Browsing by Autor "Lucien Hoffmann"

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Analysis of the type of Fragilaria construens var. subsalina (Bacillariophyceae) and description of two morphologically related taxa from Europe and the United States
(Taylor & Francis, 2011) Cristina Cejudo‐Figueiras; Eduardo A. Morales; Carlos E. Wetzel; Saúl Blanco; Lucien Hoffmann; Luc Éctor
Cejudo-Figueiras C., Morales E.A., Wetzel C.E., Blanco S., Hoffmann L. and Ector L. 2011. Analysis of the type of Fragilaria construens var. subsalina (Bacillariophyceae) and description of two morphologically related taxa from Europe and the United States. Phycologia 50: 67–77. DOI: 10.2216/09-40.1Fragilaria construens var. subsalina is a common diatom found in a wide variety of aquatic systems worldwide. It was described by Hustedt (1925) Hustedt F. 1925. Bacillariales aus den Salzgewässern bei Oldesloe in Holstein. Mitteilungen der Geographischen Gesellschaft und des Naturhistorischen Museums in Lübeck, 2. Reihe, Heft 30: 84–121. [Google Scholar] from brackish waters in Oldesloe, Germany; a lectotype specimen was established by Simonsen (1987) Simonsen R. 1987. Atlas and catalogue of the diatom types of Friederich Hustedt. J. Cramer, Berlin - Stuttgart. Vol. 1 (catalogue). 525 pp. Vol. 2, 597 pp., pls 1–395; Vol. 3, 619 pp., pls 396–772. [Google Scholar]. We analysed the ultrastructure of specimens from the lectotype material by means of light (LM) and scanning electron microscopy (SEM) and show that this taxon should be placed at the species level within the genus Pseudostaurosira (as Pseudostaurosira subsalina). A similar but distinct taxon from the United States, found in waters with low electrolyte content, is proposed as a new species of Pseudostaurosira, namely Pseudostaurosira americana sp. nov. We also describe a second new species from Spain (Pseudostaurosira alvareziae sp. nov.), found in waters with moderate conductivity, which was misidentified as P. subsalina in the past. A morphometric analysis of the valve shape supports the morphological separation between the three species. The present study clarifies the taxonomy, ecology and systematic position of these three taxa and provides a comparison with other, similar taxa.
Diatoms (Bacillariophyceae) from the Bolivian Altiplano: three new araphid species from the Desaguadero River draining Lake Titicaca.
(Česká algologická společnost, 2012) Eduardo A. Morales; María Helena Novais; Gabriela Chávez; Lucien Hoffmann; Luc Éctor
Three new araphid diatom species, Pseudostaurosira decipiens E. Morales, G. Chávez et Ector, P. sajamaensis E. Morales et Ector and Staurosira kjotsunarum E. Morales, Novais et Ector are described from a single sample taken from the Desaguadero River in the Bolivian Altiplano. These species clearly belong in their respective genera as evidenced by their morphological features studied using light (LM) and scanning electron microscopy (SEM). Pseudostaurosira decipiens is unique in its genus because of the combination of lanceolate-shaped valves with central area, well-developed spines lacking ligulae, siliceous deposits on outer and inner areolar openings similar to flaps, and the inner rounded structure of the apical pore fields. Pseudostaurosira sajamaensis is different from other species of Pseudostaurosira due to its elliptic to lanceolate valves bearing a wide central sternum, spines with developed ligulae and bilobed flaps, robust volae and reduced or absent apical pore fields. Staurosira kjotsunarum is unique within Staurosira in having elevated costae on both external and internal views, narrowly spatulate spines that hold onto areolae of neighboring valves along a chain, and striae composed of round poroids underneath the apical pore fields on the valve mantle. The three species are compared with morphologically similar taxa and a brief analysis of the richness found in the studied sample in the context of previous publications on diatoms from the Andes and contiguous regions is presented.
New epiphytic araphid diatoms in the genus Ulnaria (Bacillariophyta) from Lake Titicaca, Bolivia
(Taylor & Francis, 2013) Eduardo A. Morales; Sinziana F. Rivera; Carlos E. Wetzel; María Helena Novais; Paul B. Hamilton; Lucien Hoffmann; Luc Éctor
Two new epiphytic species of Ulnaria (Kützing) Compère, U. titicacaensis E. Morales, Ector & P.B. Hamilton and U. macilenta E. Morales, C.E. Wetzel & S.F. Rivera, are described from the Tiquina Strait, Lake Titicaca, Bolivia. The taxa have distinctive morphological features and their separation from morphologically related taxa and from each other is predominantly based on features of the valve central area and type of colonies. Whereas most morphologically similar taxa have a clear unilateral central area and form ribbon-like colonies, U. titicacaensis has a central area which is large and depressed internally, square to rectangular fascia, forms pin-cushion-like colonies mainly on Cladophora species, and has large polyphosphate bodies located toward the frustule apices. In contrast, U. macilenta has a similar central area to that in U. titicacaensis, but has narrower valves, forms short palisade groupings arranged in pin-cushion-like colonies, mainly on Oedogonium species and has polyphosphate bodies distributed throughout the frustule lumen. Morphological and ecological aspects of both new taxa are discussed in the light of available literature.
Transfer of Staurosira grunowii to Staurosirella
(Taylor & Francis, 2013) Eduardo A. Morales; Krisztina Buczkó; Carlos E. Wetzel; María Helena Novais; Nadja Ognjanova‐Rumenova; Lucien Hoffmann; Luc Éctor
The new combination Staurosirella grunowii (Pantocsek) E. Morales, Buczkó & Ector comb. nov. is presented based on a detailed analysis of fossil material from Lutila, Slovakia using light and scanning electron microscopy. The species is widely known as Staurosira harrisonii var. amphitetras Grunow. Striae bearing well-developed vimines delimiting typically long areolae, thick virgae-bearing spines, developed apical pore fields composed of simple round poroids and open girdle bands with valvocopula-bearing fimbriae are some of the features that link this taxon to species currently ascribed to Staurosirella D.M. Williams & Round. The taxon is readily distinguished by its tetra-angular shape, which is not seen in any other species within this genus. An analysis of the morphology of this taxon together with its nomenclatural history is presented herein.