu) conditions. Phylogenetic analysis based on 18S rDNA sequence data showed thatT. indicais most closely related to unidentifiedTetraselmisstrains from a salt lake in North America. [ABSTRACT FROM PUBLISHER]

The microfilamentous green alga Uronema curvatum is widely distributed along the western and eastern coasts of the north Atlantic Ocean where it typically grows on crustose red algae and on haptera of kelps in subtidal habitats. The placement of this marine species in a genus of freshwater Chlorophyceae had been questioned. Molecular phylogenetic analysis of nuclear-encoded small and large subunit rDNA sequences reveal that U. curvatum is closely related to the ulvophycean order Cladophorales, with which it shares a number of morphological features, including a siphonocladous level of organization and zoidangial development. The divergent phylogenetic position of U. curvatum, sister to the rest of the Cladophorales, along with a combination of distinctive morphological features, such as the absence of pyrenoids, the diminutive size of the unbranched filaments and the discoid holdfast, warrants the recognition of a separate genus, Okellya, within a new family of Cladophorales, Okellyaceae. The epiphytic Urospora microscopica from Norway, which has been allied with U. curvatum, is revealed as a member of the cladophoralean genus Chaetomorpha and is herein transferred to that genus as C. norvegica nom. nov. [ABSTRACT FROM AUTHOR]

Abstract: The Siphonocladales are tropical to warm-temperate, marine green macro-algae characterized by a wide variety of thallus morphologies, ranging from branched filaments to pseudo-parenchymatous plants. Phylogenetic analyses of partial large subunit (LSU) rDNA sequences sampled from 166 isolates revealed nine well-supported siphonocladalean clades. Analyses of a concatenated dataset of small subunit (SSU) and partial LSU rDNA sequences greatly clarified the phylogeny of the Siphonocladales. However, the position of the root of the Siphonocladales could not be determined unambiguously, as outgroup rooting and molecular clock rooting resulted in a different root placement. Different phylogenetic methods (likelihood, parsimony and distance) yielded similar tree topologies with comparable internal node resolution. Likewise, analyses under more realistic models of sequence evolution, taking into account differences in evolution between stem and loop regions of rRNA, did not differ markedly from analyses using standard four-state models. The molecular phylogeny revealed that all siphonocladalean architectures may be derived from a single Cladophora-like ancestor. Parallel and convergent evolution of various morphological characters (including those traditionally employed to circumscribe the families and genera) have occurred in the Siphonocladales. Consequently, incongruence with traditional classifications, including non-monophyly in all families and most genera, was shown. [Copyright &y& Elsevier]

Abstract: Despite the potential model role of the green algal genus Codium for studies of marine speciation and evolution, there have been difficulties with species delimitation and a molecular phylogenetic framework was lacking. In the present study, 74 evolutionarily significant units (ESUs) are delimited using 227 rbcL exon 1 sequences obtained from specimens collected throughout the genus’ range. Several morpho-species were shown to be poorly defined, with some clearly in need of lumping and others containing pseudo-cryptic diversity. A phylogenetic hypothesis of 72 Codium ESUs is inferred from rbcL exon 1 and rps3–rpl16 sequence data using a conventional nucleotide substitution model (GTR+Γ+I), a codon position model and a covariotide (covarion) model, and the fit of a multitude of substitution models and alignment partitioning strategies to the sequence data is reported. Molecular clock tree rooting was carried out because outgroup rooting was probably affected by phylogenetic bias. Several aspects of the evolution of morphological features of Codium are discussed and the inferred phylogenetic hypothesis is used as a framework to study the biogeography of the genus, both at a global scale and within the Indian Ocean. [Copyright &y& Elsevier]

A reassessment of the genus Cladophoropsis results in the recognition of six morphospecies: C. macromeres, C. magna, C. membranacea, C. philippinensis, C. sundanensis and C. vaucheriiformis. The emended genus Cladophoropsis is characterized by mat- or cushion-forming plants attached to the substratum by tenacular cells or by rhizoids that sprout from the proximal pole of the basal cells or are formed in any part of the thallus, cell division by centripetal wall ingrowths or occasionally segregative, cells producing a single lateral but older cells occasionally producing secondary laterals, cross walls at the base of the laterals either absent or their formation markedly delayed and reinforcement of the thallus by entangling of the filaments or by anastomosis of adjacent filaments by tenacular cells. The different species are distinguished from each other based on thallus structure, mode of cell division, organization of branch systems, mode of thallus attachment and reinforcement, shape and dimensions of the cells and shape of the crystalline cell inclusions. Twenty Cladophoropsis species are excluded from the genus, including the widely distributed Indo-Pacific species C. herpestica and C. javanica, which have been found to be unrelated to other Cladophoropsis species but instead allied with species of the Cladophora section Longi-articulatae. Phylogenetic studies based on molecular data have furthermore demonstrated that Cladophoropsis is closely related to Boodlea, Phyllodictyon, Struveopsis, Struvea and Chamaedoris and that the genus probably does not form a natural group within this genus complex. Morphologically this can be illustrated by a number of Cladophoropsis species (e.g. C. magna and C. membranacea) crossing generic boundaries by sharing common features with Chamaedoris, Boodlea, Phyllodictyon and Struvea. For the benefit of taxonomic stability, Cladophoropsis is presently maintained, awaiting additional molecular evidence. [ABSTRACT FROM AUTHOR]

The marine benthic green and brown macroalgae of Rodrigues, collected during an expedition in October 2001, are documented and 18 of the 60 taxa of Chlorophyta (53 species) and 18 species of Phaeophyceae are illustrated. Fifty taxa of green and 12 taxa of brown algae are added to the existing species list of the island. Turf algae and smaller epiphytic species are not or are only sporadically included in this study. All records are listed with bibliographic, biogeographic, taxonomic and nomenclatural comments. Infrageneric identification keys are included. The new combination Caulerpa mexicana var. exposita is proposed and the discovery of a new Udotea species is mentioned. The algal flora of Rodrigues is of a typical Indian Ocean composition but appears to be relatively poor when compared to the nearby island of Mauritius. [ABSTRACT FROM AUTHOR]

• Diversity of genus Lobophora is reassessed in the western Indian Ocean. • A total of forty-three species are recognized. • Twenty-nine species appear endemic to the western Indian Ocean. • Fifteen species are described as new. The brown algal genus Lobophora (Dictyotales, Phaeophyceae) is an important ecological component of tropical marine systems. Although still scantily sampled, 35 species of Lobophora were discovered previously from the western Indian Ocean. This study updates previous diversity estimates by incorporating recent collections from Madagascar, Mozambique, and the Red Sea, considerably improving our knowledge of Lobophora diversity and biogeography in this region. Eight additional species are identified from the western Indian Ocean, raising the total number of Lobophora species to 43. Fifteen species are new to science and described herein. With ca. 40% of the global diversity, the western Indian Ocean is second only to the Central Indo-Pacific. Of the species identified to date, 29 appear to be restricted to the western Indian Ocean, three are shared with the Atlantic (four including L. lessepsiana introduced to the western Mediterranean Sea) and 12 have a wider distribution in the Indo-Pacific. The western Indian Ocean supports a high diversity with ca. 67% of its Lobophora restricted to this region, which is comparable to the Central Indo-Pacific (62%) and the Caribbean (61%). The presence of several putative endemic species in the western Indian Ocean islands and the Red Sea illustrates that these provinces played an important role in Lobophora species diversification within the western Indian Ocean by producing locally new species. The small number of species shared between the western Indo-Pacific and Atlantic indicates that this oceanic boundary – associated with the temperate Agulhas marine province, and the Benguela current and upwelling – acts as an effective dispersal barrier. [ABSTRACT FROM AUTHOR]