Leaf anatomical studies of Chamaecrista subsect. Baseophyllum (Leguminosae, Caesalpinioideae): new evidence for the up-ranking of the varieties to the species level

This study aims to determine whether morphoanatomical characters of the leaves of the species of Chamaecrista sect. Absus subsection Baseophyllum could be used to support an up-ranking of C. cytisoides varieties to the species level as previously defined by molecular studies. The significance of anatomical adaptive strategies to arid environments is also discussed. Standard light microscopy techniques and histochemical tests were used for both morphoanatomical and histochemical characterization of the leaves. All the species studied share a single-layered epidermis, actinodromous–camptodromous–brochidodromous type of venation, vascular bundles surrounded by layers of fibers bounded externally by a sheath of cells containing solitary crystals, enlarged tracheids at the vein endings, vascular petiole/rachis tissue with a parenchymatous pith, accessory vascular bundles, mucilage idioblasts and hypodermis in the mesophyll, colleters, and non-secretory trichomes. The position and type of stomata, type of mesophyll, number of palisade and spongy parenchyma layers, position of mucilage idioblasts in the mesophyll, and the number of accessory vascular bundles of petiole/rachis provided useful characters for discriminating the eight species of the subsect. Baseophyllum. Histochemical tests reveal the presence of total polysaccharides, pectins, mucilage and phenolic compounds in the idioblasts. Other xeromorphic characters such as thickened outer periclinal cell walls, compact mesophyll, mucilage idioblasts and hypodermis in the mesophyll may help enable the studied species to survive in exposed sunny areas.     

The oleoresin secretory system in seedlings and adult plants of copaíba (Copaifera langsdorffii Desf., Leguminosae-Caesalpinioideae)

The ecological and economic importance of oleoresin produced by Copaifera langsdorffii is well established. This study aims to investigate the ontogeny, anatomy and ultrastructure of the internal glands of C. langsdorffii during plant development. Samples were processed for light and electron microscopy and a specific technique was applied to impregnate endomembranes. Internal secretory glands were observed in the hypocotyl, epicotyl and eophylls of seedlings, and in the primary stem, pulvinus, petiole, rachis and leaf blade of adult plants. Canals and cavities show differential distribution. They arise from ground meristem cells, and the lumen is first formed by schizogenesis followed by later schizolysigenous development. The dense cytoplasm of epithelial cells shows mitochondria, plastids without thylakoids, polyribosomes and endoplasmic reticulum. A periplastidial reticulum was also observed. Secretion is released by eccrine, granulocrine and holocrine processes. Lipophilic and hydrophilic compounds were histochemically detected in both canals and cavities, whereas resin was detected only in canals. The presence of these substances has been associated with plants’ defences against dehydration, as well as against attacks from herbivores and pathogens, from seedling stage onwards.     

Leaf anatomy as an additional taxonomy tool for 16 species of Malpighiaceae found in the Cerrado area (Brazil)

This work describes the leaf anatomy of 16 species belonging to three genera of the Malpighiaceae family found in the Cerrado (Minas Gerais State, Brazil). The scope of this study was to support the generic delimitation by contributing to the identification of the species and constructing a dichotomous identification key that includes anatomical characters. The taxonomic characters that were considered to be the most important and used in the identification key for the studied Malpighiaceae species were as follows: the presence and location of glands; presence of phloem in the medullary region of the midrib; mesophyll type; presence and type of trichomes; and presence, quantity, and disposition of accessory bundles in the petiole. It was also possible to indicate promising characters for future taxonomic and phylogenetic studies in the Malpighiaceae family, especially for the Banisteriopsis, Byrsonima, and Heteropterys genera.     

Distribution and structural aspects of extrafloral nectaries in Cedrela fissilis (Meliaceae)

The occurrence of extrafloral nectaries (EFNs) in Meliaceae has been reported for some genera, but little anatomical data are available. Therefore, to determine the distribution and structural aspects of EFNs, Cedrela fissilis Vell. leaves in different stages of development were collected, fixed, and processed for light and scanning electron microscopy. On the petiole, rachis and petiolule, EFNs were found to be arranged predominantly towards the abaxial surface, while their occurrence in leaflet blades was restricted to the abaxial surface of the major veins, noticeably on the midrib. Basal leaflets displayed few EFNs; however, we observed an increase towards the leaf's apex. The leaf can contain more than 300 inconspicuous EFNs, which show secretory activity throughout the leaf's life. Two EFN morphotypes were visible: flattened or elevated, both circular or slightly elliptical and similar in origin and tissue composition. The secretory tissue is embedded in the rachis cortex or in the major veins of the leaf blade and EFNs are not vascularized. The EFN secretory pole shows a uniseriate epidermis with compactly arranged cells and a thin cuticle; stomata and trichomes are absent. The observation of ant visits at these structures reinforces the assumption that EFNs mediate ant–plant interactions and play a protective role against herbivores throughout the life of a leaf.     

Leaf anatomy of Ficus subsection Urostigma (Moraceae)

Species of Ficus subsection Urostigma show much overlapping variation in vegetative morphology, which often precludes correct identification of the species. The aim of this study was to describe the leaf anatomical characters and their variation and to check their suitability for identification. Included were 41 samples belonging to 25 species of subsection Urostigma, four samples belonging to two species of section Leucogyne and one specimen of Ficus glaberrima subsp. siamensis of subsection Conosycea. Transverse sections of lamina, midrib and petiole and cuticular macerations were used, and the observed anatomical characters are described for each species. On the basis of a limited number of studied samples, leaf anatomy shows little variation within each species and each species has a unique combination of character states, facilitating identification. Ficus arnottiana shows some leaf anatomical characters that are quite different from those of other members of subsection Urostigma, including a multiple epidermis and enlarged lithocysts on both sides of the leaf. Both characters are generally considered as typical for Ficus subsection Conosycea. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 259–281.     

Novel reports of glands in Neotropical species of Indigofera L. (Leguminosae,Papilionoideae)

By considering controversial discussions in the literature with regard to gland denomination in Indigofera species, as well as the taxonomic value of secretory structures in Leguminosae, we aim to morphologically detail glands that had been previously observed in I. microcarpa and I. sabulicola, and to investigate the occurrence of glands in vegetative and reproductive organs of other six Neotropical species that belong to the genus. Glands analyzed through scanning electronic microscopy (SEM) in combination with anatomic analyses correspond to secretory trichomes that are classified into seven types. Main variations in relation to types occurred with regard to head shape and peduncle size. Trichome heads were multicellular, with a thin cuticle. Hollow heads with conspicuous inner space characterized only one type (type 1); the other trichome types had massive heads. Peduncles, which varied from biseriate to multiseriate, had thick, pecto-cellulosic cell walls. Trichomes were found on stems, stipules, petioles, rachis, petiolules, leaflets, bracteoles, sepals, standards and fruits, more commonly along the margins. Each of the eight Indigofera species analyzed had at least two different trichome types out of the seven types that occurred in reproductive and vegetative organs of these taxa. Various types of secretory trichomes were found in I. campestris, I. lespedezioides, I. microcarpa, I. spicata, I. suffruticosa and I. truxillensis. Stems and rachis were the vegetative organs in which a greater variety of trichomes occurred, and sepals were parts of reproductive organs with the same status. Five out of the seven secretory trichome types occurred on both vegetative and reproductive organs. Distribution and gland types differed between species and these gland distribution patterns can be used as diagnostic characters. Reports of glands in Indigofera campestris, I. hirsuta, I. lepedezioides, I. suffruticosa, I. spicata and I. truxillensis, their recognition as secretory trichomes, and the morphological variety of types found for such trichomes are novel data for Indigofera.     

Distribution, structural and ecological aspects of the unusual leaf nectaries of Calolisianthus species (Gentianaceae)

Nectaries in leaves of Gentianaceae have been poorly studied. The present study aims to describe the distribution, anatomy, and ecological aspects of extrafloral nectaries (EFNs) of three Calolisianthus species and in particular the ultrastructure of EFNs in Calolisianthus speciosus during leaf development, discussing its unusual structure. Leaves of Calolisianthus species were fixed and processed by the usual methods for studies using light, scanning microscopy and transmission electron microscopy (TEM). Ion chromatography was used to analyze the nectar exudates of C. speciosus. The distribution patterns of nectar secretion units were analysed by ANOVA and t-tests. Two EFNs that can be seen macroscopically were observed at the bases of C. speciosus and C. pendulus leaves. Such large nectaries are absent there in C. amplissimus. Another similarly large EFN is observed at the apex of each leaf in all species. The EFNs at the base of the young leaves in C. speciosus are visited by ants during the rainy season. EFNs are formed by several nectar secretory units (nectarioles) that are present throughout the leaves. Each nectariole is formed by rosette cells with a central channel from which the nectar is released. Channels of old C. speciosus and C. pendulus EFNs were obstructed by fungi. TEM of EFNs in young leaves showed cytoplasms with secretion, small vacuoles, mitochondria, cell wall ingrowth, and plasmodesmata. TEM of EFNs in old leaves demonstrated dictyosomes, plastids, mitochondria, segments of endoplasmatic reticulum, and lipid droplets. The nectar contains sucrose, glucose and fructose.     

Chemosystematics of section Palaeonarthex of the Genus Ferula

Ferula species of the section Palaeonarthex contains various sesquiterpenoids. While C-15 terpenoid coumarins of the iresan type are the most characteristic constituents of species in the subsection Foetidissimae, sesquiterpene lactones and C-10 terpenoid coumarns are found in the subsection Tumidae and esters of the sesquiterpene alcohols in the subsection Jaeschkaenae. The biogenetic relationships of the Ferula sesquiterpenoids and their chemosystematic value are discussed.     

Koralionastetales, a new order of marine Ascomycota in the Sordariomycetes

Based on molecular studies using 1760 bp of the nuSSU and 604 bp of the nuLSU rRNA genes and using morphological characters, the genera Koralionastes and Pontogeneia are assigned to the new order Koralionastetales, family Koralionastetaceae, class Sordariomycetes. Koralionastetales is a sister group to Lulworthiales; differences in morphological characters are expressed in the ascospores and the presence/absence of periphyses and paraphyses. A new species of Pontogeneia, P. microdictyi from Microdictyon sp. in the Bahamas, is described.     

ORIGINAL ARTICLE: Cycads in the insular South‐west Pacific: dispersal or vicariance?

Aim Cycads constitute an ancient plant group that is generally believed to disperse poorly. However, one group of cycads (subsection Rumphiae) is thought to have dispersed relatively recently from a Malesian source area westwards to East Africa and eastwards into the Pacific, using a floatation‐facilitating layer in their seeds. We use morphological and allozyme characters to investigate the relationships among the species within this group and to deduce whether the wide distribution was achieved by recent dispersal (as evidenced by high genetic similarity) or more distant vicariance events (high genetic differentiation). Location We examined specimens collected throughout the range of subsection Rumphiae, from East Africa through Southeast Asia to Tonga in the South‐west Pacific. Methods We investigated relationships within subsection Rumphiae of the genus Cycas by analysing 18 variable (11 informative) morphological characters and 22 allozyme loci for seven of the 10 species currently assigned to this taxon. Results Distinctive morphological characters are few and fail to resolve relationships within the group. Allozyme data show that species within this subsection are closely related and suggest that there are two groups within the subsection, one comprising Cycas thouarsii (East Africa) and C. edentata (the Philippines), and the other the remaining species (from Malesia and the Pacific). The Australian species C. silvestris is sister to subsection Rumphiae in the morphological analysis but is closely allied to C. rumphii (nested within the subsection) in the allozyme analysis, suggesting that Rumphiae may be paraphyletic and that characters thought to be taxonomically important may need to be re‐evaluated. Main conclusions Cycads within subsection Rumphiae are closely related, and the wide distribution of this group was probably achieved through relatively recent oceanic dispersal events. Separate events probably account for the dispersal of these cycads into the Pacific and to Africa. The origin and distribution of C. silvestris (Australia) could be explained by a dispersal event from New Guinea or may have resulted from a former land connection between Australia and New Guinea.     

Genetic diversity and relationships among species of the genus Thymus L. (section Serpyllum)

Amplified fragment length polymorphism (AFLP) markers were used to assess genetic relations of 32 Thymus populations belonging to seven species of genus Thymus, section Serpyllum, from Serbia. The collected species belong to three subsections: (1) Alternantes Klokov (Th. pulegioides L.), (2) Isolepides (Borbás) Halácsy (Th. glabrescens Willd., Th. marschallianus Willd., Th. pannonicus All.), and (3) Pseudomarginati (Braun ex Borbás) Jalas (Th. balcanus Borbás, Th. moesiacus Velen., Th. praecox Opiz). Analysis of molecular variance (AMOVA) revealed that most of the genetic diversity was attributable to differences among individuals within populations, while the remaining variability was almost equally distributed among species and among populations within species. The pairwise AMOVA analyses further showed that species differentiation was significant in all cases, except between Th. marschallianus and Th. pannonicus. All the individuals belonging to Th. pulegioides (subsection Alternantes) formed a well-supported clade, the most divergent from all other species in this study. This genetic differentiation of Th. pulegioides is supported by its morphological features because it is the only analyzed taxon having hairs only on the stem edges, and can easily be recognized by this character. According to our results, the subsection Isolepides is polyphyletic. Th. glabrescens is clearly separated from the other two species of this subsection (Th. marschallianus, Th. pannonicus). Although morphologically distinguishable by leaf indumentum, individuals belonging to Th. marschallianus and Th. pannonicus could not be differentiated at the molecular level. The species belonging to subsection Pseudomarginati formed a monophyletic clade, although not supported by high bootstrap value. The clade is further divided into three well-supported clades representing distinct species (Th. balcanus, Th. praecox and Th. moesiacus). In our study, the AFLP markers demonstrated that they could be suitable for studying complex genetic relationships, including frequent interspecies hybridization events, although strict reticulate evolutionary history could not be determined. All the population genetic parameters in the section Serpyllum suggest that the reproductive incompatibility between the species is very weak, which indicates a strong reticulating system, especially in the case when two or more species occur sympatrically.     

Foliage-dwelling ants in a neotropical savanna: effects of plant and insect exudates on ant communities

Ant dominance in tropical ecosystems can be explained by a capacity to exploit liquid foods such as extrafloral nectaries (EFNs) and secretions from honeydew-producing hemipterans (HPHs). Such nutritious exudates may determine ant distribution in space and shape specialization in ant–plant interactions. We provide a first assessment of how EFNs and HPHs mediate the structure of ant assemblages, ant visitation intensity, and characteristics of ant–plant interaction networks across space in Brazilian “cerrado” savanna. We used arboreal pitfall traps to sample visiting ants in four cerrado localities and recorded the presence of lepidopteran larvae to determine their possible response to ant visitation. Ant species composition and richness did not differ regardless of the presence of liquid rewards on plants, and most network patterns did not show consistent differences. However, in two of the four sites, ant densities were higher on plants with HPHs or EFNs due to increased activity by Camponotus and Pseudomyrmex ants. At these two sites, plants with liquid food sources had a more specific ant assemblage (higher specialization d′) than did plants without resources, and caterpillars were more frequently found on plants with fewer workers of Camponotus and Pseudomyrmex. Plants with HPHs had increased ant visitation and accumulated more ant species than did plants with EFNs or without liquid foods. Ant response to such food sources may thus depend on local conditions and identity of ant species, and may determine how ant assemblages are structured. Results highlight how different patterns of ant visitation to liquid resources can produce distinctive effects on herbivore infestation.     

Testing the optimal defense hypothesis in Stryphnodendron adstringens (Fabaceae,Mimosoideae) leaves: the role of structure,number, position and nectar composition of extrafloral nectaries

Stryphnodendron adstringens is a common Cerrado tree that possesses extrafloral nectaries (EFNs) on its leaves, which are located at the base and apex of the rachis and along the secondary veins. The position of EFNs and their nectar production can be affected by defense strategies because plant organs possess different values and herbivory vulnerability. Here we aimed to elucidate anatomy, histochemistry, nectar composition and EFN number on leaves of S. adstringens in the light of the optimal defense hypothesis. We found a convergence on anatomy and histochemical characterization because the three studied types of EFNs have epidermis, secretory parenchyma and vascular tissue, showing phenolic compounds and polysaccharides in the secretory parenchyma cells. The nectar contained glucose, fructose and sucrose, which attract ants of the Camponotus and Cephalotes genus. We found differences in the number of EFNs along the secondary veins and in the nectar composition between EFNs located at the base and apex of the rachis of the leaf. The number of EFNs on the secondary veins increases from the base to the apex, suggesting a strategy to induce ant patrolling over the entire leaf region. EFNs at the base secreted more nectar, which should be related to the protection of the leaf base, which is the part most vulnerable to herbivore attack and the most valued organ. We concluded that EFNs of S. adstringens are anti‐herbivore defenses whose pattern matches the predictions of the optimal defense hypothesis.     

Cladistic and phenetic analyses of relationships among Fusarium spp. in Dongtan wetland by morphology and isozymes

Variations of 12 morphological characters and 78 isozymic bands among 78 isolates of five Fusarium spp. from Dongtan wetland were described and analysed with cladistic parsimony and phenetic UPGMA methods. Hierarchical cluster analysis of 12 morphological characters grouped 78 strains into five defined species with a high overlap between isolates. Hierarchical cluster analysis of isozyme patterns showed a higher degree of relationship among five Fusarium spp., in which Fusarium nivale, Fusarium semitectum and Fusarium oxysporum clustered as one group, and F. semitectum was closer to F. nivale than to F. oxysporum; Fusarium graminearum and Fusarium moniliforme formed one group and showed clearly distinct from the first group. Groups of individual isolates indicated by a plot of principal component analysis were consistent with these findings. The comparison of two different data sets revealed that isozyme patterns showed higher variations between species and among individual isolates than morphological characters. Parsimony analysis of morphological characters yielded unresolved cladograms. Parsimony analysis of isozymes as presence/absence characters revealed the same five species in general as the results indicated by phenetic analysis, differing in the relative position of species in subclusters.     

Species delimitation in the European species of Clavulina (Cantharellales, Basidiomycota) inferred from phylogenetic analyses of ITS region and morphological data

The identification of the conventionally accepted species of Clavulina (Cantharellales, Basidiomycota) in Europe (Clavulina amethystina, Clavulina cinerea, Clavulina cristata, and Clavulina rugosa) is often difficult and many specimens are not straightforwardly assignable to any of those four species, which is why some authors have questioned their identity. In order to assess the status of those species, a morphological examination was combined with the molecular analysis of the ITS region. The same six major clades were obtained in the Bayesian and parsimony phylogenetic analyses, and all six clades were well-supported at least by one of the analyses. Morphological characters, such as the overall branching pattern, the presence and intensity of grey colour, the cristation of the apices, and basidiospore size and shape were to various extents correlated with the phylogenetic signal obtained from the ITS region. The congruence between the molecular analyses and morphology, rather than geographical origin, suggests the existence of several species that can be delimited using a combined phylogenetic and morphological species recognition. The analyses revealed that C. cristata and C. rugosa are well-delimited species. In contrast, more than one taxa could be subsumed under the names C. amethystina and C. cinerea, the taxonomical complexity of which is discussed. The ITS region is proved to be adequate to separate phylogenetic species of Clavulina.     

Ants visiting extrafloral nectaries and pyrrolizidine alkaloids may shape how a specialist herbivore feeds on its host plants

The presence of extrafloral nectaries (EFNs) attracts predators and parasitoids, and protects the plant against herbivorous insects. By improving plant defences, EFNs reduce the fitness of herbivores. The use of similar host plants with no EFNs or adaptations in response to predators and parasitoids may enhance herbivore fitness. In this context, we studied the feeding habit (on leaves or on unripe seeds inside the pods) of larvae of the specialist moth Utetheisa ornatrix in two Crotalaria host plant species in which EFNs are present (C. micans) or absent (C. paulina). We hypothesized that the moths’ feeding habit was influenced by its natural enemies via their presence on EFNs. In C. micans, we found more larvae feeding inside the pods rather than on the leaves, while in C. paulina, larvae were found in both parts of the plant. There was greater activity of natural enemies in C. micans than in C. paulina. The moth sequesters enough pyrrolizidine alkaloid (PAs) to defend against predators in the leaves and seeds of C. paulina, but only in seeds of C. micans. Therefore, a change in the feeding habit in U. ornatrix larvae is a plastic response that depends on whether EFNs are present or not, or whether PA concentrations are low or high. This change does not affect overall moth performance. However, other factors, such as pod hardness, predation by organisms other than those visiting EFNs or even parasitoids cannot be ruled out as being responsible for the change in feeding habit. To date, both the EFNs and PAs in Crotalaria species are a parsimonious explanation of how larvae of U. ornatrix use different species of Crotalaria for feeding.     

Oligocene ferns from the Rancahué Formation (Aluminé, Neuquén, Argentina): Cuyenopteris patagoniensis nov. gen., nov. sp. (Polypodiales: Blechnaceae/Dryopteridaceae) and Alsophilocaulis calveloi Menéndez emend. Vera (Cyatheales: Cyatheaceae)

The study of abundant permineralized fern remains collected in the Oligocene Rancahué Formation (Neuquén Province, Argentina) allowed the identification of two different taxa. The name Cuyenopteris patagoniensis nov. gen., nov. sp. is proposed for several stems and fronds characterized by the presence of caulinar dictyosteles with root gaps, producing C-shaped leaf traces composed by two hippocampiform bundles flanked by eight to ten small round bundles, half of them diverging from cauline meristeles and the rest from the hippocampiform bundles. The presence of these features, along with frond bases with adaxial grooves and a pair of pneumatophores, suggest affinities with the Blechnaceae or Dryopteridaceae. The second identified taxon is Alsophilocaulis calveloi Menéndez. Based on features observed in these new materials, including characteristics of the mantle of adventitious roots and anatomy of the petiole bases, an emended diagnosis for this latter species is proposed.     

Comparative leaf' anatomical studies of some Mallotus Lour. (Euphorbiaceae) species

A comparative study was undertaken on the leaves and petioles of 16 species of Mallotus in order to investigate anatomical variations of potential in species identification. There is a range of characters which varies between species. These include the outline of the midrib and petiole in transverse sections, the shape of the vascular tissue in midribs, the presence of central bundles in the petiole, the presence of terminal sclereids, enlarged tracheids, presence or absence of non-glandular trichomes, and parenchymatous sheaths in vascular bundles. A combination of these characters may be used to identify species. Anatomical data support the placing of only a few species into the respective sections.