Pub Date : 2021-07-03DOI: 10.1080/0269249X.2021.1982016
P. Siver
Aulacoseira is a freshwater diatom genus found today in numerous lakes, ponds and rivers worldwide, and inhabiting a wide range of environmental conditions. The genus is one of the oldest diatom lineages known to colonize freshwater environments, dating to the late Cretaceous and radiating over much of the Cenozoic. The purpose of this paper is to describe a new species, Aulacoseira chockii, from an early Eocene locality situated near the Arctic Circle in northern Canada. The exquisitely preserved specimens have allowed for a detailed examination of frustule morphology of this early Cenozoic taxon. Three characteristics clearly separate A. chockii from all other known fossil and modern species in the genus. First, the spines of A. chockii are formed by coalescence of extensions from three to five mantle costae and multiple ribs that originate on the valve face. This type of spine design has never been reported and represents a potentially ancient trait in the Aulacoseiraceae lineage. Second, the valve has multiple sessile rimoportulae that are each connected to the end of a tube or canal that runs parallel to, and inside, the mantle wall. Rimoportulae with this structure are rare, and found primarily on extinct species of Aulacoseira. Third, the mantle striae are sinistrorse, and represent another rarely observed character within the genus. Because frustules of A. chockii possessed only separation spines, existed largely as single cells and not in long filaments, and were found in associated with remains of numerous heliozoans as well as testate euglyphids and sponges, it is believed this species grew in the littoral zone of a shallow waterbody.
{"title":"Aulacoseira chockii sp. nov., an early freshwater centric diatom from the Eocene bearing a unique morphology","authors":"P. Siver","doi":"10.1080/0269249X.2021.1982016","DOIUrl":"https://doi.org/10.1080/0269249X.2021.1982016","url":null,"abstract":"Aulacoseira is a freshwater diatom genus found today in numerous lakes, ponds and rivers worldwide, and inhabiting a wide range of environmental conditions. The genus is one of the oldest diatom lineages known to colonize freshwater environments, dating to the late Cretaceous and radiating over much of the Cenozoic. The purpose of this paper is to describe a new species, Aulacoseira chockii, from an early Eocene locality situated near the Arctic Circle in northern Canada. The exquisitely preserved specimens have allowed for a detailed examination of frustule morphology of this early Cenozoic taxon. Three characteristics clearly separate A. chockii from all other known fossil and modern species in the genus. First, the spines of A. chockii are formed by coalescence of extensions from three to five mantle costae and multiple ribs that originate on the valve face. This type of spine design has never been reported and represents a potentially ancient trait in the Aulacoseiraceae lineage. Second, the valve has multiple sessile rimoportulae that are each connected to the end of a tube or canal that runs parallel to, and inside, the mantle wall. Rimoportulae with this structure are rare, and found primarily on extinct species of Aulacoseira. Third, the mantle striae are sinistrorse, and represent another rarely observed character within the genus. Because frustules of A. chockii possessed only separation spines, existed largely as single cells and not in long filaments, and were found in associated with remains of numerous heliozoans as well as testate euglyphids and sponges, it is believed this species grew in the littoral zone of a shallow waterbody.","PeriodicalId":11199,"journal":{"name":"Diatom Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48578340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-03DOI: 10.1080/0269249X.2021.1957719
Atchaneey Boonprakob, N. Lundholm, L. Medlin, Ø. Moestrup
The marine planktonic diatom genera Rhizosolenia, Proboscia, Pseudosolenia and Neocalyptrella have been studied with emphasis on morphology and phylogeny. Material was collected October 2008—January 2011 at seven localities in the four provinces of the marine coastal waters of Thailand: Rayong, Chonburi, Chumphon and Phuket. Fifty strains were established in culture and used for morphological and phylogenetic analyses, complemented with morphological studies of field material. Morphological studies were done using light microscopy, scanning and transmission electron microscopy. Ten species and two varieties of Rhizosolenia were identified and described in detail: R. styliformis, R. acuminata, R. bergonii, R. clevei var. clevei, R. clevei var. communis, R. formosa, R. hyalina, R. imbricata, R. ostenfeldii, R. aff. pungens, R. setigera and R. loanicola sp. nov. Pseudosolenia calcaravis was also found, and detailed studies indicated that this taxon formed a species complex. Proboscia was represented by P. indica and P. siamensis sp. nov., but more species probably exist. Neocalyptrella was represented by N. robusta. The molecular studies supported Pseudosolenia, Proboscia and Neocalyptrella as separate genera. Culturing and molecular analyses were often difficult or unsuccessful. The data show that Rhizosolenia can be a monophyletic genus if R. pungens and R. setigera, which are distantly related to the remaining Rhizosolenia species, are described as a new genus. This will be done in a companion study of the type material of R. setigera.
本文对海洋浮游硅藻属rhizzosolenia、Proboscia、Pseudosolenia和Neocalyptrella进行了形态学和系统发育的研究。材料于2008年10月至2011年1月在泰国沿海海域四个省的七个地点收集:罗勇、春武里、春丰和普吉岛。在培养中建立了50株菌株，用于形态学和系统发育分析，并辅以田间材料的形态学研究。形态学研究采用光镜、扫描电镜和透射电镜。十个物种和两个品种Rhizosolenia被确认和详细描述:r . styliformis r . acuminata r . bergonii r . clevei var. clevei, r . clevei var.普通的,r·福尔摩沙r . hyalina r . imbricata r . ostenfeldii r . aff. pungens, r . setigera和r . loanicola sp. 11月Pseudosolenia calcaravis还发现,和详细的研究表明这种分类单元形成一个物种复杂。长鼻目以籼稻P. indica和暹罗P. siamensis sp. nov为代表，但可能存在更多种类。以新桉树为代表。分子研究支持Pseudosolenia、Proboscia和Neocalyptrella为独立属。培养和分子分析往往困难或不成功。结果表明，如果将与根茎属其余种有亲缘关系的pungens和setigera作为一个新属来描述，根茎属可能是一个单系属。这将在一项关于赤藓类型材料的配套研究中进行。
{"title":"The morphology and phylogeny of the diatom genera Rhizosolenia, Proboscia, Pseudosolenia and Neocalyptrella from Gulf of Thailand and the Andaman Sea, with description of Rhizosolenia loanicola sp. nov., Proboscia siamensis sp. nov. and Probosciales ord. nov.","authors":"Atchaneey Boonprakob, N. Lundholm, L. Medlin, Ø. Moestrup","doi":"10.1080/0269249X.2021.1957719","DOIUrl":"https://doi.org/10.1080/0269249X.2021.1957719","url":null,"abstract":"The marine planktonic diatom genera Rhizosolenia, Proboscia, Pseudosolenia and Neocalyptrella have been studied with emphasis on morphology and phylogeny. Material was collected October 2008—January 2011 at seven localities in the four provinces of the marine coastal waters of Thailand: Rayong, Chonburi, Chumphon and Phuket. Fifty strains were established in culture and used for morphological and phylogenetic analyses, complemented with morphological studies of field material. Morphological studies were done using light microscopy, scanning and transmission electron microscopy. Ten species and two varieties of Rhizosolenia were identified and described in detail: R. styliformis, R. acuminata, R. bergonii, R. clevei var. clevei, R. clevei var. communis, R. formosa, R. hyalina, R. imbricata, R. ostenfeldii, R. aff. pungens, R. setigera and R. loanicola sp. nov. Pseudosolenia calcaravis was also found, and detailed studies indicated that this taxon formed a species complex. Proboscia was represented by P. indica and P. siamensis sp. nov., but more species probably exist. Neocalyptrella was represented by N. robusta. The molecular studies supported Pseudosolenia, Proboscia and Neocalyptrella as separate genera. Culturing and molecular analyses were often difficult or unsuccessful. The data show that Rhizosolenia can be a monophyletic genus if R. pungens and R. setigera, which are distantly related to the remaining Rhizosolenia species, are described as a new genus. This will be done in a companion study of the type material of R. setigera.","PeriodicalId":11199,"journal":{"name":"Diatom Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43899647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-03DOI: 10.1080/0269249X.2021.1972045
F. Minaoui, Z. Hakkoum, M. Douma, K. Mouhri, M. Loudiki
Microscopic algae especially diatoms (Class Bacillariophyceae) are an important component of biological soil crusts (or biocrust) communities in arid and semi-arid environments. In Morocco, a largely arid and semi-arid African Mediterranean country, the soil diatom diversity and ecology remain unexplored, unlike aquatic diatoms. This study aims to understand the spatial distribution of soil diatoms and to investigate the effects of soil properties and land use on their diversity and taxonomic composition in the region of Marrakesh (Morocco). Five sampling sites with different land use and vegetation cover were selected along a natural altitudinal gradient in the Ourika watershed (from the humid mountain highlands of Oukaimeden at 2634 m (High Atlas) to the arid Haouz plain at 765 m). Biological soil crusts were taken and soil physicochemical characteristics (soil moisture and texture, pH, electrical conductivity, total organic carbon, ammoniacal nitrogen, available phosphorus) were measured at five locations and two seasons (February and May). The spatial distribution of soil diatom communities and associated influencing factors were investigated via statistical analysis using Canonical Correspondence Analysis (CCA). A total of 27 diatom taxa belonging to 16 genera were recorded. The results showed that the distribution of soil diatoms was mainly influenced by altitude, bioclimate, substratum type, land use and vegetation cover. These environmental factors induce spatial variability in the soil physicochemical properties. Diatom composition and species richness were correlated with soil moisture, pH, texture, conductivity, nutrient and organic matter content. Diatoms showed higher species richness in siliceous soils of high altitudinal humid grassland dominated by acidophilous and neutral taxa with a preference for low conductivity. In contrast diatom communities of forests and sedimentary lowland arid steppe were relatively species poor, dominated by typically alkaliphilous and halophilous soil species. This exploratory survey provides a first account of the diatom assemblages of biological soil crusts over an altitudinal range in Morocco, necessary for understanding their structure and ecological function, including improving soil condition and sustainable fertility management.
{"title":"Diversity and spatial distribution of soil diatoms along a natural altitudinal gradient in the High Atlas (Morocco)","authors":"F. Minaoui, Z. Hakkoum, M. Douma, K. Mouhri, M. Loudiki","doi":"10.1080/0269249X.2021.1972045","DOIUrl":"https://doi.org/10.1080/0269249X.2021.1972045","url":null,"abstract":"Microscopic algae especially diatoms (Class Bacillariophyceae) are an important component of biological soil crusts (or biocrust) communities in arid and semi-arid environments. In Morocco, a largely arid and semi-arid African Mediterranean country, the soil diatom diversity and ecology remain unexplored, unlike aquatic diatoms. This study aims to understand the spatial distribution of soil diatoms and to investigate the effects of soil properties and land use on their diversity and taxonomic composition in the region of Marrakesh (Morocco). Five sampling sites with different land use and vegetation cover were selected along a natural altitudinal gradient in the Ourika watershed (from the humid mountain highlands of Oukaimeden at 2634 m (High Atlas) to the arid Haouz plain at 765 m). Biological soil crusts were taken and soil physicochemical characteristics (soil moisture and texture, pH, electrical conductivity, total organic carbon, ammoniacal nitrogen, available phosphorus) were measured at five locations and two seasons (February and May). The spatial distribution of soil diatom communities and associated influencing factors were investigated via statistical analysis using Canonical Correspondence Analysis (CCA). A total of 27 diatom taxa belonging to 16 genera were recorded. The results showed that the distribution of soil diatoms was mainly influenced by altitude, bioclimate, substratum type, land use and vegetation cover. These environmental factors induce spatial variability in the soil physicochemical properties. Diatom composition and species richness were correlated with soil moisture, pH, texture, conductivity, nutrient and organic matter content. Diatoms showed higher species richness in siliceous soils of high altitudinal humid grassland dominated by acidophilous and neutral taxa with a preference for low conductivity. In contrast diatom communities of forests and sedimentary lowland arid steppe were relatively species poor, dominated by typically alkaliphilous and halophilous soil species. This exploratory survey provides a first account of the diatom assemblages of biological soil crusts over an altitudinal range in Morocco, necessary for understanding their structure and ecological function, including improving soil condition and sustainable fertility management.","PeriodicalId":11199,"journal":{"name":"Diatom Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43052674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-03DOI: 10.1080/0269249X.2021.1974572
A. Kryk, A. Witkowski, Lourenço Ribeiro, J. Kociolek, S. Mayama, R. Wróbel, Y. Risjani, Yunianta, J. Bemiasa, E. Bemanaja
Regions with high levels of biodiversity, which mostly correspond to tropical regions, can be treated as treasuries of endemism, even for single-celled life forms. Learning about these areas, and the species present in them, is key to understanding the processes that govern their emergence and sustainability. This paper is a contribution towards revealing the biodiversity of marine benthic diatom species of the world. The samples used in this paper were taken from East Java (Indonesia), Nosy Be (north-west Madagascar) and the Tagus River estuary (Portugal). We describe a new diatom genus, Catenulopsis, and propose the first species of the genus from Nosy Be, named Catenulopsis catenulafalsa. We also describe two new Catenula species, one from Java (Catenula javanica) and the other from Portugal (Catenula brotasiae). The paper also discusses the characteristics of Catenula adhaerens and variations in the species across geographic space. We characterize the morphological variation of C. adhaerens in samples from equatorial West Africa, South Africa, Portugal, Japan, Madagascar and Indonesia.
{"title":"Novel Diatoms (Bacillariophyta) from tropical and temperate marine littoral habitats with the description of Catenulopsis gen. nov., and two Catenula species","authors":"A. Kryk, A. Witkowski, Lourenço Ribeiro, J. Kociolek, S. Mayama, R. Wróbel, Y. Risjani, Yunianta, J. Bemiasa, E. Bemanaja","doi":"10.1080/0269249X.2021.1974572","DOIUrl":"https://doi.org/10.1080/0269249X.2021.1974572","url":null,"abstract":"Regions with high levels of biodiversity, which mostly correspond to tropical regions, can be treated as treasuries of endemism, even for single-celled life forms. Learning about these areas, and the species present in them, is key to understanding the processes that govern their emergence and sustainability. This paper is a contribution towards revealing the biodiversity of marine benthic diatom species of the world. The samples used in this paper were taken from East Java (Indonesia), Nosy Be (north-west Madagascar) and the Tagus River estuary (Portugal). We describe a new diatom genus, Catenulopsis, and propose the first species of the genus from Nosy Be, named Catenulopsis catenulafalsa. We also describe two new Catenula species, one from Java (Catenula javanica) and the other from Portugal (Catenula brotasiae). The paper also discusses the characteristics of Catenula adhaerens and variations in the species across geographic space. We characterize the morphological variation of C. adhaerens in samples from equatorial West Africa, South Africa, Portugal, Japan, Madagascar and Indonesia.","PeriodicalId":11199,"journal":{"name":"Diatom Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48849347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-03DOI: 10.1080/0269249X.2021.1983467
L. Tudesque, René Le Cohu, B. Van de Vijver
We provide an update to our knowledge of the centric diatoms in the Tonle Sap Lake (Cambodia) by providing a new and highly detailed iconography of all observed taxa based on light and scanning electron microscopy. We highlight a distinctive flora, including a new genus Praecyclostephanos gen. nov. and five taxa new to science: Aulacoseira micropunctata sp. nov., A. spiralorimoportula sp. nov., Praecyclostephanos boengchhmariensis sp. nov., Stephanodiscus tonlesapensis sp. nov. and Urosolenia anlongreangensis sp. nov. The flora is mainly dominated by several species of the genus Aulacoseira. Within the Aulacoseira populations forming the background of the diatom community, taxa that reveal the change in environmental conditions appear sporadically, often as blooms. The wide range of life-forms related to their ability to float is another remarkable aspect of the centric diatom flora. This variability appears at several taxonomic scales. At the genus level, colonial and solitary life-forms are very well represented in their diversity. At the sub-genus level, mainly among the Aulacoseira species, communities present a wide range of buoyancy metrics. Accordingly, in addition to the taxonomic review, we provide additional information related to their potential as bioindicators to monitor the hydrodynamic aspects of the lake in both space and time.
{"title":"The diatom flora of the Tonle Sap Lake in Cambodia: Centrobacillariophycidae – inventory and description of five new taxa including Praecyclostephanos gen. nov.","authors":"L. Tudesque, René Le Cohu, B. Van de Vijver","doi":"10.1080/0269249X.2021.1983467","DOIUrl":"https://doi.org/10.1080/0269249X.2021.1983467","url":null,"abstract":"We provide an update to our knowledge of the centric diatoms in the Tonle Sap Lake (Cambodia) by providing a new and highly detailed iconography of all observed taxa based on light and scanning electron microscopy. We highlight a distinctive flora, including a new genus Praecyclostephanos gen. nov. and five taxa new to science: Aulacoseira micropunctata sp. nov., A. spiralorimoportula sp. nov., Praecyclostephanos boengchhmariensis sp. nov., Stephanodiscus tonlesapensis sp. nov. and Urosolenia anlongreangensis sp. nov. The flora is mainly dominated by several species of the genus Aulacoseira. Within the Aulacoseira populations forming the background of the diatom community, taxa that reveal the change in environmental conditions appear sporadically, often as blooms. The wide range of life-forms related to their ability to float is another remarkable aspect of the centric diatom flora. This variability appears at several taxonomic scales. At the genus level, colonial and solitary life-forms are very well represented in their diversity. At the sub-genus level, mainly among the Aulacoseira species, communities present a wide range of buoyancy metrics. Accordingly, in addition to the taxonomic review, we provide additional information related to their potential as bioindicators to monitor the hydrodynamic aspects of the lake in both space and time.","PeriodicalId":11199,"journal":{"name":"Diatom Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44082033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-03DOI: 10.1080/0269249X.2021.1982778
M. Cantonati, N. Angeli, Elena Arnaud, Matteo Galbiati, Éva Soróczki-Pintér, H. LANGE-BERTALOT
A faintly heteropolar Brachysira species, with an acutely rounded headpole and a base pole which is sometimes slightly protracted, found in two lakes in northern Italy and Corsica, is described and named Brachysira chiaruccii sp. nov. This proposed new species can be differentiated from similar species by recognizable characters or character combinations: valve outline and symmetry, shape of the apices and of the central area, striation density, size, anchor-shaped terminal raphe endings (SEM feature), ecology. Brachysira chiaruccii sp. nov. is so far known to colonize oligotrophic, circumneutral, sufficiently buffered, moderately low conductivity mountain lakes, whilst the typical habitat of the most similar (North American) heteropolar Brachysira species (B. ocalanensis) is dystrophic, very low alkalinity and pH environments. The description is based on SEM and LM micrographs which document the full spectrum of shape variability along the size diminution series (including girdle views), plastid arrangement and morphology, and ecological preferences, in particular along the pH-alkalinity gradient.
{"title":"A new Brachysira species from mountain lakes in northern Italy and Corsica","authors":"M. Cantonati, N. Angeli, Elena Arnaud, Matteo Galbiati, Éva Soróczki-Pintér, H. LANGE-BERTALOT","doi":"10.1080/0269249X.2021.1982778","DOIUrl":"https://doi.org/10.1080/0269249X.2021.1982778","url":null,"abstract":"A faintly heteropolar Brachysira species, with an acutely rounded headpole and a base pole which is sometimes slightly protracted, found in two lakes in northern Italy and Corsica, is described and named Brachysira chiaruccii sp. nov. This proposed new species can be differentiated from similar species by recognizable characters or character combinations: valve outline and symmetry, shape of the apices and of the central area, striation density, size, anchor-shaped terminal raphe endings (SEM feature), ecology. Brachysira chiaruccii sp. nov. is so far known to colonize oligotrophic, circumneutral, sufficiently buffered, moderately low conductivity mountain lakes, whilst the typical habitat of the most similar (North American) heteropolar Brachysira species (B. ocalanensis) is dystrophic, very low alkalinity and pH environments. The description is based on SEM and LM micrographs which document the full spectrum of shape variability along the size diminution series (including girdle views), plastid arrangement and morphology, and ecological preferences, in particular along the pH-alkalinity gradient.","PeriodicalId":11199,"journal":{"name":"Diatom Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41598907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-03DOI: 10.1080/0269249X.2021.1914737
Julian Uribe-Palomino, R. Gastineau, A. Richardson, N. Wade, Lucy Whittock, G. Hallegraeff
The large hemi-discoid diatom Palmerina ostenfeldii was common in subtropical Moreton Bay, Australia, following a flood in January 2011. All diatom cells exhibited diagnostic subapical folds settled by loricate peritrich ciliates, but which readily abandoned stressed diatom cells. We characterized both diatoms and ciliates by morphological and molecular analyses, including careful video observations on non-preserved cells immediately after collection. The fold in the diatom cell wall comprises a narrow shelf upon which the ciliates attach (on average seven per fold, and similar for the two folds of a single diatom cell) but without penetrating the diatom wall itself. Folds were fully developed in newly formed internal valves, indicating that the ciliates play no role in their morphogenesis. SSU rRNA sequences of P. ostenfeldii from Moreton Bay (with ciliates) differed by 25 bp (1.5%) from those of P. hardmaniana from Texas (without ciliates), but surprisingly rbcL chloroplast sequences for both diatom species were indistinguishable. The ciliate species epiphytic on P. ostenfeldii, previously referred to as the cold-water tintinnid Amphorella borealis could not be assigned to any known species. We formally describe it here as Vaginicola collariforma sp. nov. within the crown clade of peritrichs which also includes the closely related genus Cothurnia (but distinguished as having an external stalk). Beating of the peritrich oral cilia was observed to drive rotational movement of the large discoid diatoms as in a ferris wheel. The observed diatom-ciliate symbiosis may represent a unique evolutionary adaptation in which the ciliate is host-specific and attaches in a specific locality on the host cell.
{"title":"New observations on the large hemidiscoid diatom Palmerina ostenfeldii and its symbiotic ciliate Vaginicola collariforma sp. nov. from subtropical Australian waters","authors":"Julian Uribe-Palomino, R. Gastineau, A. Richardson, N. Wade, Lucy Whittock, G. Hallegraeff","doi":"10.1080/0269249X.2021.1914737","DOIUrl":"https://doi.org/10.1080/0269249X.2021.1914737","url":null,"abstract":"The large hemi-discoid diatom Palmerina ostenfeldii was common in subtropical Moreton Bay, Australia, following a flood in January 2011. All diatom cells exhibited diagnostic subapical folds settled by loricate peritrich ciliates, but which readily abandoned stressed diatom cells. We characterized both diatoms and ciliates by morphological and molecular analyses, including careful video observations on non-preserved cells immediately after collection. The fold in the diatom cell wall comprises a narrow shelf upon which the ciliates attach (on average seven per fold, and similar for the two folds of a single diatom cell) but without penetrating the diatom wall itself. Folds were fully developed in newly formed internal valves, indicating that the ciliates play no role in their morphogenesis. SSU rRNA sequences of P. ostenfeldii from Moreton Bay (with ciliates) differed by 25 bp (1.5%) from those of P. hardmaniana from Texas (without ciliates), but surprisingly rbcL chloroplast sequences for both diatom species were indistinguishable. The ciliate species epiphytic on P. ostenfeldii, previously referred to as the cold-water tintinnid Amphorella borealis could not be assigned to any known species. We formally describe it here as Vaginicola collariforma sp. nov. within the crown clade of peritrichs which also includes the closely related genus Cothurnia (but distinguished as having an external stalk). Beating of the peritrich oral cilia was observed to drive rotational movement of the large discoid diatoms as in a ferris wheel. The observed diatom-ciliate symbiosis may represent a unique evolutionary adaptation in which the ciliate is host-specific and attaches in a specific locality on the host cell.","PeriodicalId":11199,"journal":{"name":"Diatom Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/0269249X.2021.1914737","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48080425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-03DOI: 10.1080/0269249X.2021.1926332
K. Downey, M. Julius, E. Theriot, Andrew J. Alverson
A strong consensus has emerged that taxonomic classifications should be based on an underlying phylogenetic hypothesis. According to this view, named groups should be monophyletic, ensuring that a name uniquely matches the evolutionary history and biological attributes of a group of taxa. As originally conceived, the diatom genus Cyclotella is a large and morphologically diverse assemblage of taxa that we now know consists of several distantly related lineages. Considerable progress has been made in placing these lineages into different monophyletic genera. The genus Spicaticribra was originally described as monotypic and has features that suggest a close relationship to Cyclotella, but it has also retained some ancestral features that appear to differentiate it from Cyclotella. We sequenced two nuclear and two plastid genes to resolve the phylogenetic position of Spicaticribra and show that it is embedded within a clade that includes the type species of Cyclotella and, further, that maintaining Spicaticribra renders Cyclotella non-monophyletic. We transfer Spicaticribra species into Cyclotella, resolve related nomenclatural issues, and caution against using ancestral characters and character states for taxonomic classification.
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Pub Date : 2021-04-03DOI: 10.1080/0269249X.2021.1942221
B. Van de Vijver, J. Hürlimann, David M. Williams, Z. Levkov, C. E. Wetzel, L. Ector
During a biomonitoring assignment in the Swiss canton Ticino, an unknown Fragilaria taxon was discovered that could not be identified using the currently available literature. The results of a morphological comparison with the type material of F. recapitellata, based on light and scanning electron microscopy, showed that the new Swiss taxon has sufficient differences to be separated as a new species: Fragilaria subrecapitellata sp. nov. The new species can be separated by its lanceolate to elliptic-lanceolate valve outline with convex valve margins, and its smaller valves compared to F. recapitellata. The distribution and iconography of F. recapitellata in literature data is analysed. As a result of this analysis, Fragilaria deformis is appointed as the correct name for the taxon generally known as F. candidagilae or F. capucina var. capitellata (Grunow) Lange-Bertalot in Krammer & Lange-Bertalot.
在瑞士提契诺州的一次生物监测任务中，发现了一个未知的Fragilaria分类单元，该分类单元无法使用现有文献进行鉴定。根据光镜和扫描电子显微镜，将新的瑞士分类单元与金龟子属的模式物质进行形态学比较，结果表明，该分类单元具有足够的差异，可以作为一个新种进行分离：Fragilaria subredcapellata sp.nov，和它的较小的阀门相比，F.retaiterellata。分析了文献资料中金龟子的分布和图像学特征。根据这一分析，Fragilaria deformis被指定为分类单元的正确名称，该分类单元通常被称为F.candigilae或F.capucina var.capitellata（Grunow）Lange Bertalot in Krammer&Lange Bertolot。
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Pub Date : 2021-04-03DOI: 10.1080/0269249X.2021.1873194
David M. Williams
The relationship among diatom names, taxa and the various databases available is explored from a nomenclatural point of view. An example using the names in Entomoneis and Amphiprora are discussed in this context. The key point is that there need not be a connection between the name of a validly described species and its actual existence as a biological entity. Interpreting the names found in current databases as if they were all names of real biological entities may yield incorrect conclusions when documenting various aspects of diatom diversity.
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