Persistent nuclear ribosomal DNA sequence polymorphism in the Amelanchier agamic complex (Rosaceae)

Individual plants of several Amelanchier taxa contain many polymorphic nucleotide sites in the internal transcribed spacers (ITS) of nuclear ribosomal DNA (nrDNA). This polymorphism is unusual because it is not recent in origin and thus has resisted homogenization by concerted evolution. Amelanchier ITS sequence polymorphism is hypothesized to be the result of gene flow between two major North American clades resolved by phylogenetic analysis of ITS sequences. Western North American species plus A. humilis and A. sanguinea of eastern North America form one clade (A), and the remaining eastern North American Amelanchier make up clade B. Five eastern North American taxa are polymorphic at many of the nucleotide sites where clades A and B have diverged and are thought to be of hybrid origin, with A. humilis or A. sanguinea as one parent and various members of clade B as the other parent. Morphological evidence suggests that A. humilis is one of the parents of one of the polymorphic taxa, a microspecies that we refer to informally as A. "erecta." Sequences of 21 cloned copies of the ITS1- 5.8S gene-ITS2 region from one A. "erecta" individual are identical to A. humilis sequence or to the clade B consensus sequence, or they are apparent recombinants of A. humilis and clade B ITS repeats. Amelanchier "erecta" and another polymorphic taxon are suspected to be relatively old because both grow several hundred kilometers beyond the range of one of their parents. ITS sequence polymorphisms have apparently persisted in these two taxa perhaps because of polyploidy and/or agamospermy (asexual seed production), which are prevalent in the genus.      

Morphology and microhabitat preferences of benthic foraminifera from the northwest Atlantic Ocean

The distribution of Rose Bengal stained calcareous benthic foraminifera was determined in six ☐ cores raised from water depths between 200 and 3000 m on the Nova Scotian continental margin and Gulf of Maine. The taxa can be separated into four microhabitats within the surficial sediments. Epifaunal taxa are generally found in the top cm, intermediate infaunal taxa are found from about 1 to 4 cm and deep infaunal taxa are found at > 4 cm sediment depth in at least one ☐ core. A fourth group, shallow infaunal taxa, is found in the top 2 cm and is inferred to be infaunal based on wall porosity characteristics and test shapes similar to infaunal taxa. The epifaunal, shallow infaunal and intermediate infaunal taxa maintain their positions within the sediments from core to core, whereas the deep infaunal taxa are found at progressively shallower sediment depths in cores within increasing organic carbon contents from shallower water depths.Each microhabitat category has distinct morphological characteristics. Epifaunal taxa have plano-covex or biconvex cross sections, trochospiral coiling and large pores absent or found on only one side. Shallow infaunal taxa have uniserial, triserial, or planispiral coiling, with surface ornamentation present on a number of taxa. The intermediate infaunal taxa have rounded peripheries, pores over the entire test and planispiral coiling, with the exception ofCibicidoides bradyi which has trochospiral coiling. The deep infaunal taxa have, in general, planispiral or triserial coiling with cylindrical or ovate shaped tests.     

The Commelinaceae of West Africa: A biosystematic survey

All the known West African taxa are surveyed and their variation and distribution is discussed. Chromosome numbers for most of the taxa are given, in many cases for the first time, and published cytological data for those genera occurring in West Africa is reviewed. Many of the taxa have been studied under cultivation and most under living conditions in the field. The results of these observations are considered in relation to the evolution of new variations and to the taxonomy of the groups concerned. The following new taxa are described: Aneilema beniniense subsp. leonense, C'ommelina diffusa subsp. montana, Floscopa africana subsp. petrophila and Slanfieldiella axillaris. Several nomenclatural changes have been made, the most important being the recognition that the African species Commelina gerrardi C. B. Clarke and C. vogelii C. B. Clarke are conspecific with the American C. erecta Linn, which thus becomes a pantropie species complex. Several species are recorded from West Africa for the first time including: Coleolrype kiurentii K. Schum. Commelina carsonii C. B. Clarke, C. zambesiaca C. B. Clarke, Cyanotis arachnoidea C. B. Clarke, and Palisota lagopus Mildbr. The pattern of variation in the larger species complexes in the genera Aneilema, Commelina, Cyanotis and Floscopa is considered in detail. These and other groups in the family are considered to be in an active state of evolutionary change. The factors which have stimulated these changes and the biological processes by means of which they are brought about are discussed. Attention is drawn to the suitability of this family for evolutionary studies and its value in the teaching of experimental taxonomy in the tropics.     

Mericarp morphology and its systematic implications for the genus Salvia L. section Hymenosphace Benth. (Lamiaceae) in Turkey

Mericarp morphology of 15 taxa of Salvia L. section Hymenosphace Benth. in Turkey were investigated by light microscopy (LM) and scanning electron microscopy (SEM) to evaluate the utility of mericarp characters in systematic studies. Mericarps ranged from 2.50 to 5.38?mm in length and 2.04 to 4.70?mm in width. Mericarp shape was prolate-spheroid or near spherical with a length-to-width ratio of 1.02?C1.48. Transverse sections of the mericarps were rounded or rounded-trigonous. Mericarp surfaces presented colliculate, reticulate, verrucate or foveate sculpturing patterns, mostly as a result of the sculpturing of the exocarp cell walls with the pattern determined by whether the periclinal walls were concave or convex and whether the anticlinal walls were raised or sunken. Colliculate surface sculpturing (periclinal walls convex) was the most common among the taxa examined. The variation in the nature of surface sculpturing, mericarp shape and size, exocarp cell shape, nature of transverse sections and abscission scar diameter proved useful diagnostic characters. Variation was sufficient to distinguish taxa at species level, including morphologically similar species. Data provided here are also relevant to phylogenetic questions at higher levels within Salvia.     

Multilocus analysis of a taxonomically densely sampled dataset reveal extensive non-monophyly in the avian family Locustellidae

The phylogeny of most of the species in the avian passerine family Locustellidae is inferred using a Bayesian species tree approach (Bayesian Estimation of Species Trees, BEST), as well as a traditional Bayesian gene tree method (MrBayes), based on a dataset comprising one mitochondrial and four nuclear loci. The trees inferred by the different methods agree fairly well in topology, although in a few cases there are marked differences. Some of these discrepancies might be due to convergence problems for BEST (despite up to 1×10(9) iterations). The phylogeny strongly disagrees with the current taxonomy at the generic level, and we propose a revised classification that recognizes four instead of seven genera. These results emphasize the well known but still often neglected problem of basing classifications on non-cladistic evaluations of morphological characters. An analysis of an extended mitochondrial dataset with multiple individuals from most species, including many subspecies, suggest that several taxa presently treated as subspecies or as monotypic species as well as a few taxa recognized as separate species are in need of further taxonomic work.     

Herbivory on a chemically defended plant as a predation deterrent in Hyalella azteca

SUMMARY 1. We investigated whether a population of the freshwater amphipod, Hyalella azteca , which consumed plants with defensive secondary compounds, reduced predation as reported for terrestrial and marine systems.
2. Field observations in Montezuma Well, U.S.A., indicated a strong association between the emergent macrophyte, Berula erecta and H . azteca . We hypothesised that this geographically isolated population of sedentary amphipods was able to consume roots of the chemically defended B . erecta as a deterrent against predation. Berula erecta is in the family Apiaceae, which commonly produce coumarins that deter herbivory in terrestrial systems.
3.  Hyalella azteca consumed roots of B . erecta at a significantly greater rate than alternative macrophyte substrata in Montezuma Well. Additionally, H . azteca moulted at a significantly higher rate when consuming B . erecta compared with a diet of periphyton.
4. Two insect predators ( Telebasis salva and Belostoma bakeri ) with different feeding strategies were used to assess the effects of a B . erecta diet on predation rates in the laboratory and in Montezuma Well. Hyalella azteca was preyed on at a significantly lower rate by both predators when given a strict diet of B . erecta roots compared with a diet of periphyton.
5. This is the first experimental evidence that predation on a freshwater herbivore, H . azteca , was reduced when it consumed a chemically defended plant.     

A numeric, geographic and structural analysis of the Hakea falcata group (Proteaceae)

Specimens placed earlier under Hakea falcata are shown to comprise four species: H. falcata, H. ulicina, H. erecta and H. cygna. Failure by previous authors to cite types, or the correct type, led to the placement of subsequently collected H. falcata specimens (sensu R. Br.) under H. ambigua in Australian herbaria. The relationships of the five taxa are explored phenetically using metric multidimensional scaling and cluster analysis. Flowers provide the best diagnostic characters for separating H. falcata and H. ambigua , while fruits and seeds are better for H. erecta and H. cygna. All species are endemic to SW Australia, except H. ulcina , which is endemic to SE Australia. Two subspecies of H. cygna are recognized, based on populations with disparate leaf morphology. Each taxon has a distinctive leaf anatomy with all but H. falcata highly sclerophyllous.     

Local and regional dominance of woody plants along an elevational gradient in a tropical montane forest of northwestern Bolivia

The aim of this study was to investigate the dominance patterns of woody plants in a tropical montane forest of northwestern Bolivia and to understand underlying processes at the local and regional scales. We inventoried three elevation ranges: lower (1,200–1,500 m), intermediate (2,000–2,300 m), and upper montane forests (2,800–3,100 m). At each elevation, we inventoried two sites that were ~100 km apart. Specifically, we asked the following questions: (1) are dominant taxa distributed locally, or are they also dominant at larger scales? And (2) is the local importance of shared taxa congruent among sites at the same elevation range? We inventoried 18,876 woody plant individuals with a diameter at breast height ≥2.5 cm belonging to 877 species, 286 genera, and 100 families in 54 0.1-ha plots. A strong floristic congruence was found at the family and genus levels within and across elevations, but not at the species level. The pattern of species dominance for the whole study regions was similar to that reported for similar scales in the Amazonia (10–15 % of species accounted for 50–75 % of individuals), although dominant species were not oligarchic across the whole elevational gradient due to the high environmental heterogeneity. Dominant taxa were shared to a larger degree between sites at the same elevational range than non-dominant taxa, indicating that oligarchy does not mean uniformity. Finally, the shared taxa exhibited similar importance between sites at the lower elevation range but dissimilar importance at the higher elevation range, reflecting an increase in the relative importance of local processes versus regional processes with increasing elevation.     

Relating macroinvertebrate community structure to environmental characteristics and sediment contamination at the scale of the St. Lawrence River

There is still no assessment of the impact of sediment chemicals and environmental conditions on macroinvertebrates at the scale of the St. Lawrence River. In order to assess these impacts in the fluvial section of the St. Lawrence River including the Montreal harbour, the community structure of macroinvertebrates using different taxonomic aggregations (genus and family) and taxa attributes (abundance, presence–absence, indicator taxa) was assessed. The goal of the study was to determine the indicator taxa of macroinvertebrates along the fluvial continuum and relate changes in macroinvertebrate community to sediment chemical conditions and environmental characteristics of habitats using variance partitioning. This study also evaluated which taxonomic level and taxa attributes of macroinvertebrates were the most suitable for bioassessment of quality of sediments and habitat environment in the St. Lawrence River. Four different macroinvertebrate assemblages were found distributed along the fluvial continuum using either abundance or presence–absence data and genus or family levels. Indicator taxa characteristic of the different macroinvertebrate communities were associated with the sediment contamination gradient. However, habitat environmental characteristics (water masses, sulphur and DOC in sediments) had more influence on macroinvertebrate assemblages than sediment contamination. Our study confirms that family level analysis can give information comparable to the genus level analysis using presence–absence or abundance of macroinvertebrates, yet a higher number of indicator taxa were detected at the genus level.     

Molecular approach for assessing responses of microbial-feeding nematodes to burning and chronic nitrogen enrichment in a native grassland

A substantial proportion of the primary productivity in grassland ecosystems is allocated belowground, sustaining an abundant and diverse community of microbes and soil invertebrates. These belowground communities drive many important ecosystem functions and are responsive to a variety of environmental changes. Nematodes, an abundant and diverse component of grassland soil communities, are particularly responsive to altered environmental conditions, such as those associated with reduced fire frequency and nitrogen enrichment, with the most consistent responses displayed by microbial-feeding nematodes. However, much of the available research characterizing nematode responses to environmental change has been carried out at the taxonomic level of family or by broad trophic categories (e.g. fungivores, bacterivores). The extent to which differential responses to environmental change occurs at the genus level or below is unclear. Therefore, the objective of this study was to use molecular methods to quantify the response of microbial-feeding nematodes, at the lowest levels of taxonomic resolution, to nitrogen enrichment and changes in fire frequency. Using sequencing and quantitative polymerase chain reaction (PCR) probes for the 18S ribosomal RNA gene and the ITS1 region, we identified 19 microbial-feeding nematode taxa across four families. When nematodes were sampled across treatments, we found that some nematode taxa within a family responded similarly to nitrogen and burning treatments, while other taxa within the same family respond quite differently. Additionally, although nematodes from different families on average responded differently to nitrogen enrichment and burning, similar responses were seen in nematode taxa that span three taxonomic families. Thus, if nematodes are to be used as indicators of environmental change, care should be taken to assess the response at the lowest taxonomic level possible.     

Economic Botany ofSphenostylis (Leguminosae)

Sphenostylis, a genus of seven species in tropical and southern Africa, includes three taxa that are used by humans. Flowers and seeds of S. schweinfurthii Harms are occasionally eaten in West Africa, and this species has potential value as a forage crop. Flowers and seeds of Sphenostylis erecta (E. G. Baker) E. G. Baker subsp. erecta are eaten in parts of Central Africa, while the roots are used medicinally and as a source of dye and fish poison. The edible tubers of S. stenocarpa (Hochst, ex A. Rich.) Harms, the African yam bean, are collected from the wild in Central and East Africa. This species is cultivated for its edible seeds in west tropical Africa and for its edible tubers in Zaire. Cultivated races of S. stenocarpa may be considered domesticated forms, since they differ from wild plants of the species in a number of morphological characteristics that are evidently the result of human selection. A list of common names for the three taxa, from throughout their ranges, is presented. Sphenostylis, un género con siete especies de las regiones sur y tropical de Africa, incluye tres taxa utilizados por humanos. Las flores y semillas deS. schweinfurthii Harms son alimento ocasional en el oeste de Africa, y la especie tiene, ademas, valor potencial como forraje. Las flores y semillas de Sphenostylis erecta (E. G. Baker) E. G. Baker subsp. erecta se comen en regiones del centro de Africa, mientras que las raíces tienen usos medicinales y son fuente de colorantes y embarbascantes. Los tubérculos comestibles de S. stenocarpa (Hochst, ex A. Rich.) Harms, la jícama Africana, se colectan de plantas silvestres en el centro y este de Africa. Esta especie se cultiva por sus semillas comestibles en el oeste de Africa tropical, y por sus tubérculos comestibles en Zaire. Las razas cultivadas deS. stenocarpa pueden ser consideradas como formas domesticadas, puesto que difieren de las plantas silvestres en muchas características morfológicas que son, evidentemente, el resultado de la selección humana. Se presenta una lista de los nombres comunes para los tres taxa a lo largo de sus rangos de distribución.     

The use of AUSRIVAS predictive models to assess the response of lotic macroinvertebrates to dams in south-east Australia

1. Sites immediately below seven dams in Victoria and 12 in southern New South Wales (NSW) were sampled for macroinvertebrates using rapid bioassessment techniques. Specimens were identified to the lowest taxonomic level. The dams had different operating and discharge regimes and thus potentially different downstream effects on this fauna.
2. The AUStralian RIVer Assessment Scheme (AUSRIVAS) predictive models for macroinvertebrate composition were applied to the families and genera observed at Victorian sites and to the families only at the NSW sites. Lists of predicted taxa, their probabilities of occurrence and ratios of observed to expected taxa (O/E scores) were obtained from these models.
3. The mean O/E score for Victoria was 0.46 at the genus level and 0.63 at the family level; for NSW the mean score at the family level was 0.62. There was no significant difference between family level scores for the two states. Thus about 40% of expected families were missing at all sites. Family level scores were highly correlated ( r =0.84–0.86, P  < 0.001) with numbers of families or species at a site.
4. There was no correlation between family O/E scores (or family and species richness) and the degree to which current discharge levels below a dam differ from the natural patterns. Thus increased hydrological deviation did not result in greater biological degradation. In addition, there was no association between these biological characteristics and whether dams released surface or bottom water.
5. All the dams seemed to cause much the same disruption to the fauna. Of the families predicted to have widespread occurrence, 9–12 were found at most sites (tolerant taxa), while a larger number (14–24) were missing (intolerant taxa). The limited recolonisation below dams may well be because of the fact that dams act as barriers to drift, the most prominent route for invertebrate colonists.     

Thalloconidia in the genus Umbilicaria

Hypothalline, hyphomycetous anamorphs - thalloconidia - from 18 taxa in the lichen genus Umbilicaria have been studied in detail with the aid of scanning and transmission electron microscopy. These asexual propagules are brown to dark brown, single-to multi-cellular (up to 2500 cells), spherical to irregular, smooth to rugged; their walls two- or three-layered. The thalloconidia are produced and seceded directly from the cortex and/or the rhizinomorphs on the lower side of the thallus. Conidiomata and conidiophores are absent. The characteristics of the thalloconidia prove to be of substantial value for taxonomical work at the specific level. The anamorphs of U. antarctica and U. esculenta are described for the first time. Thirty-five taxa from the genus Umbilicaria and 10 from the genus Lasallia were screened for the occurrence of thalloconidia with negative result.     

The evolution of the diatoms (Bacillariophyta). I. Origin of the group and assessment of the monophyly of its major divisions

The diatoms are one of the best characterised algal groups. Despite this, little is known of the evolution of the group from the earliest cell to the myriad of taxa known today. Relationships among taxa at the family or generic level have been recognised in some diatoms. However, relationships at higher taxonomic levels are poorly understood and have often been strongly influenced by the first appearances of key taxa in the fossil record. An independent assessment of relationships among the diatoms at these higher taxonomic levels has been made using rRNA sequence data to infer phylogenetic relationships. In this paper we present an analysis of 18S rRNA data from several chosen centric, araphid and raphid pennate taxa. The phylogenetic inferences from these 18S rRNA sequences are supported by evidence from the fossil record and evidence from ontogenetic data. Ribosomal RNA data indicate that both the centric and araphid pennate lineages may not be monophyletic.     

Chorioactidaceae: a new family in the Pezizales (Ascomycota) with four genera

Molecular phylogenetic and comparative morphological studies provide evidence for the recognition of a new family, Chorioactidaceae, in the Pezizales. Four genera are placed in the family: Chorioactis, Desmazierella, Neournula, and Wolfina. Based on parsimony, likelihood, and Bayesian analyses of LSU, SSU, and RPB2 sequence data, Chorioactidaceae represents a sister clade to the Sarcosomataceae, to which some of these taxa were previously referred. Morphologically these genera are similar in pigmentation, excipular construction, and asci, which mostly have terminal opercula and rounded, sometimes forked, bases without croziers. Ascospores have cyanophilic walls or cyanophilic surface ornamentation in the form of ridges or warts. So far as is known the ascospores and the cells of the paraphyses of all species are multinucleate. The six species recognized in these four genera all have limited geographical distributions in the northern hemisphere.     

Vestured pits and vestured vessel member walls in some Indian dicotyledonous woods

NAIR, M. N. B. AND MOHAN RAM, H. Y., 1989. Vestured pits and vestured vessel member walls in some Indian dicotyledonous woods. The woods of 144 taxa belonging to 38 families of angiosperms were examined for vestured pits and vestured vessel member walls using scanning electron microscopy. Vestured pits are present in 66 taxa (belonging to ten families) and vestured vessel member walls occur in only six taxa (belonging to three families). In Ehretiaceae and Euphorbiaceae vestures are present only in certain vessel members. In Wrighlia tinctoria , perforation plates containing vestures have been observed in addition to the presence of vestured pits. A classification of vestured pits based on their morphology and distribution is proposed by us. In all the types of vestured pits, vestures are present on the margin of the outer pit aperture or on the pit chamber wall. Occasionally, they are present in the pit canal, on the margin and in the vicinity of the inner pit aperture and rarely over the inner walls of the vessel members. The functions of vestured pits are not clear, although several suggestions are made. Whether or not these structures affect wood processing is not presently understood. It appears that vestured pits and vestured vessel member walls have diagnostic rather than phylogenetic value.     

The familial placement of Bryowijkia (Musci: Trachypodaceae)

The synapotypic feature of seriate leaf cell papillae positioned on cell lumina and directed over the longitudinal cross walls alliesBryowijkia with the Trachypodaceae. The Hedwigiaceae consist of four closely related genera, and excludesRhacocarpus, a genus best placed in its own family, the Rhacocarpaceae. These taxa all belong in the Leucodontineae (Isobryales) and are not related to either the Grimmiales or the Orthotrichales.     

Ant protection of the nectaried fern Polypodium plebeium in central Mexico

Nectaries on fronds of Polypodium spp. have been studied previously only in cultivated specimens. We conducted field observations in middle-elevation forests in Mexico and found five ant species associated with nectaries of Polypodium plebeium and P. lepidotrichum. To investigate whether nectaries promote protection against herbivores, we performed ant-exclusion experiments with nectary-bearing ferns (P. plebeium) and other ferns without nectaries (Polypodium plesiosorum, P. furfuraceum, and Phlebodium pseudoaureum). When ants were excluded from the developing fronds of Polypodium plebeium, damage from foliage-feeding sawfly and lepidopteran caterpillars was significantly greater than in control fronds. Ferns without nectaries did not show a difference in damage between ant-excluded and control fronds. Our results demonstrate that fern nectaries can support ant defense of the plant body as do the extrafloral nectaries of many angiosperms.