Gall morpho-type corresponds to separate species of gall-inducing thrips (Thysanoptera: Phlaeothripidae)

Kladothrips rugosus Froggatt has previously been considered a single polyphagous species that, in Australia, induces galls on several species of Acacia , with the gall structure varying both within and between hosts. On Acacia papyrocarpa , two types of gall are induced by this species, one with the surface ridged but the other with the surface smooth. Using sequence data from cytochrome oxidase subunit I (CO I ) and elongation factor-1 alpha gene fragments, we show that the thrips inducing these two gall-types are genetically distinct and comprise separate lineages. Uncorrected ' p ' distances calculated from CO I gene fragments were 0.000 and 0.006 within lineages and 0.074 and 0.078 between lineages. The between-lineage distances are comparable with distances between morphologically distinct species of other Acacia gall-thrips. Re-examination of adult thrips from the two gall types revealed consistent differences in body colour, as well as in body sculpture. Together with observations on gall founding behaviour, these data indicate that the thrips populations in the two gall types on A. papyrocarpa are reproductively isolated and should be considered as separate species. The form from smooth galls on A. papyrocarpa is therefore described as Kladothrips nicolsoni sp. nov. , although the form from ridged galls can be considered only as ' K. rugosus agg.'. These inconsistencies in the taxonomic status of the various units within the K. rugosus species complex are discussed, although most of them cannot be distinguished morphologically at present.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 555–563.     

Chlorophyll Fluorescence during Drying and Rehydration in the Mosses Rhytidiadelphus loreus (Hedw.) Warnst.,Anomodon viticulosus (Hedw.) Hook. & Tayl. and Grimmia pulvinata (Hedw.) Sm.

Chlorophyll-fluorescence parameters of three mosses, Rhytidiadelphusloreus (Hedw.) Warnst.,Anomodon viticulosus (Hedw.) Hook &Tayl. and Grimmia pulvinata (Hedw.) Sm. were measured duringdrying, and following remoistening after a period of desiccation.Most changed little with drying until the full-turgor pointwas approached, when rapid changes accompanied loss of cellwater. In R. loreus all parameters decreased together down toa water content of about 30% d.wt (RWC approx. 0.15). At lowwater contents (5–16% d.wt; RWC approx. 0.02–0.08)saturating pulses tended to suppress rather than stimulate fluorescence.In A. viticulosus F_v/F_m, q_Pand     

Mycoviruses of filamentous fungi and their relevance to plant pathology

Mycoviruses (fungal viruses) are reviewed with emphasis on plant pathogenic fungi. Based on the presence of virus-like particles and unencapsidated dsRNAs, mycoviruses are common in all major fungal groups. Over 80 mycovirus species have been officially recognized from ten virus families, but a paucity of nucleic acid sequence data makes assignment of many reported mycoviruses difficult. Although most of the particle types recognized to date are isometric, a variety of morphologies have been found and, additionally, many apparently unencapsidated dsRNAs have been reported. Until recently, most characterized mycoviruses have dsRNA genomes, but ssRNA mycoviruses now constitute about one-third of the total. Two hypotheses for the origin of mycoviruses of plant pathogens are discussed: the first that they are of unknown but ancient origin and have coevolved along with their hosts, the second that they have relatively recently moved from a fungal plant host into the fungus. Although mycoviruses are typically readily transmitted through asexual spores, transmission through sexual spores varies with the host fungus. Evidence for natural horizontal transmission has been found. Typically, mycoviruses are apparently symptomless (cryptic) but beneficial effects on the host fungus have been reported. Of more practical interest to plant pathologists are those viruses that confer a hypovirulent phenotype, and the scope for using such viruses as biocontrol agents is reviewed. New tools are being developed based on host genome studies that will help to address the intellectual challenge of understanding the fungal–virus interactions and the practical challenge of manipulating this relationship to develop novel biocontrol agents for important plant pathogens.     

Khaosokia caricoides, a new genus and species of Cyperaceae from Thailand

Khaosokia caricoides , D.A. Simpson, Chayam. & J. Parn., a newly discovered genus and species of Cyperaceae is described and illustrated. The genus is characterized by a narrowly paniculate dioecious inflorescence with 2–4 nodes, each of the nodes having a leaf-like inflorescence bract that exceeds the inflorescence. Spikelets in both sexes are linear-cylindric and each flower has seven perianth bristles. The nutlet was immature in the specimens examined. The photosynthetic pathway is C₃. Khaosokia is endemic to limestone cliffs in peninsular Thailand; its conservation status is assessed as Vulnerable (VU B1a + 2a). It has affinities to tribes Cariceae, Dulichieae and some members of Scirpeae, but the exact nature of these relationships has yet to be determined. A revised key to the genera of Cyperaceae in Thailand is presented.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 357–364.     

Natural convection from leaves at realistic Grashof numbers

Abstract. The boundary layer resistance of model leaves was measured in still air, at a range of leaf-to-air temperature differences. The results were compared to those calculated from standard formulae for natural convection. The agreement between observed and calculated was only satisfactory when Grashof numbers exceeded about 105. At the lower Grashof numbers, which often prevail in nature, the observed rates of heat transfer considerably exceeded those calculated.     

ONTOGENETIC NICHE SHIFT IN THE BRACHIOPOD TEREBRATALIA TRANSVERSA: RELATIONSHIP BETWEEN THE LOSS OF ROTATION ABILITY AND ALLOMETRIC GROWTH

Abstract: Many articulated brachiopods experience marked life habit variations during ontogeny because they experience their fluid environment at successively higher Reynolds numbers, and they can change the configuration of their inhalant and exhalant flows as body size increases. We show that the extant brachiopod Terebratalia transversa undergoes a substantial ontogenetic change in reorientation governed by rotation around the pedicle. T. transversa′s reorientation angle (maximum ability to rotate on the pedicle) decreases during ontogeny, from 180 degrees in juveniles to 10–20 degrees in individuals exceeding 5 mm, to complete cessation of rotation in individuals larger than 10 mm. Rotation ability is substantially reduced after T. transversa achieves the adult lophophore configuration and preferred orientation with respect to ambient water currents at a length of 2.5–5 mm. We hypothesize that the rotation angle of T. transversa is determined mainly by the position of ventral and dorsal points of attachment of dorsal pedicle muscles relative to the pedicle. T. transversa shows a close correlation between the ontogenetic change in reorientation angle and ontogeny of morphological traits that are related to points of attachment of dorsal pedicle muscles, although other morphological features can also limit rotation in the adult stage. The major morphological change in cardinalia shape and the observed reduction of rotation affect individuals 2.5–10 mm in length. The position of ventral insertions of dorsal pedicle muscles remains constant, but contraction of dorsal pedicle muscles is functionally handicapped because dorsal insertions shift away from the valve midline, rise above the dorsal valve floor, and become limited by a wide cardinal process early in ontogeny (<5 mm). The rate of increase of cardinal process width and of distance between dorsal pedicle muscle scars substantially decreases in the subadult stage (5–10 mm), and most of the cardinalia shell traits grow nearly isometrically in the adult stage (>10 mm). T. transversa attains smaller shell length in crevices than on exposed substrates. The proportion of small‐sized individuals and population density is lower on exposed substrates than in crevices, indicating higher juvenile mortality on substrates prone to grazing and physical disturbance. The loss of reorientation ability can be a consequence of morphological changes that strengthen substrate attachment and maximize protection against biotic or physical disturbance (1) by minimizing torques around the pedicle axis and/or (2) by shifting energy investments into attachment strength at the expense of the cost involved in reorientation.     

Trophic ecology of parabiotic ants: Do the partners have similar food niches?

Organisms associated with another species may experience both costs and benefits from their partner. One of these costs is competition, which is the more likely if the two species are ecologically similar. Parabioses are associations between two ant species that share a nest and often attend the same food sources. Albeit parabioses are probably mutualistic, parabiotic partners may compete for food. We therefore investigated feeding niches and dietary overlap of two parabiotically associated ants in Borneo using cafeteria experiments and stable isotope analyses. The two species strongly differed in their food choices. While Crematogaster modiglianii mostly foraged at carbohydrate‐rich baits, Camponotus rufifemur preferred urea‐rich sources. Both species also consumed animal protein. The ¹⁵N concentration in Ca. rufifemur workers was consistently lower than in Cr. modiglianii. Camponotus rufifemur but not Cr. modiglianii possesses microbial endosymbionts, which can metabolize urea and synthesize essential amino acids. Its lower ¹⁵N signature may result from a relatively higher intake of plant‐based or otherwise ¹⁵N‐depleted nitrogen. Isotopic signatures of the two partners in the same parabiosis showed strongly parallel variation across nests. As we did not find evidence for spatial autocorrelation, this correlation suggests an overlap of food sources between the two ant species. Based on model simulations, we estimated a diet overlap of 22–66% for nitrogen sources and 45–74% for carbon sources. The overlap may arise from either joint exploitation of the same food sources or trophallactic exchange of food. This suggests an intense trophic interaction and potential for competition between the parabiotic partners.     

Modulation of the Plasma Membrane Electron Transfer System in Root Cells of Limnobium stoloniferum by External pH

The influence of ferricyanide on transmembrane electron transfer,proton secretion, membrane potential, and cytoplasmic pH ofLimnobium stoloniferum (G.F. Mey) Griseb. root cells was investigatedat different external pH HCF III reduction by the roots was accompanied by membrane depolarization,an increase in proton secretion and by alkalinization of thecytoplasm. Change of membrane potential and cytoplasmic pH aswell as transmembrane e^– transfer was more pronouncedat acid external pH. The rate of proton flux was linearly dependenton the rate of electron transfer. The slope of the relationshipwas around 1, independent of external pH The data are in agreement with the hypothesis that electrontransfer at the plasma membrane is directly coupled to protonsecretion. It is suggested that both e^– and redox-coupledH⁺ transport are activated by acid external pH Key words: Plasmalemma redox system, electron transfer, proton transport, pH, membrane potential, Limnobium stoloniferum     

Microstructure and affinity of the enigmatic Devonian tubular fossil Trypanopora

The adult shell (teleoconch) of the enigmatic tubular Givetian fossil Trypanopora is comprised of two principal layers: an outer fibrous prismatic layer and an inner micro-lamellar (irregular cross-bladed) layer, with local, closely-spaced disruptive punctation. The fine preservation suggests an original calcite composition. The shell microstructure shows great similarities with that of both vermiform 'gastropods' and tentaculitoids, suggesting a close affinity between Trypanopora and these groups. The septa have an irregular micro-lamellar (cross-bladed) microstructure in continuity with the inner wall, and a morphology unlike that of any known mollusc. The class Tentaculitoidea is emended to include two new orders: Microconchida for the vermiform 'gastropods' and Trypanoporida for Trypanopora and allied genera. □ T rypanopora , microstructure, protoconch, teleoconch, fibrous prismatic layer, micro-lamellar layer, tubulation, septation, vermiform 'gastropods', Tentaculitoidea, Microconchida, Trypanoporida.