Systematic study ofOsbertia (Asteraceae-Astereae)

Osbertia, a stoloniferous group confined to the montane regions of Mexico and adjacent Guatemala, was first proposed as a genus byGreene (1895), but most workers have retained the taxon as part ofHaplopappus. It is clearly closer toNoticastrum, Erigeron orHeterotheca than it is toHaplopappus sensu stricto. The present treatment recognizes two species, a widespread highly variableOsbertia stolonifera and a newly describedO. chihuahuana from northwestern Mexico. Distribution maps, distinguishing features, full synonymy and illustrations are presented.     

Heterostyly in species ofNarcissus (Amaryllidaceae) andHugonia (Linaceae) and other disputed cases

The hypothesis ofHenriques andFernandes that several Iberian species ofNarcissus (Amaryllidaceae) are tristylous is reconsidered. Contrary to the opinion ofBateman and most subsequent authors, we believe that the available evidence indicates that some populations ofN. triandrus andN. fernandesii, at least, are tristylous; other populations ofN. triandrus are distylous.Hugonia cf.penicillanthemum (Linaceae) from new Caledonia is distylous, but it remains possible that other species ofHugonia are tristylous. The disputed occurrence of heterostyly in S. African species ofBauhinia (Leguminosae),Cleome (Capparaceae) andAneilema (Commelinaceae), and inAgelaea (Connaraceae) is discussed.     

ThechlL (frxC) gene: Phylogenetic distribution in vascular plants and DNA sequence fromPolystichum acrostichoides (Pteridophyta) andSynechococcus sp. 7002 (Cyanobacteria)

We examinedchlL (frxC) gene evolution using several approaches. Sequences from the chloroplast genome of the fernPolystichum acrostichoides and from the cyanobacteriumSynechococcus sp. 7002 were determined and found to be highly conserved. A complete physical map of the fern chloroplast genome and partial maps of other vascular plant taxa show thatchlL is located primarily in the small single copy region as inMarchantia polymorpha. A survey of a wide variety of non-angiospermous vascular plant DNAs shows thatchlL is widely distributed but has been lost in the pteridophytePsilotum and (presumably independently) within the Gnetalean gymnosperms.The namefrxC was originally used to denote a gene encoding a product with probable Fe : S cluster binding activity. This activity was postulated due to the amino acid sequence similarity between this product and the Fe : S-binding nitrogenase iron proteinnifH. Fe : S-binding is a property shared by ferredoxins, which are denoted by the prefix frx. However, this gene does not encode a ferredoxin. It is much larger than any known ferredoxin, it binds its Fe : S cluster between two halves of a homodimer (Fujita & al. 1989,Burke & al. 1993 a, c) instead of within a single subunit, and it lacks the pattern of clustered cysteines present in all ferredoxins (Meyer 1988). Therefore, we use the namechlL to recognize the sequence and functional similarities to the bacterial PChlide reductase subunit,bchL. Similar usage has been adopted for this (Suzuki & Bauer 1992) and other (Choquet & al. 1992,Burke & al. 1993b) PChlide reductase subunits.     

Generic delimitation of Aralia (Araliaceae)

Aralia, described by Linnaeus, remains a poorly defined genus. Many satellite genera ofAralia have been proposed, and some have been accepted without critical evaluation. These genera includeCoudenbergia, Megalopanax, Parapentapanax, andPentapanax. This study examined the historical background of the establishment of these genera and their diagnostic characters. It was found that (1)Aralia s. str. is a relatively diverse genus; (2) the separation ofPentapanax andParapentapanax fromAralia is unsubstantiated; (3)Megalopanax is synonymous withCoudenbergia; and (4) the boundaries betweenAralia and bothCoudenbergia andPentapanax intergrade. It is proposed, therefore, to mergeCoudenbergia, Parapentapanax, andPentapanax withAralia, which has nomenclatural priority.Aralia is herein defined as consisting of those species in Araliaceae with pinnate leaves, articulated rachises, five to eight-merous flowers, petals imbricate in buds, and articulated pedicels. The revised generic concept requires the following new combinations or new names:Aralia castanopsisicola, A. franchetti, A. gigantea, A. laevis, A. leschenaultii, A. parasitica, A. rex, A. subcordata, A. verticillata, andA. warmingiana.     

Pollen-ovule patterns in tribeTrifolieae (Leguminosae)

Relative pollen and ovule production in the genera of the legume tribeTrifolieae is explored particularly as to howMedicago with its explosive pollination mechanism compares with its allies.Medicago produces much larger, although much fewer pollen per ovule than the other five genera in the tribe; this is interpreted as a consequence of its highly specialized, irreversible pollination mechanism, which allows only one effective exchange of pollen with pollinators.Melilotus andTrifolium produce a comparatively large quantity of pollen; this can be related to their floral characteristics requiring abundant pollen to achieve fertilization. InMedicago andTrigonella, annuals convert a higher proportion of pollen grains and ovules into seeds than perennials.     

Development of Encarsia bimaculata (Heraty and Polaszek) (Hymenoptera: Aphelinidae) in Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) nymphs

Encarsia bimaculata was recently described from India as a potentially useful parasitoid of Bemisia tabaci. Its developmental biology was studied in the laboratory at 25–30 °C and 70–75% RH. Results showed that E. bimaculata is a solitary, arrhenotokous, heteronomous, autoparasitoid. Mated females laid eggs internally in B. tabaci nymphs that developed as primary parasitoids. Males developed as hyperparasitoids, either in females of their own species or in other primary aphelinid parasitoids. Superparasitism was common under cage conditions. Both sexes have an egg, three larval instars, prepupal, and pupal stages. Development from egg to adult took 12.70 ± 2.10 days for females and 14.48 ± 2.60 days for males. Individual B. tabaci nymphs were examined for E. bimaculata parasitization using three isozymes: esterase, malate dehydrogenase, and xanthine dehydrogenase. All three isozymes showed differential banding patterns that identified E. bimaculata parasitized or unparasitized B. tabaci nymphs.     

Floral development in Adonideae (Ranunculaceae)

Floral development and floral phyllotaxis in species of Adonis, Callianthemum, and Trollius (Ranunculaceae) were studied with scanning electron microscopy. The floral organs are initiated in spiral sequence and the flowers have spiral phyllotaxis. The sepal primordia are broad, crescent-shaped, and truncate, but those of petals, stamens, and carpels are rather hemispherical. A relatively long plastochron appears to be present between the last sepal and the first petal as compared with the short and equal plastochrones of all subsequent floral organs. Maturation of the stamens within the androecium appears to be centripetal. The carpels have a short ascidiate zone. Placentation is uniformly lateral, even in Adonis and Callianthemum, which have only one fertile ovule per carpel (versus median in other genera of Ranunculoideae with a single fertile ovule). In Adonis and Callianthemum at the tip of the carpel the ventral slit is gaping and the stigma is broadly exposed, whereas in Trollius the stigma is narrower and more pronouncedly decurrent along the ventral slit. The petals in Callianthemum and Trollius are more conspicuously delayed in development than those in Adonis as compared with sepals and stamens. A short carpel stipe is formed early in Callianthemum but later in Adonis and Trollius. In Trollius farreri (commonly having only five carpels in contrast to other species of Trollius) the carpels form a single (spiral) series. Thus floral development is similar in all three genera and, at a lower level, Adonis and Callianthemum are especially close but have different autapomorphies, which reflects the current classification of the genera.     

Sero-systematics ofCytisus sect.Trianthocytisus (Fabaceae)

The serological reaction of seed proteins provides evidence for a partly new systematic arrangement ofCytisus sect.Trianthocytisus and ofCytisus s.l. Proposed modifications agree with recent advances in morphological taxonomy. Sect.Trianthocytisus includes only two species,C. villosus andC. aeolicus. Its position is central within the genus, and this fact agrees with the proposed retypification ofCytisus (type species:C. villosus).C. emeriflorus, formerly included in the same section, constitutes the monospecific sect.Emeroides, which is intermediate towards the genusLembotropis. This is serologically isolated and includes onlyL. nigricans. It is confirmed thatC. sessilifolius should be removed from the genusCytisus as a monospecific genus:Cytisophyllum Lang which is closely allied toHesperolaburnum and toPodocytisus, the most primitive genera ofGenisteae.     

A functional interpretation ofLactuceae (Compositae) pollen

Pollen morphology and ultrastructure inLactuceae pollen is considered in relation to the accomodation of volume changes, pollination biology and exine-held substances. Echinate pollen grains, such as those ofCatananche, are shown to accomodate volume changes by folding along the colpi and possibly by volume changes in the cavea. The different patterns of echinolophate pollen respond in different ways. Folding along the colpi is important inScorzonera andTragopogon and to a limited extent inCichorium andEpilasia whilst inScolymus the colpi are almost immobilized. Movements of the lacunar floors take over the harmomegathic function to compensate for lack of colpus mobility. Bulging of the intine at the apertures and changes in the size of the cavea may account for part of the volume change accomodated in any pollen type. Echinolophate pollen is interpreted as being a superior means of regulating volume changes with the most economical and mechanically efficient use of wall material which has evolved independently in several tribes ofCompositae.     

Chemosystematics ofSuillaceae andGomphidiaceae (suborderSuillineae)

The chemotaxonomic findings relating to the generaBoletinus, Suillus, Gastroboletus, Gomphidius, andChroogomphus are summarized and discussed, using published data as well as our own hitherto unpublished evidence of pigments and chromogens. The study confirms repeatedly made claims that these genera are closely related. In addition to the presence of pigments which are typical for most members of theBoletales (e.g., pulvinic acid derivatives, terphenyl quinones, cyclopentenones), prenylated phenols and quinones can also be constantly detected here (with the exception ofBoletinus), just as inRhizopogon. Accordingly,Suillus is more closely related to theGomphidiaceae andRhizopogonaceae than to the remaining boletes. It is therefore necessary to establish a new family (Suillaceae which includeBoletinus, Suillus, andGastrosuillus) and a new suborder (Suillineae which includeSuillaceae, Gomphidiaceae, andRhizopogonaceae) within theBoletales. Chemosystematics ofBoletales 2. For part 1 seeBesl & al. (1986). Dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer on the occasion of his 70th birthday     

Revision ofDoniophyton (Compositae, Barnadesioideae)

This revision describes, illustrates and documents morphological variation inDoniophyton (Compositae, Barnadesioideae), restricted to Argentina and Chile. Two species are recognized,D. anomalum andD. weddellii (sp. nova), possessing distinct morphological and chromosomal features, elevational tolerances, and nearly allopatric distributions.Doniophyton weddellii occurs primarily in central to northern Andean Chile and Argentina from 1900–4000 m a. s. l.;D. anomalum is found principally in centralwestern Argentina and south into Patagonia at 0–1800 m a. s. l. Close relationship exists withChuquiraga of subfam.Barnadesioideae. It is hypothesized thatDoniophyton evolved out ofChuquiraga in the high central Andes between Chile and Argentina. It is suggested thatD. weddellii differentiated first, correlating with an aneuploid chromosomal decrease from n = 27 (inChuquiraga) to n = 25. Further evolution and chromosomal decrease to n = 24 resulted inD. anomalum, with accompanying migration into southern Andes and Patagonia. Nomenclatural changes result from examination of protologues and type specimens:Doniophyton anomalum replaces the commonly used nameD. patagonicum, and a new species,D. weddellii, is described for the taxon masquerading under the routinely used superfluous nameD. andicola. This paper is dedicated with admiration and respect to emer. Univ.-Prof. DrFriedrich Ehrendorfer, one of the world's outstanding plant systematists, and a leading scientist and administrator of the Institute of Botany of the University of Vienna     

Recognition of heterospecific parasitism: Competition between Aphidiid (Aphidius ervi) and Aphelinid (Aphelinus asychis) parasitoids of Aphids (Hymenoptera: Aphidiidae; Aphelinidae)

The solitary parasitoids Aphidius erviHaliday (Hymenoptera: Aphidiidae) and Aphelinus asychisWalker (Hymenoptera: Aphelinidae) attacked but generally did not oviposit in pea aphids parasitized by the other species. Wasps selectively oviposited in unparasitized hosts when given a choice. Host discrimination depended on the recognition of internal cues. Females of A. asychiseither could not recognize or ignored A. ervi'sexternal host marking pheromone. Under most conditions, A. ervisurvived in superparasitized hosts, killing competing A. asychislarvae by physical attack and possibly physiological suppression. The outcome of larval competition was not affected by oviposition sequence or age difference between larvae; A. asychissurvived only when it had substantially completed larval development before the host was superparasitized by A. ervi.It is suggested that competition for host resources incurs a cost, for the winner in terms of reduced size or increased development time and for the loser in terms of lost progeny and searching time. Consequently, heterospecific host discrimination can be functional. Internal, and probably general, cues enable wasps to recognize and avoid oviposition in hosts already parasitized by an unrelated species.     

A cysteine endopeptidase from tick (Rhipicephalus (Boophilus) microplus) larvae with vitellin digestion activity

The hard tick Rhipicephalus (Boophilus) microplus is a blood-sucking ectoparasite. R. microplus free-living stage comprises egg development, hatching, and subsequent larval development until encountering a host. In order to complete the embryological development, this tick relies on yolk reserve substances, mainly vitellin (Vt), which is still present in the larval stage. The present study demonstrates presence and digestion of Vt in unfed R. microplus larvae. An increasing proteolytic activity is observed in larval development, as well as a decrease in total protein and in Vt content. Partial purification and characterization of a R. microplus larval cysteine endopeptidase (RmLCE) with Vt-degrading activity is also described. RmLCE has optimal activity at 37 °C at pH 5.0, being unstable at pH ≥ 7.5. This enzyme is active upon fluorogenic peptide substrates and is able to degrade Vt, its putative natural substrate. These results indicate that RmLCE has a role in supporting the nutritional needs of unfed R. microplus larva through Vt proteolysis, allowing survival until the first blood meal.     

Some Entolomataceae (Agaricales) from Costa Rica

A preliminary account of Entolomataceae from Costa Rica is presented. Three new taxa are described, two inClitopilus, one inRhodocybe, and three new combinations are proposed inInocephalus. Five taxa ofClitopilus are reported for the first time from Costa Rica and a key to species is provided. Four species ofRhodocybe are discussed and a key to the six species known from Costa Rica is also provided.Alboleptonia earlei, Inocephalus murraii, Inocephalus quadratum, Rhodocybe incarnata andRhodocybe pseudonitellina are now known to occur in Costa Rica.     

Phylogenetic Framework for Trema (Celtidaceae)

We used ITS and trnL sequence data, analyzed separately and combined by MP, to explore species relationships and concepts in Trema (Celtidaceae), a pantropical genus of pioneer trees. Whether Trema is monophyletic or includes Parasponia is still unresolved. Three clades within Trema received moderate to high support, one from the New World and two from the Old World, but their relationships were not resolved. In the New World, specimens of T. micrantha formed two groups consistent with endocarp morphology. Group I, with smaller brown endocarps, is a highly supported clade sister to T. lamarckiana. Group II, with larger black endocarps, is poorly resolved with several subclades, including the highly supported T. integerrima clade. Both Old World clades contain Asian and African species, with three or more species in each region. Trema orientalis is not monophyletic: specimens from Africa formed a highly supported clade sister to T. africana, while those from Asia were sister to T. aspera from Australia.     

Chrysosphaerella (Pseudochrysosphaerella)solitaria,spec. nova (Chrysophyceae)

A new unicellular species of the genusChrysosphaerella (Chrysophyceae) was found in fresh-water ponds in Switzerland, Japan, and the U.S.A. It is described asC. solitaria. The genus is divided into two subgenera:Chrysosphaerella, comprising the colonial species, andPseudochrysosphaerella, the unicellular ones.     

Origin and taxonomic affinities of Thelypteris (subgen. Stegnogramma) burksiorum (Thelypteridaceae)

This paper examines the ecology, frond and spore morphology, gametophytes, and molecular biology ofThelypteris burksiorum to reveal its taxonomic affinities and phytogeographic origin. The species is endemic to Winston County in northern Alabama (U.S.A.) and only occurs in cave-like rockhouse habitats. A related species,T. pilosa, is widespread in central and southern Mexico, Guatemala, and Honduras.Thelypteris pilosa is extremely variable and our data suggest that current recognition of the varietiesmajor andpilosa is not warranted.Thelypteris pilosa is clearly closely related and likely sister toT. burksiorum. Thelypteris burksiorum exhibits the unusual production of gametophytic propagules. This, in combination with current levels of genetic diversity and reproductive biology, suggests thatT. burksiorum is an ancient Tertiary relict and not an example of recent long distance dispersal. Selection in rockhouse habitats has driven species away from their normal life cycle to partial or complete reliance on the gametophyte generation. The combination of a reduced yet fertile sporophyte and a gametophyte that may rely on gametophytic proliferation placesT. burksiorum in an intermediate evolutionary position relative to other rockhouse pteridophytes.     

Isolation ofNosema slovaca (Microsporidiae) fromDermacentor reticulatus ticks (Acari: Ixodidae) collected in Hungary

Nosema slovaca (Microsporidiae) was isolated from a maleDermacentor reticulatus tick collected in the Mélykút locality, Bács-Kiskun province, Hungary. This parasitic protozoan caused an acute infection in partly engorgedD. reticulatus females when inoculated intracoelomically resulting in death of the ticks within 5–15 days post-infection. This strain ofNosema can be maintained in the laboratory by passaging between partly engorgedD. reticulatus females and is currently being studied for its potential as a biological control agent of ixodid ticks.     

Dioecy inMikania (Compositae:Eupatorieae)

For the first time dioecy inMikania and in the tribeEupatorieae is described and discussed. The condition is known only in members of theMikania swartziana Griseb. complex, a group of eight species, all endemic to the Greater Antillean Islands of Cuba, Hispaniola, and Jamaica.     

Field observations in the Oosterschelde (The Netherlands) onCoscinodiscus concinnus andCoscinodiscus granii (Bacillariophyceae) infected by the marine fungusLagenisma coscinodisci (Oomycetes)

During 1985–1990Coscinodiscus concinnus andCoscinodiscus granii from the Oosterschelde were infected by the marine fungusLagenisma coscinodisci, although not every year with the same intensity. Infected cells were only observed during the period July–October at water temperatures between 13.2 and 20.2°C. In 1986 and 1987 the course of the infection withL. coscinodisci inC. concinnus andC. granii, was recorded at three stations. The highest infection percentages varied between 22.2 and 58.3% inC. concinnus and between 7.1 and 41.9% inC. granii. It is concluded that the water temperature may play an important role in the appearance ofL. coscinodisci inC. concinnus andC. granii and that silicate limitation is of minor importance. Finally it is discussed that the infection was not of great importance for the phytoplankton community in the Oosterschelde.