A focus on Pycreus and its laterally flattened pistils: the challenging taxonomy and evolution of C4 Cyperus (Cyperaceae)

Cypereae form one of the largest and most complex tribes of the sedge family (Cyperaceae). Recently, two clades have been revealed within the tribe, the largest of which includes the giant genus Cyperus and its closest allies. However, thirteen genera of the generally accepted classification of Goetghebeur (1998) appear to be nested within Cyperus. The taxonomic status of many of these taxa has been under discussion since they are based on different combinations of a limited set of derived characters. Pycreus, the largest of these segregate genera, is characterised by laterally compressed dimerous pistils of which the derivation from the general trimerous situation was not yet understood. It shares this pistil with Kyllinga and Queenslandiella that both are, as is Pycreus, embedded in the Cyperus clade which uses C4 photosynthesis. The recent insights from molecular phylogenetics make a reevaluation possible of the taxonomic status of the thirteen different segregate genera of Cyperus and of the taxonomic value of the characteristics that have been used to delimitate these taxa. This is currently tackled in a joint international research effort, using a combination of molecular phylogenetics, ontogeny, anatomy and morphology, to understand evolutionary patterns in Cyperaceae and to build a modern classification of sedges. This research strategy is situated on three taxonomic levels: family to tribal level (macro-scale), tribal to generic level (meso-scale) and infrageneric level (micro-scale). The current thesis is embedded in this international research context and focusses mainly on meso-scale objectives (C4 Cyperus and the position and taxonomic state of its segregate genera, including Pycreus) and micro-scale objectives (the infrageneric taxonomy of Pycreus). At first, a complete nomenclatural survey is presented of all generic and subdivisional names that have been published for the taxa now included in the Cyperus clade (around 350 names), along with an evaluation of their validity, legitimacy and priority. Types are indicated and where necessary lectotypes are designated. This nomenclatural survey serves as a base for the selection of representative taxa in the molecular, ontogenetic, anatomical and morphological studies. In addition it forms an essential tool when building a modern revision for the clade. In the current thesis only names for taxa in which Pycreus species have been placed are included. Next, to be able to reevaluate the taxonomical value of derived pistils in the Cyperus clade, especially the laterally compressed dimerous pistils of Pycreus, an elaborate ontogenetic study of Pycreus and Cyperus species was performed. This study shows that both taxa follow the general ontogenetic patterns of spikelets and flowers found throughout Cyperoideae. In addition, the ontogeny and anatomy of the different types of pistils was reviewed with addition of new ontogenetic and anatomical data. These demonstrate that in Cyperoideae the pistil wall starts from an annular primordium (which evolved from congenitally fused carpels) on top of which the stigma primordia develop. The development of the central ovule is decoupled from the ovary wall development. Vascular patterns follow the development of the primordia and vascular bundles are formed where necessary. The presence of an annular gynoecial wall primordium appears to have opened new possibilities for the development of the stigma primordia in new positions independent from the constraints of individual carpels. An elaborate molecular phylogenetic study was performed on the C4 Cyperus clade using ETS1f, rpl32-trnL, trnH-psbA. Although relationships within the C4 Cyperus clade are still largely unresolved in a large polytomy, early emerging branches show better resolution than in previous studies. Pycreus appears to be para- or polyphyletic and in addition no relationships have been found between Pycreus, Kyllinga and Queenslandiella. Therefore, we have to admit, laterally compressed dimerous pistils have most likely originated multiple times in the clade. Subsequently, the most appropriate classification strategy for these taxa is sinking them into Cyperus. This also seems to be the most appropriate strategy for all other segregate genera based on a reevaluation of the taxonomical value of their key characters. Only for the C4 Cyperus clade (accommodated in C. subgenus Cyperus), which is nested within a grade of species using C3 photosynthesis (accommodated in C. subgenus Anosporum), an evolutionary classification strategy has been adopted. This is based on the evolutionary value of the origin of C4 photosynthesis which had led to a major radiation of species. On the micro-scale, it is not yet possible to present a modern classification for Pycreus since molecular phylogenetic relationships are largely unresolved. Therefore, results are presented as several case studies. First, in an elaborate SEM study, the taxonomical value of the nutlet epidermis was reevaluated. Next, the reestablishment of P. sect. Tuberculati is discussed. Finally, the new classification strategy for the Cyperus clade was applied on Pycreus and necessary combinations and nomina nova under Cyperus are listed along with some critical notes on synonymisations of several taxa

Two new species of Cyperus (Cyperaceae) from the Zambezian region of Africa

Cyperus absconditicoronatus Banters, Reynders & Goetgh. and C. unispicatus Banters, Reynders & Goetgh., two new species of Cyperus L. (Cyperaceae) from Angola and Zambia, are recognized. Cyperus absconditicoronatus is a tall species (55-100 cm) characterized by a scaled rhizome, a single terminal capitulum, a ciliated spikelet bract, and deciduous spikelets. Cyperus unispicatus can be recognized by a swollen and fibrous stem base growing from slender rhizomes, a single terminal spike, and short involucral bracts. The taxa are described and illustrated, and differences with the closest resembling species are discussed

Studies on growth, modelling and pigment production by the yeast Phaffia rhodozyma

Bibliography: pages 117-123.Within the aquaculture industry a potential has been identified for the pigment astaxanthin. Astaxanthin is the carotenoid responsible for the distinctive coloration of salmonids, crustaceans and certain birds. Due to the fact that animals cannot synthesize carotenoids themselves, it is necessary for these pigments to be present in their food source. In the case of farm-raised salmonids and crustaceans, supplementation of their food with astaxanthin is required. The chemical synthesis of astaxanthin is very costly and complicated. As a result natural, microbial sources of astaxanthin are being investigated. Phaffia rhodozyma is the only yeast known to synthesize astaxanthin as its principle carotenoid. The aim of this dissertation is to present a study investigating the growth and pigmentation of P. rhodozyma, with a view to its commercial production. A P. rhodozyma mutant (UCT-1 N-3693) with a 50% increased total carotenoid content was selected after NTG mutagenesis of the wild strain

Thomas Edward Brown\u27s narrative poetry

This thesis presents a study ot the narrative poetry of Thomas Edward Brown. A sincere effort has been made to keep the original aspects of the study free from those prejudices which spring from an admiration for a writer like Brown. My aim has bean to stress those aspect of Brawn\u27s narrative work upon which he claim or distinction as a writer or narrative poetry depend

Modeling reinforcement structures in textile aimed at biomechanical purposes

While sporting, muscles, tendons and the body in general come under extreme loads which may lead to wrong movements and injuries which impact the performance or lead to mandatory rest. As athletes often wear compression garments, we investigate how reinforcement structures such as elastic bands, yarns or fabric strips with a given pretension, or rigid structures can be added to compression garments to prevent incorrect sport movements. This paper discusses how an existing simulation tool (DySiFil) can be adapted to be able to extract supportive forces and pressures and validates the findings for the case of overextension of the fingers and the thumb

A fossil Chimaeroid from the Gronsveld Member (Late Maastrichtian , Late Cretaceous)of northeast Belgium

The associated fragments of a single male individual of a large chimaeroid fish are described from the Gronsveld Member (LateMaastrichtian, LateCretaceous) of Romontbos Quarry in northeast Belgium. The material includes a complete dorsal fin spine, tooth plate fragments and frontal clasper denticles. The arrangement of the tritors on the tooth plates indicates that the specimen belongs to Edaphodon sp., having closest similarity with E.agassizi and E.ubaghsi. Chimaeroid frontal clasper denticles are figured and described in detail for the first time, with the development of an appropriate terminology. Clasper denticles are arranged in a closely fitting revetment of longitudinal and diagonal rows, with a consistent pattern of base overlap. Edaphodon clasper denticles differ from those of extant chimaeroids in various features of the base. Clasper denticle morphology is a potentially useful taxonomic tool at the suprafamilial level. Attachment of posterolateral denticles to the dorsal fin spine was secondary, and proceeded in an apical direction. Anterior dorsal fin spine denticles are primary features of spine development in Edaphodon. Bloodvessel tracery is described from the lateral walls of the spine. Dorsal fin spine morphology appears to be taxonomically useful at the generic level

Dilational Viscosity of Langmuir monolayers

The dilational viscosity $\epsilon'$ of Langmuir monolayer is considered in a theoretical model taking into account an orientational effect of the dilational wave on surface molecules. This orientational order is described by the surface order parameter Q; the orientational part of the free surface energy is given by Landau's expansion in powers of Q. The magnitude of surface viscosity, driven by the surface tension derivative $\partial\gamma/\partial Q$, is in good accord with the experimentally observed $\epsilon'$. The sign of $\epsilon'$ is positive that indicates that increased in-plane ordering increases the surface tension.Comment: 11 pages, 2 Postscript figures, submitted to Physica A (September 1998