Two new species of <Emphasis Type="Italic">Gentianella</Emphasis> (Gentianaceae) from Peru

Two new species of Gentianella (Gentianaceae, Gentianeae, Swertiinae), G. grantii and G. wayqecha, are described from Departamento Cusco, Peru. These two species differ from other Peruvian species of Gentianella in a combination of stems 10–100 cm long; no rosette of basal leaves; cauline leaves 10–75 mm long; flowers in thyrses; and corollas 14–26 mm long, campanulate, and adaxially glabrous. The leaves of G. grantii consist of an appressed pseudopetiole and a spreading, narrowly elliptic-oblong to linear blade; the corollas are lavender; and the corolla lobes are 0.6–0.7× as long as the tube. Gentianella grantii is similar to G. lythroides, of Bolivia, but differs in having more closely spaced leaves and less deeply lobed corollas. The leaves of G. wayqecha are sessile, lanceolate to ovate; the corollas are rose-violet; and the corolla lobes are 0.75–1.35× as long as the tube. Gentianella wayqecha is similar to G. rapunculoides, of Colombia and Ecuador, and G. ruizii, of Peru, but differs from both in its adaxially glabrous corollas and from G. rapunculoides in its less deeply lobed corollas. Both G. grantii and G. wayqecha grow in moist habitats near tree line, and are known only from a area northeast of the city of Cusco.     

Long corollas as nectar barriers in <Emphasis Type="Italic">Lonicera implexa</Emphasis>: interactions between corolla tube length and nectar volume

Long corollas are a classical example of nectar barriers, because they prevent undesired visitors from consuming the reward intended for more effective pollinators. As the investment in nectar barriers increases, flower attractiveness and nectar rewards may also increase to maintain loyal visitation of most effective pollinators; and flowers may become more prone to nectar robbing. We evaluated the effect of nectar barriers (corolla tube length), two related traits (nectar volume and upper lip size) and the associated risk of nectar robbing, on the fecundity of Lonicera implexa plants from three populations differing in the abundance of its most efficient pollinator, the hummingbird hawkmoth Macroglossum stellatarum. Corolla tube length varied most among individuals within populations (45–46 % of total variance) and inflorescences within individuals (23–32 %), and showed little variation among populations (0.2–11 %). Longer corolla tubes were always associated with larger nectar volumes and larger upper lips, although the strength of the relationships varied across populations and years. Robbing frequency increased with corolla tube length, decreased with nectar volume and upper lip size, and its weak effects on fecundity were predominantly positive. Plant fecundity peaked at two different optima: long corollas with little nectar and short corollas with abundant nectar. However, the exact shape of the interaction between corolla length and nectar volume, as well as the combination of traits showing the highest fecundity, differed between populations and years. This variation could be explained by among-population differences in pollinator assemblages, and inter-annual changes in resources dedicated to reproduction. Our study shows that large nectar volumes can modulate the effect of corolla length as a nectar barrier, and that the combination of these two traits that maximises fecundity may be related to the identity of pollinators within each population.     

The relative strength of different floral visitors driving floral evolution within a <Emphasis Type="Italic">Primula secundiflora</Emphasis> population

Floral visitor assemblages within plant populations are usually composed of different visitors, and the relative abundance of these visitors also varies. Therefore, identifying the relative strength of these floral visitors driving floral evolution within the population is an important step in predicting the evolutionary trajectory of floral traits. Using supplemental hand pollination and nectar-robbing exclusion treatments, we experimentally identified the relative strengths of legitimate pollinators (that visit flowers through the corolla tube entrance) and nectar robbers (that visit flowers by biting a hole in the corolla tube or using an existing hole) driving floral evolution within the Primula secundiflora population. We also estimated legitimate pollinator- and nectar robber-mediated selection separately for pin and thrum flowers. Both legitimate pollinators and nectar robbers mediated selection on pollination efficiency traits in P. secundiflora population. Legitimate pollinators mediated selection for wider corolla tubes, whereas nectar robbers mediated selection for longer corolla tubes. In addition, nectar robber-mediated selection on corolla tube length marginally varied between the pin and thrum flowers. Nectar robber mediated selection for longer corolla tube length in the pin flowers not in the thrum flowers. These results indicate that legitimate pollinators and nectar robbers within a population can drive differential evolutionary trajectories of floral traits.     

Floral divergence and temporal pollinator partitioning in two synchronopatric species of <Emphasis Type="Italic">Vigna</Emphasis> (Leguminosae-Papilionoideae)

Exclusivity of pollinators, temporal partitioning of shared pollinators and divergence in pollen placement on the shared pollinators’ bodies are mechanisms that prevent interspecific pollen flow and minimize competitive interactions in synchronopatric plant species. We investigated the floral biology, flower visitors, pollinator effectiveness and seasonal flower availability of two syntopic legume species of the genus Vigna, V. longifolia and V. luteola, in ‘restinga’ vegetation of an island in southern Brazil. Our goal was to identify the strategies that might mitigate negative consequences of their synchronous flowering. Vigna longifolia and V. luteola were self-compatible, but depended on pollinators to set seeds. Only medium to large bees were able to trigger the ‘brush type’ pollination mechanism. Vigna longifolia, with its asymmetrical corolla and hugging mechanism, showed a more restrictive pollination system, with precise sites of pollen deposition/removal on the bee’s body, compared to V. luteola, with its zygomorphic corolla and cymbiform keel. There was a daily temporal substitution in flower visitation by the main pollinators. Vigna longifolia and V. luteola had overlapping flowering phenology but the densities of their flowers fluctuated, resulting in a seasonal partitioning of flower visitation. The differences in corolla symmetry and mainly the temporal partitioning among pollinators throughout the day and the flowering season proved to be important factors in maintaining the synchronopatry of V. longifolia and V. luteola.     

Effects of alien invasion by <Emphasis Type="Italic">Bombus terrestris</Emphasis> L. (Apidae) on the visitation patterns of native bumblebees in coastal plants in northern Japan

When alien pollinator species enter a native community of pollinators in which resource partitioning has been established, the pollination network between plants and pollinators may be modified through the interactions between the pollinators over the use of floral resources. We observed the floral-use patterns of native (Bombus hypocrita and B. deuteronymus) and alien (B. terrestris) bumblebee species in a coastal grassland in northern Japan. We analyzed the factors determining resource partitioning patterns. B. hypocrita tended to visit flowers with shallow or wide open corollas, such as Rosa rugosa, whereas B. deuteronymus visited flowers with complex or deeper corollas, such as Lathyrus japonicus. Given the wider floral preference of B. terrestris, floral use by the alien bumblebees consistently overlapped with that of native bumblebees. The visitation of B. terrestris to R. rugosa flowers was positively correlated with that of B. hypocrita. These bumblebee species frequently used similar floral resources, in part because of the large overlap in the seasonality of their foraging activity. The visitation frequency of B. deuteronymus to L. japonicus flowers was independent of the visitation frequency of other bumblebee species. The major visitation periods of the bumblebees to L. japonicus flowers reciprocally differed between B. deuteronymus and B. terrestris, suggesting phenological resource partitioning between these species. Our study suggests that phenological niche partitioning is more common in specialized flowers (L. japonicus) than in generalized flowers (R. rugosa).     

Evolutionary correlation between floral monosymmetry and corolla pigmentation patterns in <Emphasis Type="Italic">Rhododendron</Emphasis>

Floral symmetry and pigmentation are features of flowers that are believed to be associated due to their shared influence on pollinator behaviour. However, the evolution of such associations has so far not been examined. We analysed variation in Rhododendron flowers, in a phylogenetic context, to test whether the evolution of floral symmetry types and pigment patterns are correlated. Variation in floral symmetry due to variation in corolla form, stamen flexion, stamen arrangement, pistil flexion, as well as corolla pigment patterns was documented in 98 species of Rhododendron. Phylogenetic relations among these species were estimated using maximum likelihood (ML) and Bayesian methods, building on a published molecular dataset of sequences of RNA Polymerase II subunit (RPB2-I). Evolution of the floral traits was studied using phylogenetic correlation tests and ancestral state reconstructions (maximum parsimony, MP and ML methods). Significant correlations were found between corolla pigment pattern and type of floral symmetry at the level of corolla form, stamen flexion or arrangement, and pistil flexion. As expected from their similar roles in enhancing attractability to pollinator, monosymmetric corollas and presence of pigment pattern are correlated; in addition, monosymmetry involving other whorls too shows such a relationship with pigment patterns, and with each other. Multiple evolutionary shifts were detected between monosymmetry and polysymmetry of floral traits in Rhododendron. The relationship between floral monosymmetry attributes and presence of corolla pigment patterns, and additionally, frequent evolutionary shifts in these traits suggest pollinator-mediated selective pressures in Rhododendron.     

A new species of Drymonia (Gesneriaceae) from the eastern slopes of the Ecuadorian Andes

A new species, Drymonia ignea (Gesneriaceae, tribe Episcieae), is described from the eastern slopes of the Ecuadorian Andes from the provinces of Tungurahua, Napo, and Morona-Santiago. It differs from other species of Drymonia by the presence of an urceolate corolla, quadrangular stem, and cucullate calyx lobes.     

Floral micromorphology of the Australian carnivorous bladderwort <Emphasis Type="Italic">Utricularia dunlopii</Emphasis>, a putative pseudocopulatory species

Flowers of sexually deceptive taxa generally possess a set of morphological and physiological characters that mimic their insect pollinators. These characters often include a specific insect-like floral configuration, together with scent glands (osmophores) that produce fragrances which chemically resemble insect sex pheromones. Furthermore, these flowers tend not to produce pollinator food rewards. According to some authors, flowers of the Australian bladderwort Utricularia dunlopii (and species of the Utricularia capilliflora complex) resemble insects, and pollination perhaps occurs by pseudocopulation. The aims of this paper are to compare the structure and distribution of floral glandular trichomes in the Australian carnivorous plant U. dunlopii with those of closely related species assigned to the same section and to discuss their putative function. Floral tissues of U. dunlopii P. Taylor, Utricularia paulinae Lowrie, Utricularia dichotoma Labill. and Utricularia uniflora R.Br. (section Pleiochasia) were investigated using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. In U. dunlopii, two long, erect, filiform appendages arising from the upper lip of the corolla, together with three arising from the lower lip, bear numerous glandular trichomes that may function as osmophores. In other species, such as U. uniflora and U. paulinae, glandular papillae on the corolla palate may also function as osmophores. The floral anatomical and morphological organisation of U. dunlopii differs from that of the other investigated species, indicating that its insect pollinators are also likely to differ. Morphological and ultrastructural observations, while generally contributing to our understanding of the flower of U. dunlopii, do not refute the possibility that pollination here may occur by pseudocopulation. Further field-based investigations, however, are now necessary to test this hypothesis.     

Bee- to bird-pollination shifts in <Emphasis Type="Italic">Penstemon</Emphasis>: effects of floral-lip removal and corolla constriction on the preferences of free-foraging bumble bees

Plants might be under selection for both attracting efficient pollinators and deterring wasteful visitors. Particular floral traits can act as exploitation barriers by discouraging the unwelcome visitors. In the genus Penstemon, evolutionary shifts from insect pollination to more efficient hummingbird pollination have occurred repeatedly, resulting in the convergent evolution of floral traits commonly present in hummingbird-pollinated flowers. Two of these traits, a reduced or reflexed lower petal lip and a narrow corolla, were found in a previous flight-cage study to affect floral handling time by bumble bees, therefore potentially acting as “anti-bee” traits affecting preference. To test whether these traits do reduce bumble bee visitation in natural populations, we manipulated these two traits in flowers of bee-pollinated Penstemon strictus to resemble hummingbird-adapted close relatives and measured the preferences of free-foraging bees. Constricted corollas strongly deterred bee visitation in general, and particularly reduced visits by small bumble bees, resulting in immediate specialization to larger, longer-tongued bumble bees. Bees were also deterred—albeit less strongly—by lipless flowers. However, we found no evidence that lip removal and corolla constriction interact to further affect bee preference. We conclude that narrow corolla tubes and reduced lips in hummingbird-pollinated penstemons function as exploitation barriers that reduce bee access to nectaries or increase handling time.     

<Emphasis Type="Italic">Phragmidium</Emphasis> species parasitizing species of Rosaceae in Tibet,China, with descriptions of three new species

Phragmidum spp. are rust fungi that are serious pathogens of plants in the Rosaceae. We characterized 15 Phragmidium species from Tibet, including 12 previously described and 3 new species. All the taxa, including the three new species (Ph. chayuensis, Ph. cibanum, Ph. zangdongii) are described and illustrated based on morphological characteristics. These taxa have multi-celled teliospores with firm pedicels. Phragmidium chayuensis is characterized by (5)7–9-celled teliospores with short papillae. Phragmidium cibanum is characterized by smooth teliospores that are distinctly constricted at the septa. Phragmidium zangdongii is characterized by large uredinia and 11–13-celled teliospores. Five types of urediniospore-surface structures were identified based on the gross shape of ornamentations and their distribution on the urediniospore wall. Molecular sequence data from the LSU rDNA analysis showed that the new taxa formed distinct clades independent from previously recorded species represented by LSU rDNA sequence data. The phylogenetic tree indicated that Phragmidium species are highly host specific.     

Structure of the stigma and style of <Emphasis Type="Italic">Callaeum psilophyllum</Emphasis> (Malpighiaceae) and its relation with potential pollinators

The family Malpighiaceae, particularly in the Neotropic, shows a similar floral morphology. Although floral attraction and rewards to pollinators are alike, stigmas and styles show more diversity. The stigmas were described covered with a thin and impermeable cuticle that needs to be ruptured by the mechanical action of the pollinators. However, this characteristic was only mentioned for a few species and the anatomy and ultrastructure of the stigmas were not explored. In this work, we analyze the morphology, anatomy, and ultrastructure of the stigma and style of Callaeum psilophyllum. Moreover, we identify the potential pollinators in order to evaluate how the disposition of the stigmas is related with their size and its role in the exposure of the receptive stigmatic surface. Our observations indicate that Centris flavifrons, C. fuscata, C. tarsata, and C. trigonoides are probably efficient pollinators of C. psilophyllum. The three stigmas are covered by a cuticle that remained intact in bagged flowers. The flowers exposed to visitors show the cuticle broken, more secretion in the intercellular spaces between sub-stigmatic cells and abundant electron-dense components inside vacuoles in stigmatic papillae. This indicates that the stigmas prepares in similar ways to receive pollen grains, but the pollinator action is required to break the cuticle, and once pollen tubes start growing, stigmatic and sub-stigmatic cells release more secretion by a granulocrine process.     

Differential gender selection on flower size in two Neotropical savanna congeneric species

Larger flowers greatly increase among-individual pollen exchange within populations. However, water costs associated to transpirational cooling also increase with increasing flower size. Overall, the interplay between pollen and resource limitation determines the intensity of selection on flower size and this process is mostly dependent on gender and ecological context. To examine how pollinators and water use affect flower size, we determined corolla transpiration, pollen limitation, and selection through male and female fitness in two Kielmeyera species from the Brazilian cerrado flowering at different seasons. Hand-pollination experiments suggested pollen limitation through female fitness in both species, but K. coriacea showed lower limitation levels than K. regalis. For male fitness, the percentage of pollen removal was 1.5-times higher in K. coriacea. Higher air temperature and water deficit during flowering season of K. coriacea resulted in 4-fold higher corolla transpiration rates compared to K. regalis. Selection on flower size through male function was positive and significantly higher than selection through female components in both species. We also detected stabilizing selection in K. coriacea and positive selection in K. regalis on flower size through seed number. Our results suggest that selection on flower size in K. coriacea was mainly limited by water, whereas in K. regalis it was more limited by pollen. We demonstrate that differences in pollen and abiotic resource limitation determine gender-specific selection on flower size.     

In vitro inhibition of incompatible pollen tubes in <Emphasis Type="Italic">Nicotiana alata</Emphasis> involves the uncoupling of the F-actin cytoskeleton and the endomembrane trafficking system

In the S-RNase-based self-incompatibility system, subcellular events occurring in the apical region of incompatible pollen tubes during the pollen rejection process are poorly understood. F-actin dynamics and endomembrane trafficking are crucial for polar growth, which is temporally and spatially controlled in the tip region of pollen tubes. Thus, we developed a simple in vitro assay to study the changes in the F-actin cytoskeleton and the endomembrane system at the apical region of incompatible pollen tubes in Nicotiana alata. Growth but not germination of pollen tubes of S _c10 -, S ₇₀ -, and S ₇₅ -haplotypes was selectively inhibited by style extracts carrying the same haplotypes. Pollen F-actin cytoskeleton and endomembrane system, visualized by fluorescent markers, were normal during the initial 60 min of pollen culture in the presence of compatible and incompatible style extracts. Additional culture resulted in complete growth arrest and critical alterations in the integrity of the F-actin cytoskeleton and the endomembrane system of incompatible pollen tubes. The F-actin ring and the V-shaped zone disappeared from the apical region, while distorted F-actin cables and progressive formation of membrane aggregates evolved in the subapical region and the shank. The vacuolar network of incompatible pollen tubes invaded the tip region, but vacuolar membrane integrity remained mostly unaffected. The polar growth machinery of incompatible pollen tubes was uncoupled, as evidenced by the severe disruption of colocalization between the F-actin cytoskeleton and the endomembrane compartments. A model of pollen rejection integrating the main subcellular events occurring in incompatible pollen is discussed.     

Pollination-system diversity in <Emphasis Type="Italic">Epipactis</Emphasis> (Orchidaceae): new insights from studies of <Emphasis Type="Italic">E. flava</Emphasis> in Thailand

The rewarding orchid Epipactis flava was studied in NW Thailand. Its flowers were visited by a wide range of insects, most of which served as pollinators. The most frequent pollen bearers were (in decreasing order): the cricket Homoeoxipha lycoides, stingless bees of the Tetragonula testaceitarsis/hirashimai complex, hoverflies of subfam. Syrphinae, the wasp Polybioides gracilis and sweat bees of subfam. Halictinae. We found no evidence of a link between the rheophytic habit of E. flava and its pollinator fauna. Whereas most pollinators visited the flowers to feed on nectar, females of Episyrphus alternans (Syrphidae: Syrphinae) were observed to oviposit despite the absence of prey for their young. Hence, we suggest that dual pollination systems contribute to the opportunist strategy of E. flava, and we discuss, in a phylogenetic framework, how the strategy fits in with those previously reported for Epipactis sect. Arthrochilium. The elastic attachment of the epichile (a universal trait in sect. Arthrochilium) was found to promote outcrossing, and we hypothesize that loss of the elastic hinge has provided a key innovation facilitating recurrent evolution of obligate autogamy in sect. Epipactis (which is nested in sect. Arthrochilium).     

Comparative analysis of otolith morphology in three species of <Emphasis Type="Italic">Scomber</Emphasis>

Geometric morphometrics is a quick and reliable approach to differentiate fish stocks based on the variation of otolith shapes. In this study, morphometric analysis of otolith shapes was used to differentiate three species of Scomber. The sagittae morphology of S. scombrus otolith is totally different from that of S. japonicus and S. australasicus. Multivariate analysis consistently showed that S. japonicus was morphologically similar to S. australasicus, whereas a significant difference in otolith shapes was detected between S. scombrus and other two species of Scomber. The rostrum, antirostrum, excisural notch and dorsal-posterior margin of the otolith reflect the main variations between the three species of Scomber. Shape indices and Fourier coefficients were used to discriminate fish species using analysis of variance and Fisher discriminant analysis. The shape indices successfully differentiated 100%, 95.7% and 96.4% of otoliths in S. japonicus, S. australasicus and S. scombrus, respectively, while the Fourier coefficients only discriminated 70.0%, 61.9% and 91.3% of the sagittae in S. japonicus, S. australasicus and S. scombrus. This study indicates that the shape analysis on the sagittae morphometrics of otoliths is a better method to differentiate species of Scomber.     

Bee pollination and evidence of substitutive nectary in <Emphasis Type="Italic">Anadenanthera colubrina</Emphasis> (Leguminosae-Mimosoideae)

Anadenanthera colubrina (Vell.) Brenan (Leguminosae-Mimosoideae) is a widely-distributed tree in seasonally dry tropical forests of South America that was classified previously as lacking nectaries. However, some studies have stated that its flowers produce nectar, while others analyzed the composition of unifloral honey produced from A. colubrina flowers, raising the question about nectar production in the species. We studied the pollination and reproductive biology of A. colubrina var. cebil (Griseb.) Altschul in a natural population in the Caatinga, northeastern Brazil. Reproductive phenology, sexual system, floral biology, resource, and pollinators were investigated. We analyzed the breeding system through controlled pollinations for addressing its dependence on pollen vectors for reproduction. Anadenanthera colubrina flowered in the dry season, flower heads are heteromorphic, with staminate flowers at the base and perfect flowers at the apex of the inflorescence, characterizing andromonoecy. Anthesis is diurnal. We observed small drops of nectar at the apex of the petals of some flowers per inflorescence. Together with observations on flower visitor behavior and histochemical tests, we propose that A. colubrina produces floral nectar at the apex of the corolla, characterizing a substitutive nectary (sensu Vogel). This is the first record of substitutive nectary in the Mimosoideae and the first record of andromonoecy in the genus. Bees were the main pollinators (higher frequency), although other insects such as wasps, butterflies, and small beetles were also observed collecting nectar and/or pollen. The species is self-incompatible, thus depending on insect pollen vectors, mainly bees, for reproduction.     

Genetic diversity of free-living <Emphasis Type="Italic">Symbiodinium</Emphasis> in the Caribbean: the importance of habitats and seasons

Although reef corals are dependent of the dinoflagellate Symbiodinium, the large majority of corals spawn gametes that do not contain their vital symbiont. This suggests the existence of a pool of Symbiodinium in the environment, of which surprisingly little is known. Reefs around Curaçao (Caribbean) were sampled for free-living Symbiodinium at three time periods (summer 2009, summer 2010, and winter 2010) to characterize different habitats (water column, coral rubble, sediment, the macroalgae Halimeda spp., Dictyota spp., and Lobophora variegata, and the seagrass Thalassia testudinum) that could serve as environmental sources of symbionts for corals. We detected the common clades of Symbiodinium that engage in symbiosis with Caribbean coral hosts A, B, and C using Symbiodinium-specific primers of the hypervariable region of the chloroplast 23S ribosomal DNA gene. We also discovered clade G and, for the first time in the Caribbean, the presence of free-living Symbiodinium clades F and H. Additionally, this study expands the habitat range of free-living Symbiodinium as environmental Symbiodinium was detected in T. testudinum seagrass beds. The patterns of association between free-living Symbiodinium types and habitats were shown to be complex. An interesting, strong association was seen between some clade A sequence types and sediment, suggesting that sediment could be a niche where clade A radiated from a free-living ancestor. Other interesting relationships were seen between sequence types of Symbiodinium clade C with Halimeda spp. and clades B and F with T. testudinium. These relationships highlight the importance of some macroalgae and seagrasses in hosting free-living Symbiodinium. Finally, studies spanning beyond a 1-yr cycle are needed to further expand on our results in order to better understand the variation of Symbiodinium in the environment through time. All together, results presented here showed that the great diversity of free-living Symbiodinium has a dynamic distribution across habitats and time.