Eileen J Cox

Natural History Museum, London · Department of Life Sciences

Specimens of a new species of blue diatoms from the genus Haslea Simonsen were discovered in geographically distant sampling sites, first in the Canary Archipelago, then North Carolina, Gulf of Naples, the Croatian South Adriatic Sea, and Turkish coast of the Eastern Mediterranean Sea. An exhaustive characterization of these specimens, using a comb...

Dissolved silicon (DSi) is biologically processed to produce siliceous skeletons by a variety of organisms including radiolarians, silicoflagellates, choanoflagellates, plants, diatoms and some animals. In the photic ocean, diatoms are dominant consumers over competing other silicifiers. In Antarctica, where DSi is not particularly limiting, diatom...

Dissolved silicon (DSi) is biologically processed to produce siliceous skeletons by a variety of organisms including radiolarians, silicoflagellates, choanoflagellates, plants, diatoms and some animals. In the photic ocean, diatoms are dominant consumers over competing other silicifiers. In Antarctica, where DSi is not particularly limiting, diatom...

During a survey of freshwater diatoms from streams in North Tianmu Mountain, Liyang City, Jiangsu Province, China, a new Cymbella species, Cymbella liyangensis sp. nov. was recorded. A detailed morphological description of C. liyangensis is presented, based on light and scanning electron microscopy. The main features of C. liyangensis are: moderate...

Four new species are described in the genus Odontidium from the Himalaya in Nepal, and the Garhwal and Kumaon regions in India using light and electron microscopy. We compare the Himalayan taxa to recently described species from the European Alps and Macedonia. In addition we illustrate some specimens of Diatoma rupestris, a species recently descri...

The website ‘Diatom Flora of Britain and Ireland’ is an online identification tool for researchers with an interest in diatom taxonomy and ecology. It documents taxa found in Britain and Ireland using light and electron microscope images and incorporates recent taxonomic revisions. The website is hosted by Amgueddfa Cymru – National Museum Wales (h...

Rationale Potential post‐mortem alteration to the oxygen isotope composition of biogenic silica is critical to the validity of palaeoclimate reconstructions based on oxygen isotope ratios (δ¹⁸O values) from sedimentary silica. We calculate the degree of oxygen isotope alteration within freshly cultured diatom biogenic silica in response to heating...

The popularity of aquatic bioassessments has increased in Europe and worldwide, with a considerable number of methods being based on benthic diatoms. Recent evidence from molecular data and mating experiments has shown that some traditional diatom morphospecies represent species complexes, containing several to many cryptic species. This case study...

Recently published phylogenetic analyses of 52 strains of Navicula cryptocephala -like diatoms confirmed the existence of genetically distinct lineages within N . cryptocephala : clade I “RBG” and clade II “Lubnaig”. Using geometric morphometry, we compared strains of both clades with the lectotype and found that clade I represents N . cryptocephal...

During a survey of the diatom flora of some caves on Île de la Possession, the main island of the Crozet archipelago, a small, unusual naviculoid taxon was observed, initially identified as Fallacia lenzii. The new taxon is described as Fallacia emmae but it shows features of two related genera: Fallacia and Germainiella. Thorough morphological res...

The model diatom Thalassiosira pseudonana is believed to be a single species with a global distribution, but it has not been confirmed previously whether isolates from different environmental and geographic origins are genotypically and phenotypically identical. In the present study, a polyphasic approach was employed to characterize nine clonal is...

Background and aims - Gomphonema parvulum sensu lato contains a number of morphologically distinguishable varieties and forms that also show variation in their distribution and ecological ranges. As part of a study to investigate the ecophysiology of this taxon in relation to its use as a bio-indicator, clones from a range of sites in the UK were e...

Although it is often suggested that diatom wall morphology is faithfully replicated at each cell division, it is also well known that the average cell size of a diatom population usually decreases as cells proliferate. Comparisons between the two valves of a single frustule may also reveal morphological differences, indicating that valve ontogeneti...

Accurate taxonomic identification provides the foundation for a number of diatom applications, such as the ecological monitoring of waters and the reconstruction of past environments. Despite significant recent developments in diatom taxonomy and phylogenetics, to date, only a few taxa have been studied extensively using a wide range of techniques....

Gomphonema parvulum Kützing and morphologically similar species can be difficult to distinguish while differing markedly in their ecology. It is important to identify these species correctly if the ecological status of their habitats is to be assessed accurately. Here, two species in this group are documented using light and scanning electron micro...

Table S10. Size measurements (valve width and length) of diatom individuals sampled from the fourteen streams.

Plots showing a comparison of water chemistry in the Hengill streams to other sites. Figure S2. Photographs illustrating shape approximations of a diatom species with an unusual valve outline. Figure S3. Linear regression plots of temperature against log10 valve area for 31 diatom species that were present in at least 2 of the sampled streams. Figu...

Table S11. Count data for all diatom species found in each of the fourteen streams.

Four new small-celled naviculoid diatom species belonging to the genera Adlafia, Chamaepinnularia, Mayamaea, and Microcostatus were found during a survey of the non-marine diatom flora of the South Shetland Islands and James Ross Island (Maritime Antarctic Region). Following both light and scanning electron microscopy, the following species were de...

Climate warming has been linked to an apparent general decrease in body sizes of ectotherms, both across and within taxa, especially in aquatic systems. Smaller body size in warmer geographic regions has also been widely observed. Since body size is a fundamental determinant of many biological attributes, climate-warming-related changes in size cou...

Unicellular algae called diatoms morph biomineral compounds into tough exoskeletons via complex intracellular processes about which there is much to be learned. These exoskeletons feature a rich variety of structures from submicroscale to milliscale, many that have not been reproduced in vitro. In order to help understand this complex miniature mor...

This paper describes the results of long-term growth in culture of a clone of Gomphonema parvulum, which demonstrates that this taxon, unlike most other diatoms or other parts of G. parvulum, does not decrease in size as it reproduces vegetatively. After a period of eight months in culture, cells were significantly longer although valve widths were...

The analysis of a sample taken in a lava tube cave on Ile Amsterdam (southern Indian Ocean) revealed the presence of three interesting small-celled naviculoid diatom taxa. Based on light and detailed scanning electron microscopy, two of these taxa are described as new: Mayamaea cavernicola sp. nov. and Sellaphora barae sp. nov. A third taxon, Chama...

The ultrastructure of Diatomella balfouriana Greville collected from Île de la Possession, a sub-Antarctic island in the Crozet Archipelago, was studied using high-resolution scanning and transmission electron microscopy. The alveolate striae of the genus are subdivided by small vimines, presenting a unique feature never observed before in other di...

2012): Haslea karadagensis (Bacillariophyta): a second blue diatom, recorded from the Black Sea and producing a novel blue pigment, European Journal of Phycology, 47:4, 469-479 This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, syst...

The study of the blue diatoms from the genus Haslea is an arcane topic, due to investigations being restricted to the only species Haslea ostrearia (Gaillon/ Bory) Simonsen. This diatom, first observed in the early 19th century, has the peculiar ability to produce a non‐photosynthetic blue pigment, the so‐called marennine. This pigment’s name refer...

We present a number of promising examples of computational studies, which improve our understanding of the morphogenesis process of diatom cell walls. Each example considers a different physical scenario whereby computational and mathematical models are used to evaluate hypotheses pertaining to diatom valve formation; considering the roles of cytos...

The morphological plasticity and adaptive behavior exhibited during diatom colony formation in Aulacoseira is explored through computer simulation to study how the interplay of mechanisms such as cytoskeletal-driven membrane protrusions, silica deposition, and environmental factors may contribute to the generation of two distinct spine morphologies...

Spring Ecology

Springs are unique aquatic habitats that contribute significantly to local and regional biodiversity because of their high habitat complexity and the large number of different spring types. Many springs are small, but they are numerous and often of high water quality, and thus, provide habitats for species that are rare elsewhere because of their s...

Tursiocola podocnemicola sp. nov. is described from the Amazonian Rio Negro Basin in Brazil where it was found living epizoically on the carapaces of the freshwater turtle Podocnemis erythrocephala Spix. The detailed morphology of this epizoic diatom is examined using both light and scanning electron microscopy and compared with similar species of...

The type material of Nitzschia abbreviata Hustedt ex Simonsen (Nitzschia sect. Lanceolatae) has been examined with light and electron microscopy in order to clarify the structure and identity of this species which may have been largely neglected and possibly identifi ed as N. inconspicua Grunow or N. frustulum (Kützing) Grunow. We illustrate some o...

This article reviews current knowledge of wall morphogenesis in pennate diatoms in relation to the way characters are defined and described for taxonomic and systematic analyses. It argues that an understanding of ontogeny is essential for the accurate identification of character homologies, which in turn must underpin all phylogenetic and systemat...

The structure of a small marine planktonic centric diatom belonging to the genus Thalassiosira was characterised using electron microscopy; and data on its ultrastructure, autecology and initial valve formation are provided here. Although our specimens shared some characteristics with Thalassiosira proschkinae sensu lato, they differed from the typ...

The Breitenbach, probably the best-studied stream on earth, was the object of an unparalleled long term Ecosystem Study carried out from 1969 to 2006 by the Limnologische Fluss-Station Schlitz (Germany), part of the former Max Planck Institute for Limnology (now MPI for Evolutionary Biology). The focus of the book is on animal and microorganism pop...

Pinnularia is an ecologically important and species-rich genus of freshwater diatoms (Bacillariophyceae) showing considerable variation in frustule morphology. Interspecific evolutionary relationships were inferred for 36 Pinnularia taxa using a five-locus dataset. A range of fossil taxa, including newly discovered Middle Eocene forms of Pinnularia...

As part of a study on the diatom flora of the Gokyo Valley, Everest National Park, Nepal, eleven species of Cymbopleura (Bacillariophyta), including two new species, Cymbopleura gokyoensis Jüttner et Van de Vijver sp. nov. and Cymbopleura emoda Jüttner et Van de Vijver sp. nov., were investigated using light and electron microscopy. Some taxa could...

This chapter provides an overview of diatom wall construction, morphology (light microscopy [LM]), and structure (electron microscopy [EM]), cell cytology, and aspects of wall morphogenesis. It also seeks to highlight areas where more information is required, while stressing the importance of applying descriptive terminology appropriately and consi...

Species of the genus Achnanthidium including Achnanthidium pyrenaicum (Hustedt) Kobayasi and morphologically similar taxa are common and abundant in streams of the Himalaya in Nepal and north-west India. They were investigated with respect to their morphology and ecology, exploring their response to gradients in altitude, water chemistry, habitat c...

Following the discovery of specimens resembling Achnanthes pseudoconspicua, the type slide of this species was investigated. The latter contained very few valves, which were documented with light microscopy. Specimens from streams and ponds of central and eastern Nepal conformed to the original diagnosis and were investigated using light and electr...

The effects of salinity on the growth and valve morphology of five benthic estuarine diatoms (Nitzschia pusilla, N. frustulum, N. palea, N. filiformis var. conferta and Eolimna subminuscula), isolated from both freshwater and brackish/marine habitats, were investigated. The four Nitzschia strains grew well over a broad salinity range, though some (...

Background – Diatoms are unicellular algae, prolific in nearly all aqueous environments on earth. They are encased between two siliceous valves that each feature a variety of intricately patterned species-specific siliceous structures. How diatoms use biological and physical processes to form these tiny detailed structures is largely unknown. This...

Background - The traditional approach to diatom systematics assumed that structure and morphology were stable within a taxon and replicated faithfully down the generations, but wall structure is the end-product of biological processes, potentially modified by environment and over time. Electron microscopy revealed additional structural characters t...

A new genus Oricymba is described with its type species based on Cymbella japonica Reichelt. In addition, three new species are described from the Nepalese Himalaya: O. subaequalis, O. latirotundata and O. subovalis. The new genus has slightly dorsiventral or almost symmetrical valves with polar raphe endings deflected to the dorsal side. It can be...

Himalayan streams, an important natural resource, are subject to numerous threats such as pollution and hydrological changes with deteriorating water quality in some areas. In order to develop diatom-based monitoring tools, we investigated diatom species composition at 206 sites in relation to variation in hydrochemistry, habitat characteristics (l...

A previously unidentified, small, centric diatom from Cappadocia, Central Turkey is described as a new species and genus (Clipeoparvus anatolicus). Cells of this diatom are sub-spherical, often linked in pairs and covered with irregular spines. Striae radiate around a hyaline area on the valve face. Neither rimoportulae nor fultoportulae were found...

Nilzschia palea (Kiltzing) W. Smith is believed to be a widely distributed diatom and is common in various lotic and lentic freshwater habitats. However, it is also taxonomically problematic. As part of a multidisciplinary study of this diatom, 25 clones identified morphologically its N. palea were isolated from different freshwater habitats around...

Large numbers of diatom taxa are currently being described each year and molecular data sets are providing phylogenetic evidence that challenges the traditional systematic ar-rangement of diatoms, but is such information being integrated into the classification? The traditional diatom classification originated as an aid to identification rather tha...

A technique for obtaining cross-sections of diatom frustules which retains the integrity of the frustule without recourse to an ultra-microtome and allows their examination under SEM is described. The technique employs the polishing and etching of resin-embedded material and can be applied to cleaned diatoms from field samples or cultures. Examples...

Two closely related species of the diatom genus Navicula were investigated using light and electron microscopy. A hitherto unrecorded structure associated with the raphe of N. delognei Van Heurck is described. Examination of type material revealed that the nomenclatural types of N. grevillii (CA.Ag.) Heiberg and N. comoides (Dillwyn) H. & M. Peraga...

Colonies of Berkeleya rutilans (Trent.) Grun., Navicula pseudocomoides Hendey and N. ramosissima (C. A. Ag.) Cleve were examined using light and electron microscopy to elucidate the structure of their mucilage tubes. Each species was found to have a characteristic tube construction which could be used for identification. A summary of features on wh...

Diatoms have traditionally been identified on the basis of wall morphology, many species having been described from single gatherings over 150 years ago. Names were often based on a very small part of the organism's morphological range, concepts often being subsequently broadened by inference based on perceived similarity. However, comparison of sp...

Nitzschia fonticola (Grunow) Grunow is a member of Nitzschia sect. Lanceolatae, a group of taxonomically intractable but ecologically important and widespread diatoms. We investigated the morphology and life cycle in three clones of N. fonticola and all exhibited reduced sexuality, with pedogamous production of auxospores in unpaired gametangia. Th...

The relationships between 49 naviculoid diatoms, currently arranged in 14 families and four orders were investigated using cladistic analysis in order to test the types of characters used in diatom systematics and to assess how well the current classification reflects possible phylogenetic relationships in this group. Some of the families and order...

Despite variation in their protoplast organization and wall structure, monoraphid diatoms have traditionally been grouped as a single family or order, intermediate between the araphid and biraphid diatoms. However, the predominantly marine or brackish species of Achnanthes sensu stricto share protoplast and frustule features with representatives of...

Diadesmis gallica is unusual in producing two contrasting valve morphologies, one with a raphe system and non-spiny valves, the second without a raphe system but with peripheral linking spines. The latter valve morphology is associated with colony formation. Valve development is described, with particular attention to spine formation and raphe loss...

The diatom assemblages within phototrophic biofilms in secondary treatment tanks of the Fiumicino Airport (Rome, Italy) wastewater treatment plant were investigated. Qualitative and quantitative comparisons were made between assemblages in sedimentation and chlorination tanks, on the tank walls and artificial substrata, on four sampling occasions....

Achnanthes was described by Bory to include three species, A. adnata, A. dubia and A. baccillarioides, formerly included under Echinella stipitata Lyngbye. Boyer typified the genus Achnanthes using A. adnata and this typification has been accepted by subsequent authors. However no extant material of A. adnata is known. Since this species was based...

Nitzschia fonticola (Grunow) Grunow is a member of Nitzschia sect. Lanceolatae, a group of taxonom-ically intractable but ecologically important and widespread diatoms. We investigated the morphology and life cycle in three clones of N. fonticola and all exhibited reduced sexuality, with pedogamous production of auxospores in unpaired gametangia. T...