Showing papers in "Plant Ecology and Evolution in 2010"

A preliminary multi gene phylogeny of the diatoms (Bacillariophyta): Challenges for future research

Abstract: 1Texas Natural Science Center, 2400 Trinity Street, University of Texas, Austin TX 78619, U.S.A. 2Section of Integrative Biology, The University of Texas at Austin, 1 University Station (A6700), Austin, TX 78712, U.S.A. 3Plant Biology Graduate Program, The University of Texas at Austin, 1 University Station (A6700), Austin, TX 78712, U.S.A. 4Institute of Cellular and Molecular Biology, The University of Texas at Austin, 1 University Station (A6700), Austin, TX 78712, U.S.A. *Author for correspondence: etheriot@austin.utexas.edu

Phylogeny and circumscription of Sapindaceae revisited: molecular sequence data, morphology and biogeography support recognition of a new family, Xanthoceraceae.

Abstract: Background and aims Recent studies have adopted a broad definition of Sapindaceae that includes taxa traditionally placed in Aceraceae and Hippocastanaceae, achieving monophyly but yielding a family difficult to characterize and for which no obvious morphological synapomorphy exists. This expanded circumscription was necessitated by the finding that the monotypic, temperate Asian genus Xanthoceras, historically placed in Sapindaceae tribe Harpullieae, is basal within the group. Here we seek to clarify the relationships of Xanthoceras based on phylogenetic analyses using a dataset encompassing nearly 3/4 of sapindaceous genera, comparing the results with information from morphology and biogeography, in particular with respect to the other taxa placed in Harpullieae. We then re-examine the appropriateness of maintaining the current broad, morphologically heterogeneous definition of Sapindaceae and explore the advantages of an alternative family circumscription. Methods Using 243 samples representing 104 of the 142 currently recognized genera of Sapindaceae s. lat. (including all in Harpullieae), sequence data were analyzed for nuclear (ITS) and plastid (matK, rpoB, trnD-trnT, trnK-matK, trnL-trnF and trnS-trnG) markers, adopting the methodology of a recent family-wide study, performing single-gene and total evidence analyses based on maximum likelihood (ML) and maximum parsimony (MP) criteria, and applying heuristic searches developed for large datasets, viz, a new strategy implemented in RAxML (for ML) and the parsimony ratchet (for MP). Bootstrap analyses were performed for each method to test for congruence between markers. Key results Our findings support earlier suggestions that Harpullieae are polyphyletic: Xanthoceras is confirmed as sister to all other sampled taxa of Sapindaceae s. lat.; the remaining members belong to three other clades within Sapindaceae s. lat., two of which correspond respectively to the groups traditionally treated as Aceraceae and Hippocastanaceae, together forming a clade sister to the largely tropical Sapindaceae s. str., which is monophyletic and morphologically coherent provided Xanthoceras is excluded. Conclusion To overcome the difficulties of a broadly circumscribed Sapindaceae, we resurrect the historically recognized temperate families Aceraceae and Hippocastanaceae, and describe a new family, Xanthoceraceae, thus adopting a monophyletic and easily characterized circumscription of Sapindaceae nearly identical to that used for over a century.

Copper endemism in the Congolese flora: a database of copper affinity and conservational value of cuprophytes

Abstract: Background and aims - The occurrence of natural plant communities on Cuenriched substrates over significant areas of the earth's surface is exceptional. In Katanga (D.R.Congo), natural outcrops of copper-rich rocks are colonised by highly original plant communities. A number of plant species have been proposed as possibly endemic to those sites. Here we revise the taxonomic, phytogeographic and conservational status of these plants. Methods - Almost all the herbarium materials of supposed Cuendemics available in BR and BRLU have been revised and all relevant taxonomic revisions have been consulted. Literature and herbarium data have been supplemented by original observations in the field. Conservational status was established using IUCN criteria based on current and projected variation of population size and number. Key results - Thirty-two taxa are identified as strict endemics of Curich soil in Katanga, i.e. absolute metallophytes. Twenty-four of these are known from one to five localities only. Twenty-three other taxa are identified as broad endemics, i.e. with > 75% of occurrence on Curich soil. Fifty-seven other names formerly used for supposed endemics are rejected either for nomenclatural or phytogeographic reasons. A number of species formerly regarded as endemics have been discovered off copperenriched substrates due to progress in the botanical exploration of Katanga. The taxonomic value of a number of proposed endemics is still uncertain and requires further research. For a number of taxa, local geographic distribution still remains insufficiently known. The low proportion of endemics (c. 5%) in the flora of Curich soil in Katanga possibly indicates a recent origin of much of this flora. Arguments in favour of neoendemism and relictual endemism, respectively, are discussed briefly. Ten percent of strict endemics are extinct and 65% are critically endangered, due to actual or projected habitat destruction by copper mining. Endemics restricted to primary habitats may be the most difficult to conserve. Several species, mostly annuals, are able to thrive on secondary metalliferous habitats created by the mining industry and may thus be at lower risk. Conclusions - This review emphasizes the high conservation value of the flora of Curich soil in Katanga and should help prioritise future conservation efforts. © 2010 National Botanic Garden of Belgium and Royal Botanical Society of Belgium.

Diversity of subaerial algae and cyanobacteria growing on bark and wood in the lowland tropical forests of Singapore

Abstract: Background and aims - Knowledge on diversity and distribution of algae and cyanobacteria in subaerial habitats still lags behind those of freshwater and marine environments. Notably, data on diversity of microalgae in tropical corticolous habitats are still scarce. We investigated species composition of subaerial epixylic algae and cyanobacteria from two Singaporean rainforest localities. We asked whether there are differences in species composition and alpha-diversity of samples taken in different areas and in different habitat types (bark vs. decaying bare wood). In addition, we asked whether there are differences in species turnover (beta-diversity) among different habitat types and areas. Methods - The cultivation-based approach and the microscopic analysis of populations were used. In total, 20 samples of bark and decaying wood from two forested areas were analyzed. Statistical analyses involved the non-metric multidimensional scaling (NMDS) of species data. Significance of differences in algal composition between groups of samples was evaluated by the non-parametric two-way ANOSIM (Analysis of Similarities) using the crossed design with permutations in blocks. The SIMPER method was used to identify species that characteristically discriminate between habitat types and sampling areas. Key results - In total, 57 species were identified. Green algae (Trebouxiophyceae, Chlorophyceae, Trentepohliales) were dominant, and Cyanobacteria were the second most frequent group. The dominants of the subaerial assemblages differed from corresponding temperate habitats and, in addition, their alpha-diversity was considerably higher. Several green algal morphospecies were characteristic for the bark localities (e.g. Dictyochloropsis spp., Pseudomarvania aerophytica, Printzina effusa and Printzina lagenifera). The alpha-diversity was similar in both habitat types, but the species turnover among samples (beta-diversity) was significantly higher in the decaying wood samples. Conclusions - Tropical corticolous habitats probably harbour higher diversity than corresponding temperate habitats. High beta-diversity of decaying wood illustrates general importance of this substrate for biodiversity of subaerial algae in the tropics.

Revision of the genus Hantzschia (Bacillariophyceae) Eunotia on Livingston Island (South Shetland Islands, Southern Atlantic Ocean)

Abstract: Diatoms (Bacillariophyta) are one of the most abundant groups of micro-algae present in the Antarctic Region, both in terms of number of species and of number of individuals (Jones 1996, Van de Vijver & Beyens 1999). The past ten years, the taxonomy of the Antarctic non-marine diatom flora has been thoroughly revised resulting in the description of a large number of new species (a.o. Van de Vijver et al. 2002, Van de Vijver & Mataloni 2008, Van de Vijver et al. 2010). An important part of these revisions focused on the typical terrestrial genera Luticola, Muelleria and Diadesmis. This is not surprising since one of the principal biomes in the Antarctic Region is formed by large, terrestrial ice-free areas, fellfields, wet soils, seepage areas and rocks. The soils of these areas form a suitable habitat for a large variety of terrestrial diatoms. Diatoms living in these habitats are welladapted to survive the sometimes severe conditions such as a continuously changing soil humidity and freeze-thaw cycles. Apart from the above-mentioned (already revised) genera, two other terrestrial genera form large populations within the Antarctic Region: Eunotia and Hantzschia. The present paper revises the taxonomy of the genus Hantzschia, based on observations made during a survey of the non-marine diatom flora of Livingston Island. Several unknown Hantzschia species were observed, that could not be assigned to any of the already described taxa. Five taxa will be described as new to science whereas three others are illustrated. The genus Hantzschia is a relatively small genus with less than fifty species known worldwide, occurring in a wide variety of habitats ranging from freshwater to terrestrial and even intertidal and marine environments (Round et al. 1990). Described in 1877 by Grunow, the genus, belonging to the family Bacillariaceae, is characterized by a typical asymmetrical valve outline with usually a more convex dorsal side and a concave ventral side, the presence of uniseriate striae composed of small rounded areolae containing hymenes, a raphe that is subtended by fibulae and a complex girdle structure (Round et al. 1990). Species within the genus are separated based on number of striae and areolae per stria, the position and shape of the fibulae, the shape of the external and internal proximal raphe endings and the shape of the valve apices. Hantzschia amphioxys (Ehrenb.) Grunow is considered to be the most common and well known species in this genus, living almost exclusively in (semi-wet) soils. The spe-

Comparative ecology and coexistence of introduced and native congeneric forest herbs: Impatiens parviflora and I. noli-tangere

Abstract: Background and aims - Impatiens parviflora DC. is an invasive species which disturbs the natural vegetation composition in many European forests where it is frequently mixed with the native I. nolitangere L. According to the literature, both species seem to share many biological attributes and have very similar ecological requirements. Extinctions have sometimes been reported for I. noli-tangere, and knowledge is lacking about the possible contribution of I. parviflora to this phenomenon. Methods - In a large forest from central Belgium, we compared soil characteristics (inferred by the Ellenberg's indices) and strategies of the species from the recipient vegetation (according to Grime's system) between areas where (1) only one of the two Impatiens is present, and (2) both Impatiens grow together. In order to refine the knowledge of their ecological behaviour, we modelled the response of both species to these soil and community properties. Results - Contrary to what is reported in the literature, we found that, in our study area, I. parviflora prefers soils of low base and N-status, it shows a preference for compacted soils, and it easily penetrates non-ruderal communities and dense groundlayers. Conclusions - These findings suggest that the autecology of I. parviflora in western and central Europe is not very well known yet and deserves further studies. Our results also highlighted major differences in the ecological requirements of both species. We suggest that the regression of I. noli-tangere observed in many regions is not due to the invasion by I. parviflora, although additional studies are necessary to untangle this question. © 2010 National Botanic Garden of Belgium and Royal Botanical Society of Belgium.

Forest herbs in the face of global change: a single-species-multiple-threats approach for Anemone nemorosa.

Abstract: Forest herbs in the face of global change: a single-species-multiple-threats approach for Anemone nemorosa

Revision of the African genus Anthonotha (Leguminosae, Caesalpinioideae).

Abstract: Background and aims - The African genus Anthonotha (Leguminosae, Caesalpinioideae) is poorly known The species are revised Methods - Normal practices of herbarium taxonomy have been applied to study all herbarium material available, mainly at BM, BR, BRLU, COI, FHO, G, K, LBV, LISC, LISU, MA, MO, P, WAG and YA Seventeen species are recognized, including three new ones: A mouandzae from Gabon and A wijmacampensis and A xanderi from Cameroon The species are almost completely confined to the Guineo-Congolian region A full taxonomic treatment with key to species is given Some important characters which are used in this key are depicted The new species are fully illustrated The fruits of all species are illustrated as well Distribution maps of all taxa are given Anthonota cladantha is neotypified For four other species (A ferruginea, A lamprophylla, A noldeae and A trunciflora), a lectotype is designated

Taxonomic descriptions and evolutionary implications of Middle Eocene pennate diatoms representing the extant generaOxyneis,ActinellaandNupela(Bacillariophyceae)

Abstract: Actinella F.W.Lewis, Oxyneis Round and Nupela Vyverman & Compère are three genera of pennate diatoms known exclusively from freshwater environments that are predominantly dilute and acidic (Round et al. 1990, Sabbe et al. 2001, Siver et al. 2007). Of the three, Oxyneis is the smallest genus and comprises only three species (Round et al. 1990, Metzeltin & Lange-Bertalot 2007), although only two have formally been described within the genus. Oxyneis is an araphid taxon, possessing one rimoportula per valve and a large number of girdle bands, each equipped with a septum (Round et al. 1990, Kingston 2003). In this regard, Oxyneis is closely related to Tabellaria Ehrenb. ex Kütz., a common araphid freshwater diatom. Actinella and Nupela both possess a raphe, although the morphology of this feature is very different, yielding placement of the two genera into separate subclasses (Round et al. 1990). Actinella is characterized by reduced raphe slits, one rimoportula per valve, and frustules that are asymmetric along all three axes. Nupela has a fully formed raphe on one (heterovalvar forms) or both (isovalvar forms) valves and symmetric frustules. Although Nupela was established by Vyverman & Compère in 1991, the majority of species now contained within the genus were originally described as Navicula, a genus that has been split into numerous taxa in recent years (see Metzeltin & Lange-Bertalot 1998, 2007 and references therein). Phylogenies based on gene sequences

A combined analysis of morphological traits, chloroplast and nuclear DNA sequences within Santiria trimera (Burseraceae) suggests several species following the Biological Species Concept

Abstract: Species delimitation remains a difficult task in many groups of organisms. Even widespread and conspicuous tropical trees make no exception. Santiria trimera, an African rainforest tree, displays substantial morphological variability. While classical analysis of historical herbarium samples lead to the recognition of a single species, two morphotypes of S. trimera are regularly collected in Gabon and Equatorial Guinea, sometimes in sympatry: one form with stilt roots (SR) and another form without stilt roots (NSR). To assess whether these forms constitute distinct taxa and to understand evolutionary processes within African Santiria, we combined a morphological and a spatial analysis of both sympatric morphotypes in northern Gabon with a phylogenetic analysis of samples from West and Central Africa, including the island of Sao Tome. In Gabon, morphological traits, chloroplast DNA (cpDNA) and nuclear DNA (nuDNA) sequences congruently lead to the recognition of two well differentiated and reproductively isolated taxa corresponding to SR and NSR morphotypes. However, rare cases of the SR morphotype bearing DNA sequences typical of NSR individuals suggest that hybridization might sometimes occur. No evidence for habitat specialization of the two taxa was found. DNA sequences from Sao Tome formed monophyletic clades at both marker types and the nuDNA gene tree suggests that the Sao Tome population probably originated from Central Africa and subsequently underwent allopatric differentiation from continental populations. In Central Africa, S. trimera is composed of at least two distinct sympatric species following the Biological Species Concept and calls for further morphological and phenological studies and experimental crosses between them to specify their taxonomic status. Our results also show that classical taxonomic species delimitation may not always be congruent with the Biological Species Concept, calling for more population-based in situ morphological and molecular genetic analyses. (Resume d'auteur)

Environmental determinism versus biotic stochasticity in the appearance of plant species in salt-marsh succession

Abstract: Background and aims It is generally accepted that in terrestrial ecosystems the occurrence and abundance of plant species in late successional stages can be predicted accurately from prevailing soil conditions, whereas in early succession their presence is much more influenced by chance events (e.g. propagule availability). Late successional vegetation stages would therefore be deterministically structured, while early succession would be dominated by more stochastic features. To test this hypothesis in salt marsh conditions, we compared the effect of abiotic environmental factors on vegetation composition and probability of occurrence of individual species in two adjacent salt marshes, differing in age (i.e. successional stage). Material and methods In 2002, a new salt marsh was created on substrate devoid of plant diaspores in the nature reserve The Uzermonding (Nieuwpoort, Belgium). From 2002 onwards, primary colonization started on that sterile substrate by hydrochoric seed dispersal, induced by tidal water currents from an adjacent 5 ha relic of the old salt marsh. In 2005, three years after the start of the colonization process of the new salt marsh, vegetation and three abiotic environmental factors (soil texture, salinity and elevation) were recorded in a set of 155 releves on the new and old salt marsh. Key results In contrast to the general observation in other terrestrial ecosystems, the vegetation composition of the early successional stage of the new salt marsh appeared to be at least as much determined by the combined effect of the measured abiotic factors as that of the old salt marsh. As revealed by logistic regression the presence/absence of perennial species as well as annual species oldie young salt marsh could be well predicted by the measured abiotic variables. For the old salt marsh this also held for the perennial species, but not for the annual species. The stochastic appearance of gaps in the perennial vegetation cover appeared to be important for the establishment of annuals in the older salt marsh. Conclusion In the case of salt marsh succession, the generally accepted hypothesis of early successional stochasticity dominance versus late successional environmental determinism must be rejected.

Distribution of orbicules in Annonaceae mirrors evolutionary trend in angiosperms.

Abstract: Background and aims - Orbicules or Ubisch bodies have been recorded in many angiosperm families and although the first observations date back to 1865, their function in the anther remains enigmatic. In flowering plants a general evolutionary trend is observed from common occurrence of orbicules in early diverging lineages towards a more patchy distribution in derived clades of eudicots. Annonaceae was our family of choice for an in depth study of orbicule distribution in early diverging angiosperms since it met the following three criteria: (1) high tapetum diversity, (2) orbicule presence and absence recorded, and (3) recent phylogeny at genus level available. Key results - Our SEM data of eighteen species show that orbicules are more common in Annonaceae than previously perceived. The resulting orbicule distribution pattern on the family topology indicates a consistent absence of orbicules in the 'long branch clade' while orbicules are present in Anaxagorea, the ambavioids, and the 'short branch clade'. Presence of orbicules is the ancestral condition in the family. Morphologically, Annonaceae orbicules are small (<1 µm), spherical and smooth. Conclusions - The orbicule distribution pattern in Annonaceae reflects the general evolutionary trend in flowering plants. We hypothesize that orbicule presence can be considered as a powerful proxy for non-amoeboid tapetum characterization in Annonaceae.

Discrete free-boundary reaction-diffusion model of diatom pore occlusions

Abstract: 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 work is concerned with the smallest regular structures in diatom valves, the pore occlusions, and the processes involved in their formation.Theory and method - We developed a discrete, free-boundary, reaction-diffusion computer model to assess a new physically motivated hypothesis: pore occlusion patterns in the genus Achnanthes are simply expressions of silica diffusion and deposition within a pore covered by a membrane (silicalemma), whose deformation interacts with the growth of the pore boundary to control the silica influx.Preliminary results and discussion - Simulations generate some promising pore features such as bifurcating and curved protrusions that grow towards one another, as seen in diatom pore occlusions. But they tend to be irregular and, to date, taking into account of smoothing and regularizing effects only partially symmetrized formations. Potential future work on this point is outlined.

Ancistrocladus ileboensis (D.R.Congo), a new liana with unique alkaloids

Abstract: Background and aims - The taxonomy oi Ancistrocladus Wall. (Ancistrocladaceae) is poorly understood. Recent interest is stimulated by the occurrence of biologically active naphthylisoquinoline alkaloids. The discovery of the here reported novelty was made in the framework of an interdisciplinary research program dealing with alkaloid patterns, chromosome numbers, demography, genetic variability, pollination biology, and phylogenetic relationships. Methods - The morphological study was focussed on A. ileboensis and other related species occurring in the D.R.Congo. Key results - The novelty Ancistrocladus ileboensis Heubl, Mudogo & G.Bringmann is described from the Congolian lowland forests ecoregion in the south of the Congo Basin. A distribution map and illustrations are provided. The new species is compared with four closely related taxa, from which it is distinct morphologically, chemically and biogeographically: A. letestui Pellegrin, A. ealaensis J.Leonard, A. likoko J.Leonard, and A. congolensis J.Leonard. Tables showing morphological and chemotaxonomic differences of the related taxa are presented. Conclusion - The phytochemical peculiarities together with morphological features support the separation of A. ileboensis as a new species.

Observations on the limnology and phytoplankton community of crater Lake Kyaninga (Uganda), with special attention to its diatom flora

Abstract: Background and aims - With a depth of at least 220 in, Lake Kyaninga is the deepest known maar crater lake in western Uganda. We studied its limnology and phytoplankton community to determine how the frequency and depth of water-column mixing influences nutrient cycling and seasonality in this aquatic ecosystem. Methods - Water-column temperature was measured continuously during a full annual cycle between August 2007 and August 2008. Other physical and chemical variables as well as diatom and other phytoplankton communities were investigated on three occasions, namely during the dry season in August of 2007 and 2008, and during the main wet season in April 2009. Key results and conclusions - The water column of Lake Kyaninga is permanently stratified (meromictic) below similar to 100 m depth. Above this depth, mixing frequency varies from daily (down to 8-12 m depth) over at least once per year (down to 39-47 m depth), to once in several years or decades (between 39-47 and similar to 100 m depth). Nutrient and chlorophyll concentrations as well as phytoplankton data classify the lake as low in aquatic productivity (oligotrophic). Its pelagic, open-water phytoplankton community is dominated by Cyanobacteria (blue-green algae) and Chlorophyta (green algae). Bacillariophyta (diatoms) contribute only a minor part of total phytoplankton biomass in both wet and dry seasons, and are characterized by an assemblage of small Nitzschia species. Epiphytic and epipelie diatoms are relatively few, because steep rocky crater slopes limit the littoral zone even though water-column transparency is high. The composition of recently deposited diatom assemblages preserved in offshore surface sediments gives a good, annually integrated representation of the present-day pelagic diatom community. The documented species richness of the diatom flora of Lake Kyaninga is moderate with about 150 taxa. Only similar to 17% of these are biogeographically restricted to tropical Africa; and most of these belong to the genus Nitzschia.

Meiotic chromosome number and behaviour of Onobrychis avajensis (Fabaceae): a new species from western Iran.

Abstract: consistent with the proposed base number of = 8. The general meiotic behaviour of the species was regular, with bivalent pairing and normal chromosome segregation at meiosis. Meiotic abnormalities were observed included a varying degree of sticky chromosomes with laggards, precocious division of centromeres in metaphase I, bridges in anaphase I and multipolar cells in telophase II. Conclusion - Morphological features support the separation of Onobrychis avajensis Ranjbar as a new species.

Spermacoce spiralis, a new name for Diodia assurgens (Rubiaceae).

Abstract: Background and aims The identity of Diodia assurgens K.Schum. is unclear and the taxon has never been studied in detail since its description. In the present paper we aim to clarify its status and taxonomic position. Methods Normal practices of herbarium taxonomy have been applied to study all herbarium material available. Pollen oi Diodia assurgens dina Diodia s. str. species was studied using the acetolysis method. Key results The comparative morphological study clearly shows that Diodia assurgens K.Schum belongs to the genus Spermacoce s. str. and that it should be excluded from Diodia s. str. The new name Spermacoce spiralis Bacigalupo & E.L.Cabral is proposed and a lectotype is designated. The species is also described and illustrated. The palynological characters of Spermacoce spiralis agree well with those observed in other species oi Spermacoce s. str.

Checklist of Bauhinia sensu stricto (Caesalpiniaceae) in Brazil

Abstract: Background and aims - A checklist and key of the Brazilian species of the genus Bauhinia L. are presented. The species examined all have an arboreal or shrub habit or are occasionally vines or decumbent shrubs, although never with tendrils. Methods - Information was gathered and collated from an already prepared list of nomenclatural types, the examination of approximately 2,100 specimens stored in approximately 100 herbaria, and by consultation of literature about the genus. Key results - All taxonomic categories including section, series, species, subspecies, and variety, as well as the principal synonyms are included. In addition, references to illustrations in the most recent revisions are included. Accompanying information includes data recorded on the collection labels of herbarium specimens such as state, municipality, month and year of collection, reproductive stage of the specimens (floral bud, flower, or fruit), collector's name and number, and the herbaria where the specimens (including duplicates) are deposited. The list contains 57 species, two subspecies, and seven varieties of the genus Bauhinia native to Brazil. Bauhinia pinheroi is illustrated here for the first time.

Morphology of Actinocyclus and Lobodiscus species (Bacillariophyta) from the Miocene deposits of the Vitim Plateau, Russia

Abstract: Background and aims – In 2006, during a field expedition in the Amalat (Southern) paleovalley of the Vitim Plateau, 85 samples were taken from sediments of a new key hole 7236. The composition and distribution of siliceous microfossils were studied with light microscope (Usoltseva et al. 2008). The prevailence of species of the planktonic genera of Actinocyclus Ehr. and Aulacoseira Thw. was recorded. The aims of this paper were electron-microscopic investigations of fossil freshwater species Actinocyclus and Lobodiscus from the Miocene lacustrine sediments of a new key hole 7236, and the comparison of our morphological data with formerly published descriptions of known freshwater taxa of these genera. Methods – Samples from the section 7236 were examined using LM and SEM. Abundance was calculated based on the LM slides. Key results – Valve ultrastructure of dominant biostratigraphically valuable species of Actinocyclus and Lobodiscus from the Miocene freshwater sediments of the Vitim Plateau was for the first time studied with SEM. The comparison of results of carried out investigations with formerly published descriptions of known freshwater taxa of Actinocyclus and Lobodiscus permits to belong the studied species to Actinocyclus gorbunovii (Sheshukova) Moisseeva & Sheshukova and A. krasskei (Krasske) Bradbury & Krebs, to expand their certain morphometric data, as well as to describe A. vitimicus Usoltseva & Khursevich sp. nov., A. intermedius Usoltseva & Khursevich sp. nov. and Lobodiscus peculiaris Usoltseva & Khursevich sp. nov., with definite diagnostic features. Cоnclusion – Freshwater extinct species of Actinocyclus can be used as stratigraphic markers. Thus, occurred planktonic taxa of Actinocyclus, including the new species of A. vitimicus and A. intermedius, described above, as well as Lobodiscus peculiaris together with dominant accompanying planktonic representatives of Aulacoseira represent the characteristic diatom complex in lacustrine sediments of the Upper Dzhilinda subformation recovered from key hole 7236 within the Amalat paleovalley (the Vitim Plateau). The Middle-Late Miocene age of studied lacustrine deposits agrees with K-Ar dating of lavas in this part of section.

Les indicateurs de la dynamique post-culturale de la végétation des jachères dans la partie savane de la réserve naturelle forestière de Kigwena (Burundi)

Abstract: Background and aims - A synchronic study has been achieved in fallows distributed in three age classes (0-2 years, 3-5 years and more than five years) in the natural forest reserve of Kigwena (Burundi). The aim was to show that differences in the proportion of plant functional groups could be used as indicators in characterizing the post-cultivation succession stages. Methods - The retained functional groups concerned biological and phytogeographic types, leaf size and diaspores dispersion. Key results - The data analysis gave five floristic associations. The functional group analysis evidences that the young successional stages are often characterized by sclerochorous herbaceous (therophyts) with often anemochorous dispersion, while the aged stages are essentially dominated by sarcochorous phanerophyts with essentially autochorous dispersion. The proportion of species with large distribution decreases with the age of the fallow contrary to species with regional distribution. A progressive increase with the age of species number with large leaves and a reduction of species with small leaves has been observed. Conclusion - The follow-up of the temporal variability of biological traits of species permits to characterize stages of post-cultivation succession. © 2010 National Botanic Garden of Belgium and Royal Botanical Society of Belgium.

Inheritance of the chloroplast genome in Rhinanthus angustifolius (Orobanchaceae)

Abstract: Background and aims - The mode of inheritance of the chloroplast genome is an important factor in studies dealing with population and evolutionary plant biology. In this paper, we aim to determine the chloroplast DNA (cpDNA) inheritance in Rhinanthus angustifolius. Methods - We studied the cpDNA inheritance using PCR-RFLP. One hundred sixty six offspring obtained from controlled crosses between individuals with two distinct chlorotypes were analysed. Key results - All the progeny exhibited the maternal chloroplast genome. The power analysis of the binomial distribution showed that the frequency of paternal transmission of the chloroplast, if any, should not exceed 1.81% (with 95% confidence). This work indicates that maternal inheritance of the chloroplast genome in Rhinanthus angustifolius is a reasonable assumption.

Description of a new species of Neuropeltis (convolvulaceae) with a synopsis and a key to all African species.

Abstract: Background and aims - The paleotropical genus Neuropeltis of the Convolvulaceae is imperfectly known The present paper aims to revise the genus for the Upper Guinea area in West Africa Methods - Normal practices of herbarium taxonomy have been applied to study all herbarium material available Key results - Three species are found in Upper Guinea Neuropeltis velutina is not present in this area and its specimens hitherto assigned to it are classified in a new species N occidentalis A key to and a synopsis of all African species is provided The new species is illustrated and its distribution is mapped Neuropeltis sanguinea from Angola (Cabinda) is newly synonymised under N velutina

Some factors determining species diversity of prepuna and puna vegetations in a Bolivian Andes region

Abstract: Background and aims - The only semi-arid plant formations that occur in Andean Bolivia are prepuna with its associated dry valleys and puna. A quantitative ecological study was conducted in the district of Apillapampa, which is situated on the transition between the latter vegetation types. Methods - Vegetation was sampled in twenty-nine 50 x 2 m(2) transects, yielding a total of 280 different plant taxa. Key results - Floristic and ecological findings correspond well with comparable studies in prepuna and puna vegetations in Bolivia and significantly contribute to the still severely understudied Bolivian flora. Our research suggests that a significant part of the variation in species abundances in the sampled transects is explained by a combination of some of the natural and anthropogenic variables we measured. The latter include altitude, travel time (as a measure of site accessibility), proximity to a (temporal) river or stream, and evidence of firewood harvesting. Furthermore, we detected an inverse relationship between diversity of plants in transects and altitude. Of the anthropogenic disturbance variables, only cultivation of exotic tree or shrub species had a negative impact on plant diversity in transects. Conclusions - Vegetation in Apillapampa is highly fragmented and of secondary nature, mainly as a consequence of past and present human activities.

Seed germination tests of the parasitic perennial Viscum album (Viscaceae) from fragmented habitats at the northern edge of its range

Abstract: Background and aims - Despite being a rather common species throughout Europe, little is known about the effects of habitat change on the fitness of Viscum album. We expected to find a reduction in fitness in V. album populations growing in fragmented habitats resulting from a loss of genetic diversity through increased inbreeding. Methods - We studied seed germination as a measure of fitness among sixteen Belgian V. album popula tions varying in size and degree of isolation to investigate the fitness consequences of habitat fragmenta tion. Populations were sampled from two landscapes differing in their degree of habitat fragmentation and V. album population characteristics. We also compared germination percentages of three populations at three different temperatures (5, 20, 30?C) to examine the potential effects of climate change on V. album regeneration in northern Europe. Key results - Germination percentages (at 20?C) were high (69-100%) and we found no evidence of relationships between germination and population size, density, or area. There was no direct relationship between germination percentage and population isolation within study regions, but connectivity among populations appears to be important. Samples from the more fragmented habitat showed a negative correla tion between germination percentage and the proportion of females, suggesting reduced mate availability and pollination resulting from increased isolation of populations. There was no significant difference in mean germination percentages among the three temperature treatments, bui the high temperature samples (30?C) exhibited the highest variation in germination success. Conclusion - Our results suggest that V. album has evolved high germination success to compensate for limited success in establishing on a host plant. Successful germination under a wide range of environmental conditions is expected to increase the likelihood of establishing on host plants, possibly helping V. album respond to changes in climate.