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The diversity of centric diatoms is documented for the transitional zone of the lower part of the Southern Bug River (Ukraine) just before entering the Dnipro-Bug Estuary and compared to earlier results from the upstream sampling sites of the same river system. Benthic samples of the following sites were investigated: north of Mykolaiv City (approximately 5 km), in Mykolaiv City (near Varvarivskyi Bridge), and 5 km south of the city. Twenty-four centric diatom taxa belonging to 11 genera were identified, analysed, and documented by scanning electron microscopy (SEM) and light microscopy (LM). Among them, Aulacoseira nivalis is the first report for Ukraine, A. islandica and is the first confirmed record for the studied area since the 1930s. The maximum number of centric diatom taxa found in one station was 21, the minimum 10. Melosira subglobosa was the most common (documented in 57–80% of sites with centric diatoms) and abundant species 7.3–15.7% in relative abundance to all diatom taxa. The discovered diversity of taxa and its comparison with previous results is discussed with regard to the relevance of estuary zones in the research of diatoms.

The International Code of Nomenclature (ICN) for algae, fungi, and plants calls for indexing of names in nomenclatural repositories (Turland 2018, Art. 42). Scientific names, new combinations, validations, and typifications of algae are novelties tracked by PhycoBank, the registration system for algae. PhycoBank was established and institutionalized at the Botanic Garden Berlin as the repository for nomenclatural acts concerning algae. Since June 2018, PhycoBank staff have been operating the registration system permanently. All data entered into the system undergo a curatorial process to assure a high level of data quality. PhycoBank’s three main components comprise a user-friendly data entry web application available for all registered submitters (self-registration allowed) and curators, a public data access portal, and a search engine that integrates most of the larger online repositories for algae names. The latter is not only a prerequisite for reliable data curation during the registration process but also a valuable, publicly available online tool for algae names. A fourth component still under development is handling the tight integration of the registration system with the workflow of digital publishers. The resulting data are expected to be of high quality and to have been intensively checked against existing nomenclatural acts worldwide. A crucial requirement for the data entry application is thus an intensive support for data validation and curation. Besides the search index giving access to a huge number of existing external names, the data entry application offers a set of tools for quality assurance. It supports and requires the creation of mostly fully atomized data that strictly follow the rules of the ICN. Additionally, completeness for core data is mandatory. Both, atomization and completeness are a precondition to achieve the required uniqueness in the dataset. Completeness also implies that new combinations can only be registered after or together with their original name. The same applies to bi- or trinomials and the respective uni- and binomials they are built on. The publicly available data portal allows accessing published registrations by searching for scientific names, nomenclatural authors, higher ranks and for each part of a bibliographic reference (such as bibliographic author, journal, title, year) stored in PhycoBank. Being a name centric application PhycoBank is neutral with respect to taxonomic opinions. Therefore, only nomenclatural synonymies (basionym or replaced synonym relationships) are stored in the system and names are not attached to a unique classification. Instead, to facilitate search via higher ranks as required by users, classification information is stored as a directed graph of higher taxa with registered names linking to this graph. By this, searches can be performed on multiple classifications simultaneously and can return all possible matches. PhycoBank uses http-based persistent identifiers (e.g. http://phycobank.org/102170), which makes them resolvable and actionable. These identifiers link to nomenclatural acts only and not to the information in the act. That is, a PhycoBank identifier should not be used to refer to a scientific name even if this name was established in the nomenclatural act. PhycoBank makes use of the application stack offered by the EDIT Platform for Cybertaxonomy (Kohlbecker 2017). However, as registration workflows essentially differ from other taxonomic workflows, a completely new user interface for editing has been developed, which provides the users with an intuitive and fluent user experience despite the high complexity of the data. The Common Data Model (Müller 2017) is the core data model for the Platform and already covered the vast majority of data types and fields required by the registration in terms of completeness and degree of atomization. For PhycoBank, it only needed to be extended by a single data type representing the registration/nomenclatural act itself. As of July 2022, PhycoBank includes 4,332 registrations, of which 4,202 are name novelties (1,523 in preparation or ready, 239 under curation, 2,407 published, and 33 rejected); 130 registrations refer to lectotypes or epitypes of existing names. PhycoBank will apply for recognition as a repository in 2022. This is a prerequisite for a proposal to make registration of nomenclatural acts for algae mandatory. This is possible before, at or after the 20th International Botanical Congress 2024.

A morphological study based on light microscopy and scanning electron microscopy describing three new Pseudostaurosira species from mountain streams in Central Mexico is presented herein. Epilithon and water samples for physico-chemical analyses were collected from eleven mountain streams in the Basin of Mexico, located within the Trans-Mexican Volcanic Belt. The bipolar Pseudostaurosira carmonae and P. caballeroae, and the tripolar P. iztaccihuatlii are described from Coaxcacoaco, San Rafael and Ameca streams, located at elevations above 2600 m. These streams were characterized by cold, well oxygenated, and neutral to slightly alkaline water with low conductivity and low nutrient concentration, descending from Mount Tlaloc and Iztaccihuatl volcano in the south eastern part of the basin. No teratological features were observed in either of these taxa, nor an intermediate state between the co-occurring bipolar and tripolar forms. The ultrastructure features (pore structure and spines position) were consistent with the defining characteristics of the genus Pseudostaurosira. This study contributes to further unravelling the freshwater diatom flora of Mexico, while denoting the importance of protecting and studying aquatic ecosystems in this overpopulated region of the Mexico.

In order to understand the taxonomy and phylogeny of the genus Gomphonema, the type of the name of the genus, G. acuminatum, and related species complexes are studied with an integrative taxonomic ...

Diatoms are among the most commonly used bioindicators. Correct taxonomic identifications are critical to their use as bioindicators because closely related diatom species can respond diffe...

DNA barcoding and metabarcoding is increasingly used to effectively and precisely assess and monitor biodiversity in aquatic ecosystems. As these methods rely on data availability and quality of barcode reference libraries, it is important to develop and follow best practices to ensure optimal quality and traceability of the metadata associated with the reference barcodes used for identification. Sufficient metadata, as well as vouchers, corresponding to each reference barcode must be available to ensure reliable barcode library curation and, thereby, provide trustworthy baselines for downstream molecular species identification. This document (1) specifies the data and metadata required to ensure the relevance, the accessibility and traceability of DNA barcodes and (2) specifies the recommendations for DNA harvesting and for the storage of both voucher specimens/samples and barcode data, (undefined)

Colonies of a new, stalked diatom species Gomphoneis tegelensis sp. nov. were sampled in September 2017 from Lake Tegel (Berlin, Germany) where this large species was first observed in 2009. Cultiv...

Epithemia hirudiniformis and three morphologically related taxa, described in Rhopalodia by O. Muller from material collected in East Africa at the end of the 19th and the beginning of the 20th century were re-evaluated and lectotypes designated. Rhopalodiella as a new subgenus is proposed which refines O. Muller's infrageneric classification and to which all these taxa belong. In addition, the type of Epithemia rhopala, described by Ehrenberg from Egypt, was studied to examine the assumed synonymy, introduced by Hustedt, with some of Muller's species. This study, using light and scanning electron microscopy, was not only based on historic material but also more recent material from Africa, including samples from the Island of Reunion from which the new species Epithemia vandevijveri is described. The distribution of Epithemia subg. Rhopalodiella, known to be restricted to tropical Africa, is discussed based on literature data and own observations. Corresponding to recent molecular-based studies, Rhopalodia is given a new status as subgenus.

A new marine diatom, Gomphonemopsis ligowskii, is described. Gomphonemopsis ligowskii was found as an epiphyte on the brown macrophyte, Desmarestia anceps, collected from King George Island, Antarc...

The International Code of Nomenclature (ICN) for algae, fungi, and plants provides for nomenclatural indexing through nomenclatural repositories (Turland et al. 2018, Art. 42). Registering nomenclatural novelties and nomenclatural acts means that repositories will keep track of names (species names and names at all ranks, replacement names, names proposed for conservation or rejection, validated names) and of nomenclatural types, including lectotypes and epitypes. Thus, PhycoBank has been advocated by different players such as the International Society for Diatom Research (ISDR), the Global Biodiversity Information Facility (GBIF), and the Special Committee on Registration of Algal and Plant Names (including fossils). Aided by a grant from the German Research Foundation (DFG, JA 874/8-1), PhycoBank has been established at the BGBM Berlin as the repository for nomenclatural acts of algae. As added value, PhycoBank deals with orthographical variants in linking the published spelling of a name to the corrected one with reference to the respective article of the ICN (Turland et al. 2018, Art. 60). Almost all nomenclatural acts are the result of taxonomic issues but also have implications for the taxonomic work of specialists worldwide. The challenge for implementing a registration system like PhycoBank is to inform individual scientists as well as to feed data into data networks, to strengthen their underlying names backbone linking scientific names to occurrences. Since June 2018, PhycoBank staff are operating the registration system using a user-friendly data entry web application. This interface for data entry by volunteers has been available since March 2019. All data entered into the system undergoes a curatorial process to assure a high level of data quality. The data entry web application is complemented by a public data access portal which is available under https://www.phycobank.org (Fig. 1). PhycoBank can be searched for scientific names (including unregistered formal or informal higher rank names), for categories of types and PhycoBank identifiers. PhycoBank assigns resolvable and globally unique HTTP-based identifiers for nomenclatural acts, e.g. for the genus Iconella, https://phycobank.org/100040. Via these PhycoBank identifiers, the corresponding data and metadata can be retrieved in human- and machine-readable formats. More than ten journals have published PhycoBank identifiers so far, allowing cross-linking between their PDF and the PhycoBank system. The Pensoft journals are pioneering an automatic registration workflow modeled and specified by the PhycoBank team. Classifications are frequently subject to changes. Currently, the algal classification is under discussion because of results from phylogenetic research. PhycoBank aims to be neutral with respect to higher classification, but tracks classification information of each name that is registered into a directed graph of available higher rank names to record fragments of higher classification information and to facilitate search functionalities. All scientists, editors, and publishers involved in the publication of nomenclatural novelties are invited to contact PhycoBank (curation@phycobank.org) to influence the prototypical registration process and to improve PhycoBank’s functionality.

Molecular data (rbcL and 18S) of 36 Planothidium strains were analysed. Twenty-seven strains were also studied morphologically by light microscopy and scanning electron microscopy: six strains from Berlin, two strains from the Faroe Islands, four strains from Lake Baikal, seven strains from Korea and eight strains from Mexico. The findings were compared to International Nucleotide Sequence Database Collaboration data of strains from New Zealand, Germany, France and the USA. The molecular and morphological data differentiated eight species, and the molecular trees underlined the clear differentiation between the two clades, with taxa possessing an asymmetrical central area on the sternum valve which is devoid of striae, either in the form of a sinus or of a cavum clustering together, versus the one taxon lacking a sinus or a cavum. In addition to Planothidium lanceolatum and P. cf. subantarcticum, the clade with a sinus contains two new species, P. cryptolanceolatum and P. taeansa, whereas the other clade ...

This paper is part of a project of studying benthic diatom biodiversity on marine coastal regions of Sweden with focus on rare and less known species. Two new species of Cocconeis Ehrenb. are described from Vrångö, a small island in the west coast of Sweden. Both species were found as epiphytic on the green alga Ulva intestinalis L. Cocconeis magnoareolata Al-Handal, Riaux-Gob., R.Jahn & A.K.Wulff sp. nov. is a small species not exceeding 9 µm in length and characterized by having large subquadrangular areolae on the sternum valve. Cocconeis vrangoensis Al-Handal & Riaux-Gob. sp. nov. appears similar to some taxa of the ‘Cocconeis scutellum complex’, but differs by its stria density on both valves and variable features of the areola and valvocopula ultrastructure. Detailed descriptions based on light and electron microscopy examination, a comparison with closely related taxa, as well as a description of the habitat of both species are here presented.

Background and aims – Within the project “German Barcode of Life – Diatoms” common diatoms of German waters were routinely isolated and cultivated. In order to understand the taxonomy and phylogeny of the genus Gomphonema, one of the most common taxa of Central Europe, known currently either under the name Gomphonema olivaceum in Europe or Gomphoneis olivacea in America, was studied. Methods – Twenty unialgal strains were established from five different water bodies in Germany and one from Lake Balaton, Hungary, which supplied molecular data (18S V4 and rbcL) besides morphometric and ultrastructural data. In addition, on eight populations from different water bodies including the type from Denmark, morphometric and micromorphological studies by light and scanning electron microscopy were performed. Key results – Molecular and micromorphological data show that the target taxon neither belongs to Gomphonema Ehrenb. nor to Gomphoneis Cleve. By reinstating the genus name Gomphonella Rabenh., the nomenclatural and taxonomic enigma of this taxon is solved, and with the presentation of the type by Hornemann the authorship of the epithet is clarified. Molecular data for the unialgal strains and several environmental clones show that there is more diversity in the Gomphonella olivacea clade than can be identified morphologically. In addition, the establishment of the new species Gomphonella coxiae and Gomphonella acsiae is supported. The molecular data classified Gomphonella species as belonging to the Cymbellales but not to the Gomphonemataceae. In addition, molecular data put Gomphoneis tegelensis R.Jahn & N.Abarca also into Gomphonella. In order to make the genera Gomphoneis and Gomphonema monophyletic, their astigmate members are transferred to Gomphonella. Conclusions – The results clarify that the gomphonemoid outline is not restricted to the family Gomphonemataceae but seem to be distributed across the entire order Cymbellales. This is shown in this paper for the revived genus Gomphonella, which contains the astigmate group of Gomphoneis and Gomphonema besides the longly disputed G. olivacea. Only a polyphasic approach, combining molecular and micromorphological data for taxonomy, nomenclatural evaluation, and observations from clonal cultures can reveal the full intricacies of evolutionary relations.

Knowledge on benthic diatom taxonomy and hence biodiversity from Arctic locations is rare, though the few existing analyses address morphological characteristics only. Morphological treatment is a time-consuming process and just allows the taxonomic identification of a low sample volume. In contrast, molecular sequencing is a faster and universally applicable approach, and also has the potential for refined analyses. Unfortunately, a lot of molecular information in databases is not trustable, and often existing genetic data do not fit together with morphological aspects. Therefore, the main goal of our study was for the first time to combine both morphological features and DNA information on benthic Arctic diatoms. In a first step, we studied the morphology of 26 strains from the Rostock Culture Collection of Arctic diatoms via light and electron microscopies. Secondly, we addressed their molecular taxonomy by sequencing the DNA barcode 18S V4 and the chloroplast marker rbcL. As a result, we could identify five species. Seven of the altogether twelve taxa could not be attributed to any known species, because listed sequences and morphology did not fit together. From these, three species were described as new to science here. Although the studied strains represent only a minor fraction of the diatom flora of Svalbard, this study is a first milestone in coupling morphological and molecular data of benthic diatoms in such high latitudes. By making these data available online, they contribute to a taxonomic reference library for Arctic benthic diatoms and are available for comparative studies.

The Melbourne Congress of 2011 authorized a Special Committee on Registration of Algal and Plant Names (including fossils), which was established the following year (Wilson in Taxon 61: 878–879. 2012). Its explicit mandate was “to consider what would be involved in registering algal and plant names (including fossils), using a procedure analogous to that for fungal names agreed upon in Melbourne and included in the Code as Art. 42”, but expectations at the Nomenclature Section in Melbourne went farther than that. There was the hope that registration systems for at least some of the main groups would soon be set up, to be used and tested on a voluntary basis and, if found to be generally accepted, would persuade the subsequent Congress in Shenzhen, in 2017, to declare registration of new names an additional requirement for valid publication. The Melbourne Congress also approved mandatory registration of nomenclatural novelties in fungi, starting on 1 Jan 2013. The new Art. 42 of the Code (McNeill & al. in Regnum Veg. 154. 2012) requires authors to register any fungal nomenclatural novelty, prior to publication, with a recognized repository, whereupon they are provided with a unique identifier for each name, to be included in the protologue along with other Code-mandated information. Years before registration became mandatory, mycologists had been encouraged, often prompted by journal editors, to register their nomenclatural novelties prior to publication. Most complied. Consequently, when mandatory registration was proposed, it had strong support from the mycological community. There are currently three recognized repositories for fungal names. They vary somewhat in how they operate, but they share records of their registered novelties as soon as publication has been effected. One consequence of implementing mandatory registration is that locating new fungal names and combinations and associated protologue information is much simpler now than it was before. This makes it easier to incorporate the information into taxonomic studies and to update taxonomic treatments, inventories, and indices. A corollary is that, no matter what publication outlet an author chooses, the name cannot fail to be noticed. The positive experience in mycology makes extension of the registration concept to plants and algae a compelling idea. That experience shows that the best way to make mandatory registration of nomenclatural novelties palatable to botanists and phycologists is the establishment of trial registration at repositories with a history of involvement in and commitment to the indexing of names. Trial registration enables users to acquaint themselves with registration procedures, make suggestions on how they might be improved, and appreciate, by personal experience, the benefits of registration. Unfortunately, the task of establishing such repositories proved to be more complex and time-consuming than had been foreseen. Substantial progress has been made in the establishment of such centres (Barkworth & al., in this issue, pp. 670–672) but the Committee is not in a position to make firm proposals to regulate registration procedures, even less to make registration mandatory from a concrete future date. Nevertheless, the Committee sees it as imperative that the Shenzhen Congress be offered the opportunity to move forward with registration without having to wait six more years. In this spirit, we offer the proposals below. Proposal (276) would declare registration an ongoing concern of the botanical, mycological, and phycological community and provide the basic structure for making it possible. Proposal (277) and Prop. (278) would, in addition, define a flexible framework within which a system of voluntary registration could be developed for various categories of organisms. Proposal (279) would provide for future mandatory registration in a way that does not depend on the six-year intervals between International Botanical Congresses. Presentation of each proposal is followed by a summary of the support received from members of the Committee. Fil: Barkworth, Mary E.. State University of Utah; Estados Unidos Fil: Watson, Mark. Royal Botanic Gardens; Reino Unido Fil: Barrie, Fred R.. Missouri Botanical Garden; Estados Unidos. Field Museum Of Natural History; Estados Unidos Fil: Belyaeva, Irina V.. Royal Botanic Gardens; Reino Unido Fil: Chung, Richard C. K.. Forest Research Institute ; Malasia Fil: Dasková, Jirina. Národní Muzeum; República Checa Fil: Davidse, Gerrit. Missouri Botanical Garden; Estados Unidos Fil: Dönmez, Ali A.. Hacettepe Üniversitesi; Turquía Fil: Doweld, Alexander B.. National Institute Of Carpology; Rusia Fil: Dressler, Stefan. Senckenberg Forschungsinstitut Und Naturmuseum; Alemania Fil: Flann, Christina. Naturalis Biodiversity Center; Países Bajos Fil: Gandhi, Kanchi. Harvard University; Estados Unidos Fil: Geltman, Dmitry. Russian Academy of Science; Rusia Fil: Glen, Hugh F.. Forest Hills; Sudáfrica Fil: Greuter, Werner. Freie Universität Berlin; Alemania Fil: Head, Martin J.. Brock University; Canadá Fil: Jahn, Regine. Freie Universität Berlin; Alemania Fil: Janarthanam, Malapati K.. Goa University; India Fil: Katinas, Liliana. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina Fil: Kirk, Paul M.. Royal Botanic Gardens; Reino Unido Fil: Klazenga, Niels. Royal Botanic Gardens Victoria; Australia Fil: Kusber, Wolf-Henning. Freie Universität Berlin; Alemania Fil: Kvacek, Jirí. Národní Muzeum; República Checa Fil: Malécot, Valéry. Universite D'angers; Francia Fil: Mann, David G.. Royal Botanic Gardens; Reino Unido Fil: Marhold, Karol. Charles University; República Checa Fil: Nagamasu, Hidetoshi. Kyoto University; Japón Fil: Nicolson, Nicky. Royal Botanic Gardens; Reino Unido Fil: Paton, Alan. Royal Botanic Gardens; Reino Unido Fil: Patterson, David J.. The University Of Sydney; Australia Fil: Price, Michelle J.. Conservatoire et Jardin botaniques de la Ville de Genève; Suiza Fil: van Reine, Willem F Prud' Homme. Naturalis Biodiversity Center; Países Bajos Fil: Schneider, Craig W.. Trinity College Hartford; Estados Unidos Fil: Sennikov, Alexander. Russian Academy Of Sciences; Rusia Fil: Smith, Gideon F.. Nelson Mandela Metropolitan University; Sudáfrica. Universidad de Coimbra; Portugal Fil: Stevens, Peter F.. Missouri Botanical Garden; Estados Unidos. University of Missouri; Estados Unidos Fil: Yang, Zhu-Liang. Kunming Institute Of Botany Chinese Academy Of Sciences; China Fil: Zhang, Xian-Chun. Chinese Academy of Sciences; República de China Fil: Zuccarello, Giuseppe C.. Victoria University Of Wellington; Nueva Zelanda

The Special Committee on Registration of Algal and Plant Names (including fossils) was established at the XVIII International Botanical Congress (IBC) in Melbourne in 2011, its mandate being to consider what would be involved in registering algal and plant names (including fossils), using a procedure analogous to that for fungal names agreed upon in Melbourne and included as Art. 42 in the International Code of Nomenclature for algae, fungi, and plants. Because experience with voluntary registration was key to persuading mycologists of the advantages of mandatory registration, we began by asking institutions with a history of nomenclatural indexing to develop mechanisms that would permit registration. The task proved more difficult than anticipated, but considerable progress has been made, as is described in this report. It also became evident that the Nomenclature Section needs a structure that will allow ongoing discussion of registration and associated issues. Simultaneously with this report we are submitting four proposals that would provide such a structure. Fil: Barkworth, Mary E.. State University of Utah; Estados Unidos Fil: Watson, Mark. Royal Botanic Gardens; Reino Unido Fil: Barrie, Fred R.. Field Museum of National History; Estados Unidos Fil: Belyaeva, Irina V.. Royal Botanic Gardens; Reino Unido Fil: Chung, Richard C. K.. Forest Research Institute Malaysia; Malasia Fil: Dašková, Jiřina. National Museum; República Checa Fil: Davidse, Gerrit. Missouri Botanical Garden; Estados Unidos Fil: Dönmez, Ali A.. Hacettepe Üniversitesi; Turquía Fil: Alexander B. Doweld. National Institute of Carpology; Rusia Fil: Dressler, Stefan. Senckenberg Forschungsinstitut und Naturmuseum; Alemania Fil: Flann, Christina. Naturalis Biodiversity Center; Países Bajos Fil: Gandhi, Kanchi. Harvard University; Estados Unidos Fil: Geltman, Dmitry. Institute of the Russian Academy of Sciences; Rusia Fil: Glen, Hugh F.. Forest Hills; Sudáfrica Fil: Greuter, Werner. Freie Universität Berlin; Alemania Fil: Head, Martin J.. Brock University; Canadá Fil: Jahn, Regine. Freie Universität Berlin; Alemania Fil: Janarthanam, Malapati K.. Goa University; India Fil: Katinas, Liliana. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Kirk, Paul M.. Royal Botanic Gardens; Reino Unido Fil: Klazenga, Niels. Royal Botanic Gardens; Australia Fil: Kusber, Wolf Henning. Freie Universität Berlin; Alemania Fil: Kvaček, Jiří. National Museum; República Checa Fil: Malécot, Valéry. Université d’Angers; Francia Fil: Mann, David G.. Royal Botanic Gardens; Reino Unido. Institute for Food and Agricultural Research and Technology; España Fil: Marhold, Karol. Charles University; República Checa Fil: Nagamasu, Hidetoshi. Kyoto University; Japón Fil: Nicolson, Nicky. Royal Botanic Gardens; Reino Unido Fil: Paton, Alan. Royal Botanic Gardens; Reino Unido Fil: Patterson, David J.. University of Sydney; Australia Fil: Price, Michelle J.. Conservatoire et Jardin botaniques de la Ville de Genève; Italia Fil: Prud'homme van Reine, Willem F.. Naturalis Biodiversity Center; Países Bajos Fil: Schneider, Craig W.. Trinity College; Estados Unidos Fil: Sennikov, Alexander. University of Helsinski; Finlandia Fil: Smith, Gideon F.. Nelson Mandela Metropolitan University; Sudáfrica Fil: Stevens, Peter F.. Missouri Botanical Garden; Estados Unidos. University of Missouri-St; Estados Unidos Fil: Yang, Zhu-Liang. Chinese Academy of Sciences; República de China Fil: Zhang, Xian-Chun. Chinese Academy of Sciences; República de China Fil: Zuccarello, Giuseppe C.. Victoria University of Wellington; Nueva Zelanda

Diatoms are used routinely to assess pollution level in rivers and lakes. Current methods are based on identification by light microscopy, which is laborious. An alternative is to identify species based on short DNA fragments and High-Throughput Sequencing (HTS). However a potential limitation is the incomplete coverage of species in reference barcode libraries. Usually these libraries are compiled by isolating cells, before culturing and sequencing them, which is tedious and often unsuccessful. Here we propose the use of rbcL sequences from environmental samples analysed by HTS. We set several criteria to ensure good sequence quality and correspondence with the target species observed in microscopy: the sequence needed to be abundant in the sample, and with no insertions nor deletions or stop codon, phylogenetic neighbour taxa had to correspond to neighbour taxonomic taxa expected from morphological observations. Four species from tropical rivers are given as examples, including one that is new to science. info:eu-repo/semantics/publishedVersion

To comply with the new phylogeny within the Surirellales as supported by molecular and morphological data, re-evaluations and re-combinations of taxa from and within the genera Surirella, Cymatopleura, and Stenopterobia and with the re-established genus Iconella are necessary. Since the African diatom flora is rich with taxa from these genera, especially Iconella, and the authors have studied these taxa recently, describing also new taxa, a preliminary checklist of African Iconella and Surirella is here presented. 94 names are contained on this list. 57 taxa have been transferred to Iconella; 55 taxa were formerly ranked within Surirella and two taxa within Stenopterobia. 10 taxa have stayed within Surirella and six taxa have been transferred from Cymatopleura to Surirella. 20 Surirella and 1 Stenopterobia names are listed which are either unrevised or unrevisable since morphological data is missing. Four names and taxa described by Ehrenberg are here typified. Two had been transferred to Iconella already: Iconella bifrons (Ehrenb.) Ruck & Nakov and Iconella splendida (Ehrenb.) Ruck & Nakov. Two are re-transferred from Cymatopleura to Surirella: Surirella librile (Ehrenb.) Ehrenb. and Surirella undulata (Ehrenb.) Ehrenb.; both taxa are currently known by their younger synonyms: Cymatopleura solea (Bréb.) W. Smith and Cymatopleura elliptica (Bréb. ex Kützing) W. Smith. Lectotypes for Iconella bifrons, I. splendida, Surirella librile, and S. undulata were designated.

Background - Otto Muller described seven varieties and forms of Cymatopleura solea from material from Central and East Africa. A re-investigation of the original material studied by Muller allowed us to lectotypify these taxa and describe another as new to science. Methods - Permanent diatom slides from original samples collected by Dr. Fulleborn in 1899 and 1900, and deposited at the Botanic Garden and Botanical Museum Berlin, Dahlem (B) were made. Additionally, material from Lake Victoria collected during the Third Tanganyika expedition conducted by Dr. Cunnington in 1904-1905, and kept at The National History Museum London (BM) were studied. Investigations were carried out using light microscopy and where possible also with scanning electron microscopy. Key results - Although Cymatopleura solea var. subconstricta and its forms major and minor are invalid, illustrations of Muller's concepts are shown and the taxon Cymatopleura comperei was described as new. On the other hand, the taxonomic entities var. clavata, var. laticeps and var. rugosa are redefined and raised to species rank: Cymatopleura clavata, C. laticeps and C. rugosa respectively. Additional morphological descriptions, based on light and scanning electron microscopy, are given for all these taxa where appropriate and their African distribution as based on literature and our own observations. In addition, the original slide of Cymatopleura nyansae, described from Central Africa by West, is also illustrated and discussed, firstly because it resembles the Cymatopleura laticeps valves which we observed in one of the historic samples from Lake Malawi examined by Muller, and secondly because often erroneous concepts of this taxon are present in the African literature.

Diatoms are frequently used for water quality assessments; however, identification to species level is difficult, time-consuming and needs in-depth knowledge of the organisms under investigation, as nonhomoplastic species-specific morphological characters are scarce. We here investigate how identification methods based on DNA (metabarcoding using NGS platforms) perform in comparison to morphological diatom identification and propose a workflow to optimize diatom fresh water quality assessments. Diatom diversity at seven different sites along the course of the river system Odra and Lusatian Neisse from the source to the mouth is analysed with DNA and morphological methods, which are compared. The NGS technology almost always leads to a higher number of identified taxa (270 via NGS vs. 103 by light microscopy LM), whose presence could subsequently be verified by LM. The sequence-based approach allows for a much more graduated insight into the taxonomic diversity of the environmental samples. Taxa retrieval varies considerably throughout the river system, depending on species occurrences and the taxonomic depth of the reference databases. Mostly rare taxa from oligotrophic parts of the river systems are less well represented in the reference database used. A workflow for DNA-based NGS diatom identification is presented. 28 000 diatom sequences were evaluated. Our findings provide evidence that metabarcoding of diatoms via NGS sequencing of the V4 region (18S) has a great potential for water quality assessments and could complement and maybe even improve the identification via light microscopy.

The planktonic freshwater diatom Cyclotella comensis Grunow is widely used as an indicator of oligotrophic lake conditions. Taxonomic confusion arose with the discrimination of the morphologically similar species Cyclotella pseudocomensis Scheffler and Cyclotella costei Druart & Straub. In this study, we used morphological and molecular data to investigate the relationship between C. comensis, C. pseudocomensis and C. costei using 11 strains from eight lakes in Germany and Austria. Morphological variability was high among the three morphospecies such that they could not be separated unambiguously using morphological traits. DNA sequence analysis revealed only minor differences in 18S V4 (

The first species described in the genus Encyonema were not lectotypified. Despite the absence of types, some specialists have either defended or accepted synonymizations based on their own concepts, such as in the cases of Encyonema prostratum, Gloionema paradoxum, G. leibleinii and E. paradoxum, the type of the genus Encyonema. We aimed to lectotypify E. paradoxum, E. prostratum, E. cespitosum, E. triangulum, Gloionema paradoxum, G. leibleinii and E. lacustre. Original material was inspected and characterized. These lectotypifications resulted in the verification of the conspecificity of E. paradoxum, E. prostratum and G. leibleinii, and in the designation of E. leibleinii comb. nov.

The nominate varieties of the monoraphid diatoms Cocconeis lineata Ehrenberg and C. euglypta Ehrenberg are typified. Lectotypes of both taxa are preserved at the Ehrenberg Collection, Museum fur Naturkunde, Berlin, Germany. The lectotype of C. lineata is a poorly detailed drawing, showing an ovoid valve (or frustule?) with two to three apical lines on each hemivalve. The lectotype of C. euglypta, contained in a mica, shows a unique, broadly elliptical sternum valve with up to five apical striae on each hemivalve, displaying a zigzag pattern. This is roughly consistent with the current concept of C. lineata and C. euglypta and with their usage over the last 160 years. To ensure stabilization of the names and current concepts for these two taxa, culture-based epitypes of C. lineata and C. euglypta are designated. Light and electron microscopy observations, as well as morphometric data from clones for both taxa, are presented and an amended description for each taxon is provided.