Effect of temperature and dark pretreatment on the germination of three species of Jamesonia (Pteridaceae,Polypodiopsida)

To study the influence of temperature on the germination ability of three species of Jamesonia (Jamesonia imbricata, Jamesonia scammaniae and Jamesonia rotundifolia), spores were cultured at 10°C, 15°C and 20°C. A temperature of 15°C was selected as representative of the natural annual average temperature of the paramo environment that Jamesonia species inhabit. In addition, a dark pretreatment of 2 days was tested to verify if germination was enhanced. The results indicated that germination of Jamesonia, considering the three species as a whole, is affected by temperature, but is independent of the dark treatment. All species showed higher and faster germination at 20°C, and exhibited a threshold minimum temperature around 10°C, below which germination is avoided or extremely low and delayed. This could suggest that spore germination in Jamesonia is adapted to establish gametophyte populations during frost‐free periods.     

Phylogenetics and biogeography of the neotropical fern genera Jamesonia and Eriosorus (Pteridaceae)

Jamesonia and Eriosorus are two traditionally recognized fern genera in the Neotropics that together form a monophyletic group. Molecular phylogenetic analyses for this study suggest, however, that neither genus is itself monophyletic and that several independent lineages with the jamesonia morphotype have each undergone a fairly recent radiation in páramo ecosystems. A robust phylogeny was generated based on sequence data of the nuclear external transcribed spacer (ETS) of 18S-26S rDNA, the plastid gene rps4 and the intergenic spacer rps4-trnS. Several conclusions can be made concerning the evolutionary history and biogeographic patterns of the Jamesonia-Eriosorus complex: (1) "jamesonia" is polyphyletic, making "eriosorus" paraphyletic; (2) all analyses recover three major clades in the Andes; (3) two well-supported clades can be recognized, corresponding to the northern vs. central Andes; and (4) the sister taxon of the Andean radiation is the Brazilian taxon Eriosorus myriophyllus. Jamesonia is a potential example of a recent adaptive radiation because the group is characterized as being morphologically and ecologically diverse and its habitat is of recent origin.     

Spore morphology and wall ultrastructure of Trachypteris species (Pteridaceae)

Trachypteris is a small genus consisting of four species native to America and Madagascar: Trachypteris induta, T.?pinnata, T.?gilliana, and T.?drakeana. The spores of the genus were studied using light microscopy and scanning and transmission electron microscopy. They are trilete, triangular to globose, with equatorial diameter of 29?C58???m and polar diameter of 26?C53???m. The exospore is 0.5?C1.1???m thick, plane, and two-layered. The perispore is 0.3?C6.8???m thick and two-layered. Depending on the species, two different ornamentations were observed: cristated with partially fused cristae, and ridged with partially fused ridges, forming an incomplete reticulum. Globules immersed in the perispore were occasionally observed. The systematic value of the Trachypteris spores is discussed, and their morphology and ultrastructure are compared with those of other related cheilanthoid ferns. The palynological characteristics presented here may be useful for phylogenetic studies within the Pteridaceae, and particularly within the cheilanthoid ferns.     

Ovule morphology, embryogenesis and seed development in three Hylocereus species (Cactaceae)

Pre-embryonic and embryonic stages and seed developments were studied in the diploids Hylocereus monacanthus and Hylocereus undatus and the tetraploid Hylocereus megalanthus. Ovule morphology was similar among species except for micropyle entrance. H. monacanthus had the thickest and most robust suspensor. Embryo developmental time, measured from fertilization to maturity, was significantly more prolonged in H. megalanthus. Typical to Cactaceae, the seed coat was formed by one layer of sclerenchymatous cells, but was more lignified in H. megalanthus. Morphological features common to all species included (1) cellular type endosperm with independent patterns of development in the chalazal and micropylar zones, forming a haustorium layer from the chalazal zone to the embryo; (2) an endothelial layer surrounding the embryo sac almost complete; (3) a nucellar summit growing into the micropyle; and (4) a placental obturator and a funicle connecting the ovarian tissue to the ovule. Seed development was typically endospermic (exendospermic orthodox seeds). Anomalies included two egg cells in the same embryo sac, two embryos developing in the same ovule, and embryos developing from the chalazal pole region. Total seed number and seed viability were significantly lower in H. megalanthus than in the other two taxa. Embryos at different developmental stages were observed in aborted H. megalanthus seeds.     

New species of ferns (Polypodiopsida) from Ecuador

The following new species of ferns are described and illustrated: Arachniodes squamulosa, Cyathea halonata, C. punctata, Polypodium fayorum , and Trichomanes paucisorum.     

The occurrence and morphology of Adiantum X variopinnatum (Pteridaceae)

Two populations ofAdiantum Xvariopinnatum were found at the La Selva Biological Field Station in Costa Rica. The plants were morphologically intermediate between their parents, showed additive isozyme banding patterns, and had aborted spores. Herbarium searches for the hybrid turned up specimens from Nicaragua, Costa Rica, Panama, Venezuela, and Colombia. These are the first reports of the hybrid outside of Trinidad.     

Palynology of South American Argyrochosma and Notholaena (Pteridaceae) species

The palynology of the South American taxa Argyrochosma chilensis (J. Rémy) Windham, A. nivea (Poir.) Windham, var. nivea , var. flava (Hook.) Ponce, var. tenera (Hook. ex Gillies) Ponce and A. stuebeliana (Hieron.) Windham; N. sulphurea (Cav.) J. Sm. and N. galapagensis Weath. & Svenson has been investigated. These species show differences in spore size, shape, sporoderm thickness and structure. In both genera, the exospore is psilate and the perispore has either cristate-reticulated or reticulated ornamentation, with a complex structure and stratification. The perispore presents several characteristics useful in establishing differences valuable for taxonomic purposes. The investigated species of Argyrochosma have a perispore with a middle stratum composed of radial rodlets, and an outer continuous stratum, which bears the elements of the sculpture. These are independent of the inner structure. The spores of the investigated Notholaena species have a thick, complex, three-stratified perispore, with an outer discontinuous stratum. The middle stratum is composed of threads ramified at several levels and laterally fused. The elements of the sculpture show continuity with those of the structure. Granular material of sporopolleninous composition fills the lumina at the surface. Abnormal spores and 32 spores per sporangium were frequent in specimens of A. nivea var. nivea and N. sulphurea .     

A new species of Adiantum (Pteridaceae) from Bahia, Brazil

A new species,Adiantum discolor Prado (Pteridaceae), known only from the wet forests of eastern coastal Brazil, in Bahia, is described and illustrated. It is distinguished principally by its 2-pinnate fronds with a long stipe, 2 or 3 pairs of lateral pinnae, discolorous laminae, and glabrous indusia. Uma nova espécie,Adiantum discolor Prado (Pteridaceae), conhecida somente das florestas úmidas da costa leste do Brasil, no Estado da Bahia, é descrita e ilustrada. Distingüe-se princi-palmente pelas frondes 2-pinadas com um longo pecíolo, 2 ou 3 pares de pinas laterais, laminas discolores e indúsios glabros.     

Six new species of ferns (Polypodiopsida) from Ecuador

Moran, R.C. & Øllgaard, B. 1995. Six new species of ferns (Polypodiopsida) from Ecuador. - Nord. J. Bot. 15: 177–185. Copenhagen. ISSN 0107–055X.
The following species of ferns from Ecuador are described as new: Blechnum mono-morphum. Bolbitis riparia, Hecistopteris pinnatifida, Hymenophyllum hemidimorphum, Polypodium latissimum , and Saccoloma laxum .     

New species in Adiantum and Pteris (Pteridaceae) from the Andes

We describe, discuss, and illustrate four new species, one inAdiantum (A. capillatum A. R. Sm. &; Prado, from Ecuador) and three species inPteris (P. lellingeri A. R. Sm. &; Prado, from Bolivia;P. venezuelensis A. R. Sm. &; Prado, from Venezuela; andP. websteri A. R. Sm. &; Prado, from Ecuador, Colombia, and Bolivia).     

Comparative morphology and development of bony elements in the head region in three species of Japanese catfishes (Silurus: Siluridae; Siluriformes)

The shape and development of bony elements of the neurocranium and suspensorium were studied in three species of Japanese catfish (Silurus) from the viewpoint of comparative morphology. InS. asotus andS. biwaensis the order of appearance of the bony elements was similar, but the ossification of most elements was delayed inS. lithophilus. The neurocranium and Suspensorium of adultS. lithophilus retain juvenile features compared with the other two species. On the other hand, in the skull ofS. biwaensis the sagittal crest of the supraoccipital, the ridge of the pterotic, and the hyomandibular process are more developed than in the other two species.     

Comparative cytogenetics of three species of Dichotomius (Coleoptera, Scarabaeidae)

Meiotic and mitotic chromosomes of Dichotomius nisus, D. semisquamosus and D. sericeus were analyzed after conventional staining, C-banding and silver nitrate staining. In addition, Dichotomius nisus and D. semisquamosus chromosomes were also analyzed after fluorescent in situ hybridization (FISH) with an rDNA probe. The species analyzed had an asymmetrical karyotype with 2n = 18 and meta-submetacentric chromosomes. The sex determination mechanism was of the Xy(p) type in D. nisus and D. semisquamosus and of the Xy (r) type in D. sericeus. C-banding revealed the presence of pericentromeric blocks of constitutive heterochromatin (CH) in all the chromosomes of the three species. After silver staining, the nucleolar organizer regions (NORs) were located in autosomes of D. semisquamosus and D. sericeus and in the sexual bivalent of D. nisus. FISH with an rDNA probe confirmed NORs location in D. semisquamosus and in D. nisus. Our results suggest that chromosome inversions and fusions occurred during the evolution of the group.     

Sperm morphology,spermatogenesis and spermiogenesis of three species of chitons (Mollusca,Polyplacophora)

Summary Mature sperm of the three species, Onithochiton quercinus, Chiton pelliserpentis and Plaxiphora paeteliana are eupyrene and basically of the primitive type. The sperm are small, with a distinct head, midpiece with a few spherical to oval mitochondria and a long tail with a (2×9)+2 axoneme. They are unusual among primitive sperm in being bilaterally symmetrical, with a long anterior filament containing an extension of the nucleus and lacking an acrosome. Spermatogenesis occurs synchronously throughout the testis in inwardly folded tissue plates. Spermatogonia arise adjacent to the central blood sinus in each tissue plate. Cells in successive stages of spermatogenesis are displaced towards the luminal surface. The cytoplasm of all stages contains ribosomes, rough endoplasmic reticulum, lysosomes and mitochondria. A Golgi complex is present in secondary spermatocytes and spermatids but does not form an acrosome. During spermiogenesis Golgi complexes are confined to the posterior region of developing sperm and are eventually shed in the residual cytoplasm behind the midpiece. Preacrosomal vesicles are not formed. The long anterior filament of the sperm and lack of an acrosome are features associated with the fertilization of eggs surrounded by a chorion which may have pores or a micropyle. The exact method of fertilization in chitons remains to be elucidated.Abbreviations af anterior filament - bh body of the head - bn body of the nucleus - bs blood sinus - c collar - dc distal centriole - esg early spermatogonium - fc fibrous chromatin - gc granular chromatin - if implantation fossa - lsg later spermatogonium - m mitochondrion - mc muscle cell in blood sinus - mm midpiece mitochondrion - mt microtubule - mI primary spermatocyte undergoing first meiotic division - mII secondary spermatocyte undergoing second meiotic division - n nucleus - ncc nuclear condensing chromatin - ne nuclear envelope - pc proximal centriole - rc resorbing cell - s spermatozoon - 1°sc primary spermatocyte - 2°sc secondary spermatocyte - st spermatid - t tail - tc thinning cytoplasm - tf tail flagellum - tpec tissue plate epithelial cell     

Five new species and two new combinations of ferns (Polypodiopsida) from Ecuador

Five new species of ferns are described: Alsophila esmeraldensis, Blechnum rheophyt-icum, Cyathea amazonica, C. hemiepiphytica , and C. palaciosii . Two new combinations are made: Cyathea bipinnata and Pecluma pastazensis .     

Comparative morphology of three South African Triviidae (Gastropoda: Prosobranchia) with the description of a new species

Three species of Trivia were collected from subtidal habitats in the Cape of Good Hope Peninsula, South Africa. The morphology of T. ovulata (Lamarck, 1811), T. millardi (Cate, 1979) and T. verhoefi sp. nov. is described. Each species can be distinguished by a unique pattern of mande coloration, conchological characters of the fossula and shape of the radular teeth. The central nervous system was examined and found to be of the same configuration in die diree South African spe Trivia ovulata and T. verhoefi appear to be gonochoric while T. millardi is a protandric hermaphrodite. Trivia ovulata and T. millardi also differ in the position of the receptaculum seminis. Differences in internal morphology reported in previous work and the present study are discussed. The fact that the central nervous system of Trivia is euthyneurous is reconfirmed. Trivia ovulata and T. millardi were associated with colonial tunicates as previously recorded for other members of the genus.     

Three new species of Adiantum (Pteridaceae) from Bolivia and Peru

Three new species from Bolivia and Peru (Adiantum solomonii, A. tryonii, andA. tuomistoanum) are described and illustrated.     

Two new species and new records for Pteris (Pteridaceae) from Colombia

A systematic review of the Colombian species of the tribe Pterideae (Pteridaceae) resulted in the discovery of two new species ofPteris:P. muricatopedata andP. albertiae, both in the Deflexa group. Two species are reported for the first time from Colombia:P. bakeri C. Chr. andP. lechleri Mett.     

Ultrastructure of sperm development and mature sperm morphology in three species of commensal bivalves (Mollusca: Galeommatoidea)

Ultrastructural features of the ovotestes, spermatogenesis, and the mature sperm are described for three galeommatid bivalves, Divariscintilla yoyo, Divariscintilla troglodytes, and Scintilla sp., from stomatopod burrows in eastern Florida. All three species yielded similar results except with respect to mature sperm dimensions. The ovotestis contains three types of somatic cells within the testicular portion: flattened myoepithelial cells defining the outer acinal wall; underlying pleomorphic follicle cells containing abundant glycogen deposits; and scattered, amoeboid cells containing lysosomal-like inclusions which are closely associated with developing sperm. Early spermatogenesis is typical of that reported from other bivalves. In contrast, the late stages of spermiogenesis involve the migration and gradual rotation of the acrosomal vesicle, resulting in a mature acrosome tilted about 70° from the long axis of the cell. The mature sperm possesses an elongated, slightly curved nucleus; a subterminal, concave acrosome with a nipple-like central projection; five spherical mitochondria and two centnoles in the middlepiece; and a long flagellum. The rotational asymmetry and the presence of perimitochondrial glycogen deposits in these sperm are unusual in the Bivalvia and may be associated with fertilization specializations and larval brooding common among galeommatoideans.