Palynological analysis of Dennstaedtiaceae taxa from the Paranaense Phytogeografic Province that produce monolete spores and its systematic implications (I): Blotiella lindeniana , Histiopteris incisa and Paesia glandulosa.

The genera of Dennstaedtiaceae have sporophytes with very different morphological characteristics between each other, and this feature has made difficult the systematic circumscription of the family. This reason makes necessary the study of new characters that allow a better understanding of the relations within the group. The spore morphology and wall structure of Blotiella lindeniana, Histiopteris incisa and Paesia glandulosa from the Paranaense Phytogeographic Province were studied using light microscope, and scanning and transmission electron microscope. The exospore has two layers and, according to the species, the exospore surface bears pila, echinae, verrucae, bacula and tubercles. The perispore has two or three layers and its surface is psilate, baculate or rugulate. The variability found in the sculpture of the spores and their stratification and ultrastructure of perispore reflects the morphological differences observed in the sporophyte of the species studied. Additionally, while the stratification and ultrastructure of the exospore is shared by the Dennstaedtiaceae species, their ornamentation could be a character to distinguish species into the clade "hypolepidoide". The finding of spores with similar characteristics in phylogenetically unrelated families allows us to suggest that palynological features do not have an evolutionary value to establish relationships between groups above the genus level.

Palynological analysis of Dennstaedtiaceae taxa from the Paranaense Phytogeografic Province that produce monolete spores and its systematic implications (I): Blotiella lindeniana, Histiopteris incisa and Paesia glandulosa

ABSTRACT The genera of Dennstaedtiaceae have sporophytes with very different morphological characteristics between each other, and this feature has made difficult the systematic circumscription of the family. This reason makes necessary the study of new characters that allow a better understanding of the relations within the group. The spore morphology and wall structure of Blotiella lindeniana, Histiopteris incisa and Paesia glandulosa from the Paranaense Phytogeographic Province were studied using light microscope, and scanning and transmission electron microscope. The exospore has two layers and, according to the species, the exospore surface bears pila, echinae, verrucae, bacula and tubercles. The perispore has two or three layers and its surface is psilate, baculate or rugulate. The variability found in the sculpture of the spores and their stratification and ultrastructure of perispore reflects the morphological differences observed in the sporophyte of the species studied. Additionally, while the stratification and ultrastructure of the exospore is shared by the Dennstaedtiaceae species, their ornamentation could be a character to distinguish species into the clade "hypolepidoide". The finding of spores with similar characteristics in phylogenetically unrelated families allows us to suggest that palynological features do not have an evolutionary value to establish relationships between groups above the genus level.

Palynological analysis of Dennstaedtiaceae taxa from the Paranaense Phytogeographic Province that produce Trilete spores II: Microlepia speluncae and Pteridium arachnoideum.

The spore morphology and wall ultrastructure of Microlepia speluncae and Pteridium arachnoideum from the Paranaense Province were analyzed with LM, SEM and TEM and a comparative analysis was carried out. In both species the spores are covered by a three-dimensional network of threads branched and fused, tangentially arranged to the surface, and some free-end threads are also seen. The species were differentiated by morphology and the frequency of threads fusion and the networks distribution on the surface of the spores. In both species the exospore is two-layered in section, both layers are traversed by single or branched channels. The perispore is three-layered in section: the inner layer is adhered to the exospore, the middle layer is formed of a three-dimensional network of threads and the outer layer is discontinuous. The perispore ultrastructure of Microlepia speluncae was interpreted as formed of helical subunits displayed around a central channel. The spore morphology and perispore ultrastructure allow differentiating Microlepia from Pteridium but also to the other Dennstaedtiaceae genera that grow in the Paranaense Province. The results obtained allow establishing relationships that let us recognize different groups and gave a new reference to get a better knowledge of the family.

Distribution of Ophioglossum reticulatum L. in South America. A case of long-distance jump dispersal?

The objective of this exploratory work is to test the hypothesis that South American populations of Ophioglossum reticulatum L. derive from Africa. Spores cross the Atlantic transported by wind and arrive in South America in recurrent migration. Three-dimensional (backward and forward) trajectories of spores between Africa and South America were calculated using the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT4). The model showed possible backward trajectories in the low troposphere arriving in South America with probable origin in Northwestern Africa. The results support the hypothesis of long-distance dispersal of the studied species. Including vertical motion in the model runs allowed obtaining valuable and novel information about the migration routes. The trade winds combined with the South American monsoon could be a dispersal vehicle for the disseminules from Northwestern Africa to the eastern slopes of the Andes. As the monsoon is a periodic regional atmospheric circulation pattern, transcontinental migration can be assumed to be a recurring phenomenon that provides genetic exchange and prevents speciation by reproductive isolation. Modelled forward trajectories connect the neotropics with Africa-Madagascar, but they seem to be less effective due to their travelling altitudes. This hypothesis might explain the absence of infraspecific taxa restricted to different geographic locations.

Comparative palynological analysis of Lygodium venustum Sw. and L. volubile Sw. (Lygodiaceae).

The genus Lygodium Sw. is one of the few climbing ferns in the world. The spores of L. venustum Sw. and L. volubile Sw. were studied using light, scanning, and transmission electron microscopy. This work is based on herbarium material. The spores are trilete, triangular, with straight to convex sides in polar view. The equatorial diameter is 72-104 µm, and the polar diameter is 64-84 µm. The ornamentation in L. venustum is verrucate-tuberculate while in L. volubile, it is verrucate-tuberculate in the proximal face but with a few ridges on the distal face, where a micro-ornamentation constituted by verrrucae and tubercles is observed. An equatorial ridge is also present. The exospore is two-layered; in L. venustum, it is smooth in contrast with the ornamented exospore of L. volubile. The perispore of the two species analyzed is similar. This wall is four-layered with particular elements arranged radially in the middle layer. On the spores surface of both species, few spheroids are observed. The results introduced in the current study may be useful for the systematics of the genus as well as for phylogenetic purposes.

Palynological analysis of Sphaeropteris gardneri (Cyatheaceae, Pteridophyta).

The spore morphology and wall ultrastructure of Sphaeropteris gardneri (Hook.) R.M. Tryon from Brazil were analyzed with LM, SEM and TEM. The spores are trilete with an ornamentation formed of short low ridges with spines in their margins. The exospore is 2.5microm thick, two- layered in section and single or branched channels are present. The perispore is 1.2microm thick and two-layered. The inner layer has three strata: the inner stratum is formed of a network of branched and fused threads, the middle stratum has threads with a radial orientation and in the outer stratum thin, dark fibres are immersed in a less dense contrasted matrix. The outer layer of the perispore is the one that forms the echinate-ridges and is constituted of threads arranged in a compact way. Globules of different sizes are observed on the surface. The differences found in the perispore ornamentation and ultrastructure in Alsophila, which was previously studied, and those of Sphaeropteris, show a tendency to wall complexity.

Palynological analysis of Sphaeropteris gardneri (Cyatheaceae, Pteridophyta)

The spore morphology and wall ultrastructure of Sphaeropteris gardneri (Hook.) R.M. Tryon from Brazil were analyzed with LM, SEM and TEM. The spores are trilete with an ornamentation formed of short low ridges with spines in their margins. The exospore is 2.5μm thick, two- layered in section and single or branched channels are present. The perispore is 1.2μm thick and two-layered. The inner layer has three strata: the inner stratum is formed of a network of branched and fused threads, the middle stratum has threads with a radial orientation and in the outer stratum thin, dark fibres are immersed in a less dense contrasted matrix. The outer layer of the perispore is the one that forms the echinate-ridges and is constituted of threads arranged in a compact way. Globules of different sizes are observed on the surface. The differences found in the perispore ornamentation and ultrastructure in Alsophila, which was previously studied, and those of Sphaeropteris, show a tendency to wall complexity.

A morfologia dos esporos e a ultraestrutura da parede de Sphaeropteris gardneri (Hook.) R.M. Tryon, Brasil, foram analisadas com MO, MEV e MET. Os esporos são trilete com uma ornamentação formada por cristas curtas e baixas e com espinhos em suas margens. O exosporo possui 2,5μm de espessura, duas camadas em secção e estão presentes canais simples ou ramificados. A camada interna possui três estratos: o estrato interno é formado por uma rede de filamentos ramificados e fusionados, o estrato médio tem fios com uma orientação radial e no estrato externo fino, fibras escuras estão imersas em uma matrix menos densa. A outra camada do perisporo é a que forma as cristas equinatas e é constituída de filamentos dispostos em um arranjo compacto. Glóbulos de diferentes tamanhos são observados na superfície. As diferenças encontradas na ornamentação do perisporo e na ultraestrutura do Alsophila estudado previamente e aqueles de Sphaeropteris mostram uma tendência à complexidade da parede.

Stages in development of Selaginella diffusa megaspores.

In mature megaspores of Selaginella diffusa (C. Presl) Spring the units of the exospore are ordered and become unordered toward the outer and inner surfaces. The exospore surface is coated with silica at maturity. The insertion of the future gap begins in early stages with formation of many minigaps within the inner part of the exospore distally. The mesospore, like the exospore, is resistant to the acetolysis reaction and can, thus, provisionally be considered to consist of sporopollenin. Unit structures within the outer part of the mesospore are unordered, but become ordered in the middle and inner parts. The inner surface of the mesospore appears verrucate. In maturing megaspores, the mesospore is mostly disintegrated and the inner exospore, which encapsulated the mesospore, remains as a somewhat isolated structure, and is again near the outer exospore. There are connecting strands across the gap between the inner surface of the outer exospore and the surface of the inner exospore. There are also spheres on the outer surface of the inner exospore.