A new species of Colura (Lejeuneaceae) from the Aberdare Mountains, Kenya

The new species Colura zoophaga from the Aberdare Mountains in Kenya is described as new. It differs from C. berghenii and C. hedbergiana in the obtuse apex, which is rounded or only weakly prolonged. C. zoophaga also differs from C. berghenii in the smooth leaf-cells, from C. hedbergiana in the 5-horned perianth keels and from C. calyptrifolia in the papillose perianth. A key to the African taxa of Sectio Macroramphus is provided. The ecology of C. zoophaga is briefly described

Taxonomic results of the Bryotrop expedition to Zaire and Rwanda : 4., a preliminary check-list of the Hepaticae and Anthocerotae from Central Africa (Zaire, Rwanda, Burundi)

A check-list of the Hepaticae and Anthocerotae from Central Africa (Zaire, Rwanda, Burundi) is presented. 267 liverwort species and 4 hornworts are recognized for the area. For Zaire 215 Hepaticae and 3 species of Anthocerotae are recorded. In Rwanda 150 liverworts and one hornwort have been found. Burundi is far less known and only 48 Hepaticae are recorded

Taxonomic results of the Bryotrop expedition to Zaire and Rwanda : 2., history of bryological exploration of Zaire and Rwanda

A short survey of the bryological exploration of Rwanda and Zaire is provided. The first to collect bryophytes in the area was Stuhlmann in 1891 on Ruwenzori. The first bryological collections from Rwanda were made by Mildbraed in 1907. In 1929 Humbert made the first gatherings on Mt. Kahuzi and Mt. Biega. Since then a lot of botanist have collected mosses and liverworts so that Rwanda and eastern Zaire can be regarded as well known. From most parts of Zaire and from Burundi however only few data are hitherto available

Taxonomic results of the Bryotrop expedition to Zaire and Rwanda : 3., description of dollecting sites, the vegetation of Kahuzi-Biega-National Park/Zaire, Nyungwe Forest and Virunga volcanoes/Rwanda

During the BRYOTROP-Expedition in 1991, 71 collecting sites could be visited. These are situated in the Kahuzi-Biega-National Park/Zaire, the Nyungwe Forest and the Virunga volcanoes/Rwanda. This paper provides a short description of the vegetation in these three areas and a detailed list of all collecting sites

Taxonomic results of the Bryotrop expedition to Zaire and Rwanda : 10., Trichocoleaceae, Geocalycaceae, Acrobolbaceae, Balantiopsidaceae, Lepidoziaceae (Telaranea, Arachniopsis), Calypogeiaceae, Adelanthaceae, Porellaceae, Jubulaceae, Marchantiaceae (Dumortiera), Polytrichaceae

A survey of the families Trichocoleaceae, Geocalycaceae, Acrobolbaceae, Balantiopsidaceae, Lepidoziaceae (Telaranea, Arachniopsis), Calypogeiaceae, Adelanthaceae, Porellaceae, Jubulaceae, Marchantiaceae (Dumortiera) (Hepaticae) and Polytrichaceae (Musci) for Central Africa (Zaire and Rwanda) is presented. Leptoscyphus infuscatus, Tylimanthus ruwenzoriensis, Calypogeia fissa, Adelanthus lindenbergianus and Porella subdentata are recorded as new to Rwanda. Telaranea trifida and Calypogeia fusca are new to Zaire. Leptoscyphus hedbergii and Calypogeia afrocaerulea are new records for Zaire and Rwanda

Taxonomic results of the Bryotrop expedition to Zaire and Rwanda : 8., Riccia vulcanicola E. Fischer (subgenus Ricciella, Sectio Cavernosae), a new species from the Virunga Volcanoes, Rwanda

A new Riccia species, R. vulcanicola is described and illustrated. It is closely related to R. crystallina, differing by the incomplete rosettes of the thallus and the larger and fewer areolae of the spores.Une espèce nouvelle du genre Riccia, R. vulcanicola, est décrite. Elle est relée à R. crystallina, mais se distingue par les rosettes incompléttes du thalle et par les aréoles plus grandes et moins nombreuses des spores

Scientific results of the Bryotrop expedition to Zaire and Rwanda : 3., photosynthetic gas exchange of bryophytes from different forest types in eastern Central Africa.

During the BRYOTROP-Expedition to Zaire and Rwanda bryophytes were collected from a rainforest habitat at 800 m a.s.l. and from bamboo forest and tree-heath environments between 2200 and 3200 m. The microclimates influencing the mosses are different at the altitudinally separated locations. Conditions are rather constant with 24 °C, 100 % rel. hum. and PAR below 100 μmol photons m-2 sec-1 at the lowland station, rather versatile in the mountains with six times higher daily sums of PAR, temperatures between 10 and 25 °C and relative humidities between 60 and 1oo %. In the bamboo forest epiphytic mosses dry out during the day to less than 70 % of their water content, but regain saturation from the vapor-saturated air during night. Bryophyte photosynthesis and respiration were studied by Warburg manometry with moisture saturated samples. Temperature curves of gas exchange peaked between 22 and 30 °C. Optima of the lowland species were somewhat higher than those from samples collected at the mountain sites. Habitat separation of characteristics of photosynthesis was more pronounced with respect to light responses. Saturation gas exchange rates were reached by all species still below 400 μmol photons m-2 sec-1. But the slopes of the curves in the low-light range were distinctly steeper, and the light compensation points smaller in the lowland than in the highland species (compensation points of the former: 3 - 12 μmol photons m-2 sec-1, of the latter: 8 - 20 μmol photons m-2 sec-1). It is emphasized that bryophytes in the rainforest understory experience extremely high ambient C02 concentrations near the floor. This, their low light requirements for photosynthesis, and the permanently optimal temperature and humidity conditions for maximal carbon gain enable them to live successfully, but with less biomass development in this dark and damp environment. By contrast, bryophytes from the bamboo forest and tree-heath environments can utilize light conditions combined with variable temperatures and humidities similarly as species from extratropical vegetation types

Bryophytes from the Cape Verde Islands

Almost 450 specimens of bryophytes, so far the largest collection of bryophytes ever made on the Cape Verde Islands, were collected in 1995 by the second author on the major islands of the archipelago. Twenty seven species (3 hepatics, 24 mosses) are reported as new to the Cape Verde Islands: Lejeunea ulicina (Tayl.) Gottsche et al., Riccia cavernosa Hoffm. emend. Raddi, Targionia hypophylla L., Barbula cf. consanguinea (Thwait. & Mitt.) Jaeg., Barbula unguiculata Hedw., Brachymenium exile (Dozy & Molk.) Bosch. & Lac., Bryoerythrophyllum ferruginascens (Stirt.) Giac., Bryoerythrophyllum inaequalifolium (Tayl.) Zander, Bryum cellulare Hook., Chenia leptophylla (C. Müll.) Zander, Desmatodon bogosicus C. Müll., Didymodon australasiae (Hook. & Grev.) Zander, Didymodon maschalogena (Ren. & Card.) Broth. (Didymodon michiganensis [Steere] K. Saito), Didymodon vinealis (Brid.) Zander var. flaccidus (B.S.G.) Zander, Eurhynchium meridionale (B.S.G.) De Not., Eurhynchium speciosum (Brid.) Jur., Fissidens sciophyllus Mitt., F. bogosicus C. Müll., F. flaccidus Mitt., F. helictocaulos C. Müll., Gymnostomiella cf. vernicosa (Hook.) Fleisch., Gymnostomum calcareum Nees & Hornsch., Hyophila involuta (Hook.) Jaeg., Orthotrichum diaphanum Brid., Tortula cuneifolia (With.) Turn., Tortula laevipila (Brid.) Schwaegr. and Weissia microstoma (Hedw.) C. Müll. The doubtful record of Marchantia paleacea Bertol. could be confirmed. Numerous species are recorded as new to single islands. Tortula pierrotii Biz. described from Tanzania has proved to be synyomous with Bryoerythrophyllum inaequalifolium. Didymodon maschalogena (Ren. & Card.) Broth. is an older name for Didymodon michiganensis (Steere) K. Saito. A study of types of species described as endemic to the Cape Verde Islands revealed that Barbula bolleana (C. Müll.) Broth. is an earlier name for Hydrogonium bolleanum (C. Müll.) Jaeg., Barbula elliottii Broth., Barbula kivuensis Leroy & P. de la Varde and Barbula madagassa Ren. & Card. are synonymous with the latter, Hyophila crenulata C. Müll. ex Dus. var. brevifolia Bizot is synonymous with Hyophila involuta (Hook.), Barbula sulcata Geh. is synonymous with B. convoluta Hedw. and Tortula subcaroliniana Bizot is synonymous with Tortula amphidiacea (C. Müll.) Broth. In addition to the so far unpublished results of recent collections, a complete survey of the bryophyte flora of the Cape Verde Islands is given. A hundred and sixty two species (2 species of hornworts, 36 species of hepatics and 124 species of mosses) are so far known from this archipelago

Experimental investigations on impact transmission through a plate

The concept of an impact actuated shift valve is presented. This valve concept can be actuated by different kinds of actuators, such as piezo stack actuators. A simplified model for the investigation of the impact process is created. The model consists of a plate, two spheres and a fluid-filled tank. Experiments are presented with and without fluids and different plates. The results are compared to simulations

Simulation of a micro shift valve with impact actuation

A new concept of an impact actuated micro shift valve is presented. The impacts are transmitted to the interior of the valve through the casing. In order to predict the energy transmitted into the valve, the most important effects are discussed and two elastic multibody models using the Hertzian contact law are introduced and compared to a full finite element simulation. A simpler model with one degree of freedom for an elastic plate as transmission element proves to be too crude. But a more sophisticated model with axisymmetric finite elements for the plate shows good agreement. The simulations are compared to experiments performed with a scaled model for two different cases. The experiments show that so far neglected effects like plastic deformation occur and must be considered in the simulation if accurate predictions are required