Edmund Fredric Warburg; 1908–1966

Abstract

Ultrastructural analyses of mid-stage spermatids of Hypnum jutlandicum and H. mammillatum reveal a maximally structured blepharoplast closely similar in most respects to the other moss taxa previously investigated. The multilayered structure is four-layered and the dimorphic basal bodies highy staggered. The latter are inserted into the gamete in a slightly staggered subapical position. Both are longer than those reported for the majority of mosses and hepatics. Like other true mosses, the posterior basal body diverges from the longitudinal axis of the spermatid and is associated with a solitary microtubule which is equally divergent from the main body of the spline. In contrast to previous reports on other mosses, the stray microtubule of Hypnum is here interpreted as remaining separate from the spline, i.e., it does not converge posteriorly with the body of the spline.

The lamellar strip of Hypnum is roughly oblong in outline with an acute anterior tip which extends beyond the spline microtubules both anteriorly and on the righthand side. The posterior margin of the lamellar strip rapidly tapers from right to left. Like most mosses, the lamellar strip is approximately the same length as the anterior basal body and terminates at the level of the anterior basal body transition zone. In hepatics, in contrast, the lamellar strip subtends the posterior basal body over most of its length.     

COMPARATIVE ULTRASTRUCTURAL STUDIES OF SPERMATOGENESIS IN THE METZGERIALES (HEPATICAE). I. THE BLEPHAROPLAST OF PALLAVICINIA LYELLII

The blepharoplast in the young spermatid of Pallavicinia is similar to that of other hepatics in that it comprises a four-layered multilayered structure (MLS) and two staggered, dimorphic basal bodies. The spline, approximately 40 μm in length and extending through nearly two full gyres, comprises 20 parallel microtubules at its anterior end and narrows to 17 at the posterior limit of the subjacent lamellar strip (LS). Behind this, the spline shank, approximately 32 μm in length, is reduced to six tubules. The LS curves around the spermatid, following the anterior one-third of the first gyre of the spine, and is approximately 7.5 μm in length, the longest yet recorded for the bryophytes. It is spatulate in outline, equaling the width of the spline anteriorly but tapering steeply from the right-hand side behind the anterior basal body (ABB). It then extends posteriorly as a narrow strip beneath the left-hand margin of the spline. The basal bodies of the greatly staggered flagella are nonoverlapping and separated by a distance of about 4.4 μm. The subapical ABB and PBB measure (including the ventral triplet extensions and transition zones) 1.2 μm and 2.4 μm in length, respectively. A short, narrow aperture equaling one tubule-diameter in width is located in the spline directly beneath the ABB. The anterior mitochondrion is about 7 μm long and follows the outline of the overlying LS, while a cupshaped posterior mitochondrion is appressed to the plastid. Comparisons with other taxa indicate that major distinguishing features of metzgerialian blepharoplasts are highly staggered, nonoverlapping basal bodies, greatly elongate anterior mitochondria, and six-tubule shanks. Great differences between the spermatids suggest wide phylogenetic discontinuities between the genera of the Metzgeriales.     

COMPARATIVE ULTRASTRUCTURAL STUDIES OF SPERMATOGENESIS IN THE METZGERIALES (HEPATOPHYTA) II. THE BLEPHAROPLAST OF BLASIA PUSILLA

As in other hepatics, the young spermatid of Blasia pusilla contains a well-developed blepharoplast comprising a four-layered multilayered structure (MLS) and two overlying dimorphic basal bodies. The asymmetrical spline (S₁ or upper stratum of the MLS) numbers 20 or 21 microtubules (MTs) at its anterior tip and reduces to eight at the posterior limit of the lamellar strip (LS). Behind this the shank of the spline is five or six tubules in width over most of its length, approximately one revolution of the circumference of the gamete. The three-microtubule spline aperture underlies the anterior basal body and like those of most hepatics, it is closed at its anterior end. The asymmetrical LS (approx. 2.0 μm in length) is characterized by a right-hand posterior notch which lies below the spline aperture at the region of the cartwheel configuration of the anterior basal body (ABB). The staggered dimorphic basal bodies overlap for approximately one third of their lengths. Both lie parallel to the long axis of the spline. As in other hepatics, the ABB (1.2 μm in length) is subapical and comprises an anterior hub extension with progressive rearward additions of lateral, dorsal and ventral triplets. Over most of its length (2.1 μm) the longer posterior basal body (PBB) consists of a distinct central hub and three ventral triplets. Transition zones of both basal bodies contain stellate configurations into which the two central axonemal MTs frequently extend. The blepharoplast of Blasia shows several features in common with leafy, simple thalloid and complex thalloid liverworts. Compared with the few Metzgeriales observed thus far, the LS is less elongate and the basal bodies less staggered. Dimensions of basal body components and spline dimensions, however, are comparable to those of most leafy and thalloid hepatics. Striking similarities with the complex thalloid liverworts include a posterior notch in the LS and a spline aperture three MTs wide.     

Some ultrastructural aspects of spermatogenesis inLycopodium complanatum

Summary Analysis of thin sections shows that the blepharoplast in an early spermatid ofLycopodium consists of two basal bodies and the subtending spline apparatus. The latter has a 4-layered or Vierergruppe organization much like that reported for certain bryophytes and vascular plants. During the course of spermatid maturation the vertically lamellate S₂ stratum of the spline apparatus is transformed into a thinner layer of dense osmiophilic material, although the vertical lamellae of the S_3,4 strata persist. Rarely there occurred double Vierergruppen, presumably anomalous structures in which a single layer of spline microtubules is flanked on each side by two separate sets of S_2–4 strata. Longitudinal sections show that the basal bodies in an early spermatid lie parallel and close together with their microtubular triplets imbricating in the same direction. In late spermatids these basal bodies lie antiparallel and widely separated, their triplets now imbricating in opposite directions. This change is intrepreted to result from the relocation of one of the basal bodies to a position halfway around the cell by moving distal end first over the subtending spline. The basal bodies become invested by a globular-textured material not previously observed in plant spermatids. The role of this investing material is tentatively thought to be related to anchorage of the basal bodies.     

MULTILAYERED STRUCTURES (MLSs) IN TWO DINOFLAGELLATES,KATODINIUM CAMPYLOPS AND WOLOSZYNSKIA PASCHERI1

The multilayered structure (MLS), best-known from the flagellar apparatus of charophycean green algae and land plant motile cells, is reported for the first time in members of the Dinophyceae. The MLSs in two dinoflagellates, Katodinium campylops (Harris) Fott and Woloszynskia pascheri (Suchlandt) von Stosch, are similar to other MLSs in possessing the microtubular spline and lamellar strip. Also, as in the majority of MLS-containing organisms, 1) the MLS of each dinoflagellate is closely associated with basal bodies; 2) the spline microtubules possess “keel-like” extensions and 3) extend beyond the MLS, forming a microtubular rootlet that runs beneath the cell surface in a posterior direction; and 4) a mitochondrion is associated with the MLS (K. campylops only) The size, location, and general construction of the MLSs of K. campylops and W. pascheri suggest that they may be homologous to previously described MLSs.     

A contribution to the knowledge of epiphyllous bryophytes of Bioko Island (Equatorial Guinea), including additional remarks on non-epiphyllous species

Abstract

A collection of epiphyllous bryophytes from Bioko Island was investigated. It contained 57 epiphyllous bryophytes, comprising 55 hepatics and two mosses. Three taxa, Cololejeunea eustacei Pócs, Colura calderae Pócs and Lejeunea halei Robinson subsp. africana Pócs, are new to science. Cololejeunea papilliloba Steph. is new to Africa, five species of hepatics are new to West Africa, and an additional 31 species of hepatics are newly reported from Bioko Island. The second part of the paper deals with records of non-epiphyllous collections. Fourteen species are reported for the first time for Bioko Island. Actinodontium dusenii Broth. is made a synonym of Actinodontium streptopogoneum Broth. The following new combination is proposed: Wijkia rigidicaule (Müll.Hal. ex Broth.) Frank Müll., comb. nov. (Basionym: Acanthocladium rigidicaule Müll.Hal. ex Broth.).     

Biodiversity within urban areas: A case study on bryophytes of the city of Cologne (NRW,Germany)

In this study, the urban bryophyte flora of the city of Cologne (W. Germany) was studied. A total of 143 bryophyte taxa (17 hepatics and 126 mosses) were recorded within the metropolitan area of Cologne. Three species were newly recorded for North Rhine‐Westphalia: Hannediella heimii, Schistidium helveticum and Tortula schimperi. Thirteen species red‐listed in NRW were recorded, among them hardly endangered: Bryum intermedium and Syntrichia laevipila and extinction endangered: Syntrichia papillosa. The temperate biogeographic element prevails among Cologne bryophytes. According to frequency of recordance, only 11 species are widespread over the urban area of which three are hepatics.     

Bryocentria (Hypocreales), a new genus of bryophilous Ascomycetes

Bryocentria is described as a new genus of Hypocreales. It is characterized by small orange-coloured perithecia, excipular cells with cyanophilic pitted walls, apical paraphyses, numerous thin-walled asci, small, two-celled ascospores with a cyanophilic central part and parasitism on bryophytes. The generitype B. brongniartii is a frequent biotrophic and host-specific leaf perforator of Frullania dilatata. The related, necrotrophic B. metzgeriae also perforates the leaves of predominantly foliose hepatics. Bryocentria cyanodesma grows necrotrophically and forms superficial ascomata on various mosses. Whereas these three species are known only from Europe, a fourth species from Costa Rica, which causes necrotic lesions in epiphyllous hepatics, is mentioned but not formally described.     

The occurrence of a multilayered structure in the sperm of a pteridophyte

Summary A multilayered structure, previously recorded only in bryophytes, is reported in spermatids of three species of Equisetum. It is interpreted as comprising four layers, recalling the Vierergruppe of Marchantia spermatids. Unlike the multilayered structure of bryophyte spermatids, a rather compact organelle, that of Equisetum forms a thin strip extending almost the whole diameter of the cell. As in bryophytes the upper layer of the Equisetum multilayered structure is composed of parallel microtubules, extending far beyond the underlying layers. The microtubular band is considered equivalent to the similar structure seen in a variety of plant spermatozoids, but in Equisetum it is much longer and composed of many more microtubules than reported from any other plant spermatozoid. The morphology of the multilayered structure is related to the large size and short, broad form of Equisetum spermatozoids.     

Sporophytes of Rhodobryum laxe-limbatum (Ochi) Iwats. et Kop.

Abstract

A check-list of the bryophyte species of the Grand-Duchy of Luxembourg is given and briefly discussed. An appendix deals with infraspecific taxa. The total number of species is 517 (122 hepatics and 395 mosses); taking into account some acceptable infraspecific taxa, this small country has at least 538 different bryophytes.     

Ultrastructural studies of spermatogenesis inAnthocerotophyta V. Nuclear metamorphosis and the posterior mitochondrion ofNotothylas orbicularis andPhaeoceros laevis

Summary Ultrastructural observations reveal that the spermatozoids of the hornwortsNotothylas andPhaeoceros contain two mitochondria and not one as described previously. Mitochondrial ontogeny and nuclear metamorphosis during spermiogenesis in these plants differ from all other archegoniates. The discovery that the posterior region of the coiled nucleus (when viewed from the anterior aspect) lies to the left of the anterior, in striking contrast to the dextral coiling of the nucleus of spermatozoids of other embryophytes, underlines the isolated nature of the hornworts among land plants. As the blepharoplast develops, the numerous ovoid mitochondria initially present in the nascent spermatid fuse to form a single elongated organelle which is positioned subjacent to the MLS and extends down between the nucleus and plastid. At the onset of nuclear metamorphosis, the solitary mitochondrion has separated into a larger anterior mitochondrion (AM) associated with the MLS and a much smaller posterior mitochondrion (PM) adjacent to the plastid. The PM retains its association with the plastid and both organelles migrate around the periphery of the cell as the spline MTs elongate. By contrast, in moss spermatids, where mitochondria undergo similar fusion and division, the AM is approximately the same size as the PM and the latter is never associated with the spline. As in other archegoniates, except mosses, spline elongation precedes nuclear metamorphosis in hornworts. Irregular strands of condensed chromatin compact basipetally to produce an elongated cylindrical nucleus which is narrower in its mid-region. During this process excess nucleoplasm moves rearward. It eventually overarches the inner surface of the plastid and entirely covers the PM.Abbreviations ABB anterior basal body - AM anterior mitochondrion - LS lamellar strip - MLS multilayered structure - MT microtubule - PBB posterior basal body - PM posterior mitochondrion     

SPERMATOGENESIS IN COLEOCHAETE PULVINATA (CHAROPHYCEAE): SPERM MATURATION1

Ultrastructural study showed that the sequence of developmental events occurring during spermatozoid maturation in Coleochaete pulvinata Braun was similar in a number of respects to sperm development in the Charales and lower land plants. Elaboration of cytoskeletal components and associated flagellar basal bodies occurs early, and is followed by an extensive decrease in cytoplasmic volume and increases in densities of cytoplasm and nucleoplasm. Volume decrease and density increases appear to result from exocytosis involving dictyosome vesicles and perhaps endoplasmic reticulum. Elongation of flagella is accompanied by deposition of flagellar and body scales as in the Charales. During final stages of sperm maturation, the MLS undergoes changes in organization of the lamellar strip, which may also occur in archegoniates. In mature sperm of C. pulvinata the MLS and basal bodies are so occluded by dense material that determination of absolute orientation (configuration) is difficult. Thus, absolute orientation of the flagellar apparatus was determined by study of mid-stage spermatids, and found to be the same as previously described by Sluiman for zoospores of C. pulvinata. Finally, it is proposed that the large complex, striated fiber which connects basal bodies in C. pulvinata has been evolutionarily reduced in the Charales and Phaeoceros sp., ultimately disappearing from most embryophytic lines of descent.     

British Bryological Society Expedition to Mulanje Mountain,Malawi 2. Checklist of Malawi bryophytes

Abstract

A checklist of all bryophytes identified from Malawi at May 1991 is presented, with synonyms and references. The list is derived from literature and unpublished collections, and contains 197 mosses and 106 hepatics. The checklist was produced to provide a basis for describing plants new to Malawi, particularly for the British Bryological Society Expedition to Mulanje Mountain, Malawi in 1991. Distribution information is included, and the species accounts include published references and collection numbers where known. All information is held on a computer database.     

How to rely on the unreliable: Examples from Mesozoic bryophytes of Transbaikalia

Three new fossil bryophytes are described from Jurassic and Lower Cretaceous deposits of the Transbaikalia region of Russia. The complex thalloid hepatic Khasurtythallus monosolenioides gen. et sp. nov. belongs to the Marchantiidae, but its combination of characters precludes unequivocal placement in any of the five orders of this subclass, representing most likely an extinct lineage. Paleaethallus squarrosus gen. et sp. nov. is a thalloid plant with scales similar to those of complex thalloid hepatics, although their arrangement and the overall plant structure has little in common with any extant hepatics. Dispersed moss capsules, three of which have attached calyptrae, are described as a form genus Kulindobryum gen. nov. Despite incomplete preservation, some rare characters indicate possible relationship to the genus Tayloria of the Splachnaceae, an extant family of mosses adapted to grow on animal dung, dead bodies and bones. Notably, Kulindobryum co‐occurs with bones of the small feathered dinosaurs Kulindadromeus, which also supports an affiliation of Kulindobryum with the Splachnaceae. The most common and best known Mesozoic moss for the region, the genus Bryokhutuliinia, is appraised for its systematic position and probable affinities with the Dicranales. A scoring approach is introduced for the comparative method of taxonomic placement of fossils with partial suites of morphological characters at the family or order level.     

Evidence for the most basal split in land plants dividing bryophyte and tracheophyte lineages

The problem of relationships among the major basal living groups of land plants is long standing, yet the uncertainty as to the phylogenetic affinity of these lines persists in the literature. Molecular and modern cladistic studies of the phylogenetic relationships of the above groups resulted in a large number of conflicting topologies. However, with the exception of the cladistic analyses of spermatogenesis, suggesting monophyly of extant bryophytes, these studies agree the paraphyletic bryophyte grade is basal within the embryophyte tree. Here we would like to present analyses on the basis of the concatenated datasets of nucleotide and amino-acid sequences of 57 protein-coding genes common to 17 chloroplast genomes of land plants and a charophyte alga Chaetosphaeridium globosum. Character-wise, these are the largest datasets currently available to address the problem of basal relationships within embryophytes. Main lineages of bryophytes, i.e liverworts, hornworts and mosses are represented in our alignments with a single taxon, whereas 14 taxa represent the tracheophytes. With our data, phylogeny with liverwort basal appears to be and artifact related to high and unequal A+T contents among the sequences analysed. Reducing this compositional bias and applying methods developed to counter it, we recovered an alternative, strongly supported topology wherein both bryophytes and tracheophytes are monophyletic. Within bryophytes, hornworts are basal and liverworts are sister to mosses.     

SPERMATOGENESIS IN COLEOCHAETE PULVINATA (CHAROPHYCEAE): EARLY BLEPHAROPLAST DEVELOPMENT

Transmission electron microscopy of serial thin sections was used to reconstruct several early developmental stages of the blepharoplast in Coleochaete pulvinata spermatids. These were compared to published studies of blepharoplast development in Charales and the closest relatives of charophycean green algae among embryophytes, i.e., hornworts and liverworts. Bicentriolar centrosomes such as occur in bryophytes and fern allies were not observed in Coleochaete. Centriole replication in C. pulvinata was orthogonal as in Charales. The resulting two daughter centrioles were oriented perpendicularly and joined proximally by electron-dense material. Their orthogonal relationship was maintained throughout blepharoplast development by a massive, banded connective which appeared early. In spermatids of hornworts and liverworts, a multilayered structure (MLS) develops in association with two centrioles destined to become flagellar basal bodies. When the MLS of these lower land plants is sectioned at right angles to the long axis of the microtubular layer, the MLS is observed to lie beneath cross sections of both centrioles. In contrast, when developing MLSs of C. pulvinata and Charales are similarly sectioned, they occur beside a cross section of just one of the two centrioles. In C. pulvinata (as in other charophytes), MLS lamellae are oriented at a 90-degree angle to the long axis of the S₁ microtubules from the beginning. This contrasts with the 40–45 degree angle between the MLS lamellae and S₁ microtubules universally reported for archegoniates. In early C. pulvinata spermatids, spline microtubules are closely associated with an anterior mitochondrion having a low stromal density and few cristae. An anterior mitochondrion is typically associated with blepharoplast development in hornworts and liverworts, but has not previously been reported to occur in Coleochaete or any other charophycean alga. In Coleochaete, as in hornworts and liverworts, but unlike Charales, structure of mature blepharoplasts reflects early blepharoplast ontogeny. Very little change in positional relationships among blepharoplast components (flagella, connective, MLS) occurs during development. These character-state differences are of importance in cladistic analyses of charophycean algae and lower land plants.     

Flora briológica de la Sierra de Peña Sagra (Cantabria,España)

A list of 244 bryophytes (67 hepatics and 177 mosses) from Sierra de Peña Sagra (Cantabria) is given; Ctenidium molluscum var. sylvaticum is new record from the Iberian Peninsula and 27 taxa are new records for this province. We remark the presence of Cephaloziella hampeana, Lejeunea lamacerina, Kurzia pauciflora, Sphagnum brevifolium, S. girgensohnii, Hypnum hamulosum, Orthotrichum consimile, Ulota bruchii, Mnium lycopodioides, Plagiomnium medium subsp. medium, Grimmia anomala and Tortella densa.     

Ultrastructure of the spermatozoid of Lycopodium obscurum (Lycopodiaceae)

Ultrastructural observations reveal that the spermatozoid of Lycopodium obscurum is crescent shaped and contains two posteriorly directed flagella that are inserted at the front of the cell. The nucleus is broad and elongated with a narrow posterior projection or nuclear diverticulum. Spline microtubules (MTs) number 180 at their maximum and provide the framework for the cell. These MTs extend from the anterior of the locomotory apparatus and along the outermost surface of the nucleus, with a central shank of 14–17 MTs encircling the cell for at least one-third gyre beyond the nucleus. The two basal bodies are slightly staggered and positioned at the front of the cell over a highly elongated multilayered structure (MLS). The MLS extends laterally around the cell anterior and curves posteriorly over the nucleus. One large anterior mitochondrion is situated subjacent to the MLS, while numerous small mitochondria are scattered near or among the lobes of the single plastid. The plastid rests on the inner nuclear surface and contains numerous large starch grains. This cell differs from that of L. cernuum, the only other species of Lycopodium examined to date, in that it is more elongated and has an anterior-posterior orientation of the nucleus, basal bodies, MLS, and spline. Comparisons with coiled gametes of bryophytes and Selaginella suggest that some degree of coiling and cell streamlining may be ancestral in archegoniate spermatozoids.     

A molecular phylogeny of bryophytes based on nucleotide sequences of the mitochondrialnad5 gene

In contrast to animals, the slowly evolving mitochondrial nucleotide sequences of plants appear well suited to investigate phylogenetic relations between old taxonomic groups. Analysis ofnad5 gene sequences in 47 bryophytes, the living representatives of very early land plants, confirm this assessment. Statistically reliable phylogenetic trees are obtained with different mathematical approaches. A group I intron sequence conserved in thenad5 gene of all 30 mosses and 15 liverworts investigated supports a sister group relationship of the two classes. The intron sequence adds phylogenetic information for fine resolution on top of the conserved exon sequences down to the level of classically defined orders or families, respectively. This intron is not present in the hornwortsAnthoceros husnotii andA. punctatus. The results allow statements on diverging taxonomic interpretations and support the monophyly of the liverworts, mosses, Jungermanniidae, Marchantiidae and Bryidae, and allow recognition of subclasses like Hypnanae and Dicrananae. Among the mosses, the derived orders (subclass Bryidae) are confidently set apart from the Sphagnales, Andreaeales, Polytrichales and Tetraphidales with Buxbaumiales occupying a mediating position. Among the liverworts, full support is found for the classic separation of simple (jungermanniid) and complex thalloid (marchantiid) species with a strikingly low mitochondrial sequence divergence among the latter.     

Bryophytes and lichens in 16th-century herbaria

The diversity of bryophyte and lichen collections in 9 of the oldest preserved herbaria (dating from ca 1542 to 1577) was compared, including the first reports of bryophytes and lichens from the ‘En Tibi’ herbarium (possibly 1542–1544) and the herbarium of Leonhard Rauwolf (1560–1563). Bryophytes and lichens formed only a minority in each herbarium compared to the numbers of vascular plant specimens; numbers ranged from representatives of 21 genera in the herbarium of Ulisse Aldrovandi to the single genus Conocephalum in the Rauwolf herbarium. The focus was on large, handsome species of bryophytes and macrolichens, apart from small amounts of additional species collected as ‘by-catch’ in mixed collections. All herbaria together included 34 genera of bryophytes (36 species and 10 specimens identified to genus level) and 13 genera of lichens (24 species and 4 specimens identified to genus level). The diversity of mosses was higher than that of liverworts, and pleurocarpous mosses were more diverse than acrocarpous mosses. The collectors probably aimed at selecting material that was either characteristic of the vegetation in the respective areas of collecting or used for certain purposes (or both). The former hypothesis is supported by the small overlap in taxonomic diversity between the herbaria, and the latter by the fact that several moss, liverwort, and lichen genera are included whose traditional uses are well documented.