Comparative palynology and seed morphology in annual pansies (Viola sect. Melanium,Violaceae): implications for species delimitation

Abstract

This integrated study provides new insights into pollen and seed morphology and pollen heteromorphism of four closely related annual taxa of Viola sect. Melanium. The plant material, both fresh and dried, was collected in Italy and studied using light and scanning electron microscope. Palynological data for V. hymettia together with a detailed comparative analysis of seed morphology and micromorphology of the four species are reported for the first time. Results of this work highlight some pollen and seed features as useful diagnostic characters. The pollen size proves to be of diagnostic value to easily separate V. kitaibeliana, having the smallest pollen grains, from the others, especially from V. arvensis with the largest ones. Exine ornamentation is microreticulate, showing no relevant differences among species. We can partially confirm the diagnostic value of the prevailing pollen morph as it can be useful only for V. arvensis (five-aperturate) versus V. tricolor and V. hymettia (four-aperturate). The macro- and micromorphology of seeds provide additional useful distinguishing characters. Particularly, seed size was found to be a good delimitating character, especially to distinguish V. kitaibeliana (with the smallest seeds) from V. arvensis, and easy to be measured with no need of particular equipment.     

Biogeography and evolution of flower color in Veratrum (Melanthiaceae) through inference of a phylogeny based on multiple DNA markers

Veratrum (Melanthiaceae) comprises ca. 27 species with highly variable morphology. This study aims to construct the molecular phylogeny of this genus to infer its floral evolution and historical biogeography, which have not been examined in detail before. Maximum parsimony, maximum likelihood, and Bayesian analyses were performed on the separate and combined ITS, trnL-F, and atpB-rbcL sequences to reconstruct the phylogenetic tree of the genus. All Veratrum taxa formed a monophyletic group, within which two distinct clades were distinguished: species with white-to-green perianth formed one highly supported clade, and the species with black-purple perianth constituted another highly supported clade. Phylogenetic inference on flower color evolution suggested that white-to-green perianth was a plesiomorphic state and black-purple perianth was apomorphic for Veratrum. When species distribution areas were traced as a multi-state character, parsimonious optimization inferred that Veratrum possibly originated in East Asia. Our study confirmed previous phylogenetic and taxonomic suggestions on this genus and provided a typical example of plant radiation across the Northern Hemisphere.     

Dispersione anemofila di polline in Valle Padana

Abstract

Anemophylus dispersal of pollen grains in the Po Valley.—Results of phenological and aerobiological measurements with Castanea sativa pollen are presented. The data concerning the dispersal of this pollen in the Po Valley, show some features of the transport over hundred kilometer distances and give useful suggestions for application research.     

Palaeovegetational reconstruction based on pollen and seeds/fruits from a Bronze Age archaeological site in Tuscany (Italy)

Abstract

A reconstruction of the vegetation surrounding the Bronze Age archaeological site of San Lorenzo a Greve (Florence) based on pollen and seed/fruit records is presented. Pollen analysis suggests the presence of prevailingly open and damp landscapes, typically occurring on alluvial soils. Patches of woodland, mostly formed by deciduous Quercus, Ulmus, Salix, were alternated to the grasslands. Vitis also probably grew in these damp thickets together with Alnus and Hedera. The forests on the hilly slopes included deciduous Quercus, Carpinus betulus, Corylus, Cornus mas, and Sambucus nigra. Where the soil was well drained, Ostrya carpinifolia and Mediterranean evergreen elements such as Q. ilex and Viburnum tinus grew. In the landscape scenario reconstructed by pollen analysis, seeds/fruits indicated the presence of specific plants which produce a low amount of pollen: they are seldom recorded in pollen spectra but their fruits were commonly gathered in prehistory.     

Synopsis of the tribe Bocageeae (Annonaceae), with revisions of Cardiopetalum,Froesiodendron, Trigynaea,Bocagea, and Hornschuchia

The tribal name Bocageeae Endlicher is reestablished and the tribe is circumscribed on the basis of solitary internodal ebracteate pedicels that are articulated at the base, and pollen shed in polyads of eight or more grains. Septate anther locules, large pollen size, and seed appendages are prevalent in the tribe. Intectate pollen with free-standing columellae, rare in Annonaceae, occurs not only in the genusTrigynaea but also in some species ofBocagea andHornschuchia. As defined here, the Bocageeae include seven neotropical genera:Cymbopetalum, Porcelia, Bocagea, Cardiopetalum, Froesiodendron, Hornschuchia, andTrigynaea. The latter five genera are revised and the treatments include ten new species:Cardiopetalum plicatum, Froesiodendron urceocalyx, Hornschuchia lianarum, H. santosii, H. leptandra, Trigynaea cinnamomea, T. lanceipetala, T. triplinervis, T. lagaropoda, andT. axilliflora, all from tropical South America. A new combination,Froesiodendron longicuspe, changes the rank of that taxon from subspecies to species.Cardiopetalum surinamense is removed fromFroesiodendron and reassigned toCardiopetalum on the basis of its connate petals, dehiscent monocarps, and seeds with bilobed arils. A cladogram provides an explicit hypothesis of intergeneric relationships in the tribe. The new combinationOnychopetalum periquino, based onTrigynaea periquino, is made.     

The exceptionally diversified Neotropical genus Veturius Kaup: more new data on its phylogeny,taxonomy and distribution (Coleoptera: Passalidae)

New data are provided on 24 known and five new species in three subgenera of Veturius Kaup (Proculini), from Central and South America. Veturius s. str.: V. hincksi Boucher, 2006 (wing polymorphism, Colombia: Nariño), V. perecasi Boucher, 2006 (Colombia: Boyacá, Santander, perhaps Risaralda), V. montivagus Boucher, 2006 (first precise location, Colombia: Tolima), V. schusteri Boucher, 2006 (Costa Rica: Guanacaste, Cartago, Alajuela), V. platyrhinus (Hope & Westwood, 1845) (Colombia: Tolima), V. aspina Kuwert, 1898 (polymorphism, Colombia: Sucre, Cesar, Córdoba, Antioquia), V. yahua Boucher, 2006 (Colombia: Amazonas, Meta), V. ecuadoris Kuwert, 1898 (Colombia: Caquetá), V. muisca n. sp. (Colombia: Cundinamarca), V. nonuya Boucher & Salazar, n. sp. (Colombia: Amazonas), V. standfussi Kuwert, 1891 (polymorphism, Colombia: Caquetá; Peru: Piura), V. arawak Boucher, 2006 (Peru: Cuzco, Puno), V. fabieni Boucher & Salazar, n. sp. (Peru: Junín), V. dreuxi Boucher, 2006 (Bolivia). Publius Kaup: V. crassus (Smith, 1852) (Colombia: Cundinamarca, Boyacá, Meta, perhaps Tolima), V. rugifrons Boucher, 2006 (Colombia: Cundinamarca, Boyacá), V. concretus (Kaup, 1868) (Colombia: Cundinamarca, Boyacá, Meta), V. tectus Boucher, 2006 (second record, Colombia: Santander), V. dupuisi Boucher, 2006 (second record, Colombia: Cundinamarca), V. centralis Boucher, 2006 (second record, Colombia: Antioquia), V. taurus Boucher, 2006 (second record, Colombia: Norte de Santander), V. spinipes Zang, 1905 (topotype, Bolivia). Ouayana Boucher: V. paraensis Luederwaldt, 1927 (Brazil, Pará), V. negroensis Boucher, 2006 (Colombia: Vaupés; Brazil: Amazonas), V. amazonicus Boucher, 2006 (Colombia: Guainía), V. quaesitor Boucher & Salazar, n. sp. (Peru: Piura), V. uncinatus n. sp. (Colombia: no other indication), V. casalei Boucher, 2006 (Colombia: first precise location, Caldas, Antioquia), V. fanestus Boucher, 2006 (Colombia: Nariño). Veturius contains now 86 species, and is by far the most diversified recognized monophyletic genus in the Passalidae.     

Pollen dispersal and fruit production in Vaccinium oxycoccos and comparison with its sympatric congener V. uliginosum

Investigating plant–pollinator interactions and pollen dispersal are particularly relevant for understanding processes ensuring long‐term viability of fragmented plant populations. Pollen dispersal patterns may vary strongly, even between similar congeneric species, depending on the mating system, pollinator assemblages and floral traits. We investigated pollen dispersal and fruit production in a population of Vaccinium oxycoccos, an insect‐pollinated shrub, and compared the pollen dispersal pattern with a co‐flowering, sympatric congener, V. uliginosum. We examined whether they share pollinators (through interspecific fluorescent dye transfers) and may differently attract pollinators, by comparing their floral colour as perceived by insects. Fluorescent dyes were mainly dispersed over short distances (80% within 40.4 m (max. 94.5 m) for V. oxycoccos and 3.0 m (max. 141.3 m) for V. uliginosum). Dye dispersal in V. oxycoccos was not significantly affected by plant area, floral display or the proximity to V. uliginosum plants. Interspecific dye transfers were observed, indicating pollinator sharing. The significantly lower dye deposition on V. oxycoccos stigmas suggests lower visitation rates by pollinators, despite higher flower density and local abundance. The spectral reflectance analysis indicates that bees are unlikely to be able to discriminate between the two species based on floral colour alone. Fruit production increased with increasing floral display, but was not affected by proximity to V. uliginosum plants. Our study highlights that fragmented populations of V. oxycoccos, when sympatric with co‐flowering V. uliginosum, might incur increased competition for the shared pollinators in the case of pollination disruption, which might then reduce outcrossed seed set.     

Pollen structure and germination of Crocus thomasii Ten. (Iridaceae)

Abstract

Mature pollen of C. thomasii Ten. (Iridaceae) has been studied from a morphological and physiological point of view and compared to that of C. sativus L., C. thomasii pollen is roundish, with a 83 μm diameter and a 14% of anomalous grains. Percentage of the positive alcoholdehydrogenase (ADH +) pollen grains is about 90% whereas the in vitro germinated rate reaches 55%. Exine is homogeneously thickened (2.5 μm) with randomly distributed thinner zones and 5 μm thick intine. Cytoplasm of vegetative and generative cells is very rich of small and large smooth vesicles and vesicles coated by ribosomes. The generative cell shows a thin ondulated pectocellulosic wall. Its nucleus is intensely fluorescent after treatment with the 4,6-diamidino-2-phenylindole (DAPI) fluorochrome. Although many ultrastructural aspects of the C. thomasii pollen are common in C. sativus. L., C. thomasii pollen is smaller, more regularly structured and germinates in vivo and in vitro in higher percentage than that of C. sativus.     

La composizione chimica dell'essudato stigmatico di Citrus limon (L.) Burm

Abstract

The composition of the stigmatic exudate of Citrus limon (L.) Burm. - Biochemical analyses of the stigmatic exudate of Citrus limon (L.) Burm. have revealed the presence of lipids, polysaccharides, proteins, phenols, free aminoacids and alkaloids. The role of stigma secretion is discussed in relation to pollen activation and recognition and the pollen tube growth.     

A new Veturius (Veturius) of the “cephalotes” group from southern Colombia,Putumayo (Coleoptera: Passalidae)

A new species of Veturius (Veturius) Kaup from southern Colombia, Putumayo, lowland forests, is described and illustrated. V. paya n. sp. belongs to the South American “cephalotes” species group and is sister species of V. cephalotes (Le Peletier & Serville, 1825). Both species are distinguished by few characters of the head and thorax. They seem to be allopatric close to the western distributional limits of V. cephalotes. The endemism of V. paya n. sp. corresponds to a geographic vicariance in the axis of the Amazon Basin. An overview is given on the phylogeny and the chorology of the completed “cephalotes” species group.     

A Structure‐Activity Relationship between the Veratrum Alkaloids on the Antihypertension and DNA Damage Activity in Mice

Veratrum plant contains a family of compounds called steroidal alkaloids which have been previously reported to cause DNA damage and blood pressure decrease in vivo. In this study, the antihypertensive effects and DNA damage in brain cells of 12 steroidal alkaloids separated from Veratrum plant were all evaluated to develop a relationship among chemical structure, antihypertensive activity and neurotoxicity by utilization of chemical principal component analysis (PCA) and hierarchical cluster analysis (HCA). Twelve steroidal alkaloids markedly reduced high blood pressure of hypertensive mice and also similarly induced varying degrees of DNA single‐strand breaks in mouse cerebellum and cerebral cortex after oral administration. On the basis of the PCA and HCA results, it was suggested that the 3‐carboxylic esters and benzene group play a core role in the DNA damage of brain cells, while more hydroxy groups in the A‐ring and B‐ring structure of jervine‐type alkaloid led to stronger antihypertensive activity. The primary structure, activity and neurotoxicity relationship were discussed briefly.     

Insight into “serpentine syndrome” of Albanian,endemic violets (Viola L., Melanium Ging. section) – Looking for unique,adaptive microstructural floral,and embryological characters

The genus Viola, particularly Melanium section, rich in metallophytes, is an excellent taxon for study of microevolutionary and adaptation processes. Pollen, ovule, and microstructural floral characters were investigated by LM, SEM, and CLSM in seven endemic Albanian violets, five serpentinophytes (Viola albanica, V. dukadjinica, V. albanica × V. dukadjinica, V. raunsiensis, and V. macedonica), two from chalk soil (V. aetolica and V. schariensis), and in their closest relatives (V. lutea ssp. sudetica, V. tricolor ssp. tricolor, and V. arvensis) for their taxonomic usefulness and adaptive value. Three among analyzed characters were common in all Albanian violets however not unique. Serpentinophytes, V. aetolica and V. schariensis possessed hairs deep inside the spur, developed pollen heteromorphism, both increase the chance of pollination in unpredictable conditions and had strongly developed tannin rich layer in the outer integument of the young ovules with a protective role. They also all exhibited high pollen viability (86.9 ± 10.2%), high frequency of normally developed, enlarged (fertilized) ovules in ovary (65.0 ± 24.0%), but also high frequency of degenerations in developing ovules (40.4 ± 9.8%). Several flower characters may be adaptive in the unfavorable, high altitude environment, including serpentine soils. High pollen viability and normally developed fertilized ovules are sufficient for Albanian species maintenance.     

A nodding capitulum enhances the reproductive success of Cremanthodium campanulatum (Asteraceae) at high elevations in the Sino–Himalayan Mountains

Background: Flower orientation is considered an evolutionary response to pollinators and abiotic factors. Several members of the genus Cremanthodium (Asteraceae) growing in alpine habitats in the Sino–Himalayas have conspicuously nodding capitula, the function of which is not understood.

Aims: We investigated the influences of nodding capitula on floral thermal conditions, pollinator visitation rate, pollen viability and achene production in Cremanthodium campanulatum.

Results: (1) the nodding capitulum did not modify internal thermal conditions, but the elongated involucral bracts could shelter pollen from UV-B radiation; (2) water and UV-B radiation seriously reduced the viability of pollen grains; (3) capitula artificially held erect set significantly fewer achenes than nodding ones; and (4) no pollinator preference was observed between capitula that were artificially held erect and natural nodding ones.

Conclusions: This study indicated that the nodding capitulum of C. campanulatum may protect pollen from being damaged by UV-B radiation, being washed away from the anther and stigma, and enable it to avoid rain damage during the wet monsoonal period. Our results suggest that nodding capitula in C. campanulatum possibly confer a selective advantage and may be driven by non-biological agents rather than pollinator attractors.     

Pollen packaging and dispensing: adaption of patterns of anther dehiscence and flowering traits to pollination in three Epimedium species

Pollen presentation theory (PPT) predicts that plant species typically pollinated by frequent and wasteful pollinators ought to be much more parsimonious and only gradually release pollen compared to plant species pollinated by infrequent pollinators that are efficient at delivering the pollen they remove. To test PPT, we compare the pollen presentation schedules and pollination systems in three related Epimedium species, having different pollinators. Results showed that differences in anther dehiscence and flowering traits resulted in different pollen packaging schedules. For E. sutchuenense and E. franchetii, a special ‘roll‐up’ movement of the anther wall during anther dehiscence increased pollen removal compared to the dehiscence pattern in E. mikinorii, which lacked the ‘roll‐up’ movement. Investigations revealed that honeybees had a higher pollen removal rate and lower stigmatic pollen load compared to bumblebees. In accordance with PPT, E. sutchuenense presents pollen sequentially and slowly for the frequent and wasteful honeybees. In comparison to E. sutchuenense, E. franchetii had a faster presentation rate and was adapted to the efficient and infrequent bumblebees. However, E. mikinorii was pollinated by both bumblebees and honeybees at high frequency and had the fastest pollen presentation. This pattern could reduce pollen wastage by honeybees and might be an adaptation to its short flower longevity (less than 1 day), to increase the chances of pollen deposition on stigmas. The study indicates that pollen presentation schedules can be a consequence of interactions among anther dehiscence, flowering traits and pollination environments for a given species.     

Facilitation by unpalatable weeds may conserve plant diversity in overgrazed meadows in the Caucasus Mountains

Positive interactions among plants have been demonstrated in many communities around the world, and appear to play important roles in maintaining species coexistence, productivity, and species diversity. However, the potential for positive interactions to conserve biological diversity in ecosystems that are disturbed by humans is poorly understood and often overlooked. One of the most important positive effects one plant can have on another is protection from herbivory. By associating with an unpalatable neighbor, a tasty species may avoid being eaten and increase in size and reproductive fitness. We examined the role of two highly unpalatable plants, Cirsiumobvalatum and Veratrum lobelianum, in subalpine meadow plant communities of the central Caucasus Mountains in the Republic of Georgia, where intense livestock grazing has occurred for over two thousand years. These two species are avoided by livestock because of spines and toxicity, respectively, and have increased dramatically in abundance recently due to seasonal trans‐Caucasus migrations of vast herds of domestic sheep during the Soviet era. The Gudauri region, bisected by the Russian‐Georgian Military Road, was a focal point of these migrations, and there we found that plant communities associated with Cirsium and Veratrum were very different in composition than open meadows. Forty‐four percent (15/34) of all species at our site were found at only “trace” (<1.0%) cover values in the open meadow, but at significantly higher covers under Cirsium or Veratrum. Of the 38 species that were reproducing sexually at our site, eight were found only under the unpalatable invaders. Communities associated with Cirsium and Veratrum had 78–128% more species in flower or fruit than open meadow communities, respectively, than open meadow sites. Furthermore, community composition and reproductive output differed substantially between Cirsium and Veratrum, indicating some degree of species‐specificity in their effects. These results indicate that unpalatable plants, which are generally indicators of unhealthy rangelands, have the potential to preserve plant diversity in overgrazed plant communities.     

Cytinus hypocistis L. embryogenesis: Some biological and ultrastructural aspects of fertilization and embryo development

Abstract

The present paper examines some biological and ultrastructural aspects of fertilization and early development of the embryo in Cytinus hypocistis, a parasitic plant belonging to the Rafflesiaceae. The probable functions of a mucilaginous substance contained in the ovary and embedding the numerous pollen tubes coming from the style are discussed.

It was ascertained that pollen tubes pass through the micropyle and enter a synergid pushing, their way through the nucellar cells that show swollen walls owing to a probable enzymatic action whose function is to facilitate pollen tube penetration. It was hypothesized that the secretion of such enzymes is attributable to the numerous pollen present in the ovary or entering the mycropyle.

Since, in all the ovules observed, synergid degeneration was never found before the arrival of the pollen tube, this degeneration was interpreted as being caused by the material disharged by the pollen tube, rather than being an essential prerequisite for pollen tube penetration into the synergid.

Pollen tube content was observed to be made up of an intensely electron-dense substance surrounding many lipidic globules and numerous polysaccharide vesicles that fuse with the pollen tube wall, clearly contributing to its growth.

The sequence of the first divisions of the developing embryo was followed and the extreme reduction of the embryo is confirmed.

In Cytinus hypocistis starch is totally absent from all the sells belonging to the female gamethophyte as well as to those belonging to the embryo, but lipidic globules are very frequent; it is therefore supposed that these bodies constitute good material for the nutrition of the zygote and early embryo.     

Three new species of Philocorydoras Suriano, 1986 (Monogenoidea: Dactylogyridae) infecting the gills of callichthyids (Actinopterygii: Callichthyidae) from the Peruvian Amazonia

During a research on gill ectoparasites of callichthyids fishes from the Peruvian Amazonia, the following monogenoideans were found: Philocorydoras peruensis n. sp. from Corydoras splendens (Castelnau); Philocorydoras multiradiatus n. sp. and Philocorydoras jumboi n. sp. from Brochis multiradiatus (Orcés, V.). All new species described herein are mainly differentiated from their congeners based on the morphology of the copulatory complex. In P. peruensis n. sp. the cirrus is “J”-like shaped tube slightly tilted to one side, while in P. jumboi n. sp. is “J”-like shaped tube in a straight position and in P. multiradiatus n. sp. the cirrus is an arced tube with inflated base and distally narrow. Brochis (Orcés, V.) represents a new genus hosting species of Philocorydoras. All new species presented in this work represent the first species of Philocorydoras reported for Peru.

     

Further study on the phylogeny,taxonomy and distribution of the genus Veturius Kaup in Central and South America (Coleoptera: Passalidae)

This study provides data on the phylogeny, taxonomy and distribution of 14 known and five new species of the Neotropical genus Veturius Kaup (Proculini), belonging to various subgenera and species groups: V. (Veturius) latissimus n. sp. (Colombia, Central Andes) and V. (V.) calimanus n. sp. (Pacific slope of the Occidental Cordillera) are separated from V. (V.) caquetaensis Boucher, 1988, which seems restricted to the Amazonian slope of the Oriental Cordillera (Caquetá, Putumayo); V. (V.) sinuatomarginatus Luederwaldt, 1941 (Costa Rica), n. syn. of V. sinuatocollis Kuwert, 1890; V. sinuatocollis aculeatus Luederwaldt, 1941 (syntype from Costa Rica); V. (V.) aspina Kuwert, 1898 (located in Occidente of Ecuador, Guayaquil); V. (V.) yahua Boucher, 2006 (located in Occidente of Ecuador, Pichincha and SW Colombia, Nariño); V. (V.) guntheri Kuwert, 1898 (located in Peru, SE Puno and Colombia, W Putumayo); V. (V.) cephalotes (Le Peletier & Serville, 1825) (citation from Guyana); V. (V.) sinuatus (Eschscholtz, 1829) (previous synonymy); V. (V.) libericornis Kuwert, 1891 (located in Peru, Cuzco); V. (V.) lepidus Fonseca, 1999 (revision; located in Colombia, Amazonas, Putumayo and Peru, Loreto); V. (V.) transversus (Dalman, 1817) [syntype; previous synonymy of V. trituberculatus (Eschscholtz, 1829) with V. assimilis (Weber, 1801) and located in Brazil, Mato Grosso]; V. (V.) sinuosus (Drapiez, 1820) (corrected reference for Colombia); V. (Publius) crassus (Smith, 1852) (new syntype); V. (P.) danieli Boucher, 2006 (holotype deposit); V. (P.) vazdemelloi Boucher, n. sp. (Andes of Ecuador, Azuay); V. (Ouayana) unicornis Gravely, 1918 (located in Colombia, E Vaupés); V. (O.) costaianus Boucher, n. sp. (Venezuela, Amazonas, NW Pacaraima Massif); Ticoisthmus Boucher, n. subg., for the species group of V. (O.) laevior (Kaup, 1868), of southern Central America; and V. (T.) brachypterus Boucher, n. sp. (Costa Rica, Sierra Talamanca). Ticoisthmus is considered the sister group of Ouayana. It belongs to the Meso-American low mountain dispersion pattern and demonstrates, especially in the genus Veturius, but also more generally in the Neotropical passalids, the hot-spot characteristics, with diversity and endemism, of the narrow land between the Depression of Nicaragua and the Isthmus of Panama.