Polysiphonia perforans sp. nova (Ceramiales,Rhodophyta) from the Mediterranean Sea

ABSTRACT

A new species of the genus Polysiphonia from the Mediterranean Sea is described. It is an ecorticate species, with 4 pericentral cells, showing prostrate axes from which erect axes arise. Rhizoids are formed by pericentral cells in a median position remaining in open connection with them. Erect axes are straight, simple throughout or pseudodichotomous at the base then simple or with one (rarely two-three) orders of branching; trichoblasts and scar cells not observed. Only tetrasporangial plants were found. They show ellipsoid tetrasporangia borne in short straight series, often interrupted by sterile segments. The new species is also characterized by a peculiar habit consisting of prostrate axes, adhering to lower faces of Peyssonnelia spp. by means of rhizoids growing upward, from which erect upright axes perforating thalli of the supporting species arise. A comparison with the related species of Polysiphonia was also carried out.     

Induction of callus in the liverwort Marchantia palmata Nees

Abstract

In Marchantia palmata Nees, normal growth of thalli occurs on Nitsch's basal medium with 1% sucrose. With 4% sucrose, dark green callus is initiated by light intensities of 150–4,500 lux after 13–15 days of growth. In the dark only rhizoids develop from callus and at low light intensity (150 lux) rhizoids as well as knob-like green outgrowths differentiate. Increased light intensities induce differentiation of thalli and rhizoids from callus. The callus inducing effect of increased sucrose level can be replaced by higher concentrations of mannitol. Histological studies reveal that callus initially arises from the lower epidermis.     

Colourless tubers in Discelium nudum Brid

Abstract

Colourless, usually unicellular, tubers occur on the rhizoids of Discelium nudum. They are evidently not the rhizoid gemmae previously claimed to occur in this species, which were multicellular.     

Melanothamnus maniticola sp. nov. (Ceramiales,Rhodophyta): an epizoic species evolved for living on the West Indian Manatee

Over 35 macroalgae have been documented growing epizoically on sea turtles, and macroalgae are also known to grow on the West Indian Manatee, but the number and identity of these latter species have not been determined. Analysis of DNA sequences of 12 samples collected from different manatees captured in three areas of Florida indicated that they represented a single undescribed species within the Rhodomelaceae genus Melanothamnus. Morphological analysis revealed Melanothamnus characteristics but also a previously undescribed combination of character states. These include eight to nine, but as many as 11, pericentral cells; heavy cortication restricted to the base of thalli, and a sharp transition between the corticated and ecorticate sections of the thallus; cells surrounding the ostiole being similar in size to the outer pericarp cells immediately below, and robust rhizoids that have no terminal lobes and develop from central axial cell filaments instead of pericentral cells. The unique characteristics of the rhizoids may be evolutionary adaptations for anchoring the thalli to manatee epidermis. This species is described as M. maniticola sp. nov.     

NORTH CAROLINA MARINE ALGAE. XI. A NEW SPECIES OF HELMINTHOCLADIA (LIAGORACEAE,NEMALIALES, RHODOPHYTA) WITH A REAPPRAISAL OF THE GENERIC LIMITS OF HELMINTHOCLADIA AND HELMINTHORA1

A new species in the Liagoraceae (Nemaliales) having vegetative and male reproductive characteristics usually associated with the genus Helminthora is assigned to Helminthocladia (as Helminthocladia andersonii Searles & Lewis) on the basis of the shape of the conical carpogonial protoplast, three-celled carpogonial filament, development of the carposporophyte from both cells formed by division of the zygote and development of the involucre without the formation of a bridge around the zygote or formation of rhizoids from the involucre. All of these are consistent characteristics of Helminthocladia and distinguish its species from those of Helminthora.     

Orientation and righting behavior of the sand‐dwelling bryozoan Conescharellina catella

Most bryozoan colonies live firmly attached to hard surfaces, but some species live on sandy or muddy bottoms, anchored to the substratum by one or more rhizoids. The small, conical colonies of members of the genus Conescharellina live attached to the substratum by several rhizoids, each produced by a modified, non‐feeding zooid (kenozooid). It was previously thought that these colonies lived prone on the substratum, anchored but not supported by the rhizoids. In this study, I observed the behavior of a living colony of Conescharellina catella collected from the East China Sea and maintained in the laboratory for 2 months. The colony lived apex down, suspended above the substratum by several rhizoids arising in the apical two‐fifths of the colony, to a total height of nearly five times colony height. Starting from an uprooted position lying on the substratum, the colony reattached and righted itself to the erect position using existing or newly produced rhizoids. After I removed all rhizoids, the colony was able to right itself only after it regenerated rhizoids. In each of several series of observations, righting behavior involved similar steps and followed a similar time course, and it can thus be considered a stereotypical behavior. Histological sections showed that the rhizoids lack muscles. I speculate that righting is effected by differential turgor (internal pressure) and differential growth of rhizoids originating from kenozooids in different positions around the central colony axis, although it is unclear how the colony senses orientation and coordinates adjustments to achieve the preferred orientation.     

Hymenostylium xerophilum,sp. nov., and H. gracillimum,comb. nov., two neglected European mosses and their molecular affinities

Abstract

Hymenostylium xerophilum is described as a new species from the European Alps. Molecular rps4 and ITS data support its recognition and elucidate its affinities to other species of the tribe Pleuroweisieae. It is closely related to H. gracillimum, comb. nov., which is based on the old and neglected Gymnostomum gracillimum, which replaces the recent name G. boreale. Both species share non-coloured to pale yellowish-brown rhizoids, stem central strand and indistinct sclerodermis, keeled leaves, and concave laminae in abaxial view. They differ from each other in leaf shape and several essentially quantitative characters. Sporophytes have never been found in H. xerophilum, but they are known from several localities in H. gracillimum. The former colonizes rather dry, sunny to half-shaded calcareous rocks, whereas the latter needs moist and shaded rock habitats and shows a preference for subneutral slate. At present, H. xerophilum is known only from the Alps (Austria, and a single site in Germany), where it is rather widespread in calcareous regions. H. gracillimum seems to be a distinctly rarer plant, to date known only from eight Austrian sites and one locality in Russian Karelia. Other published records under the name G. boreale have been wrongly attributed to this species. Lectotypes are designated for G. gracillimum and Gyroweisia acutifolia. A key to Hymenostylium and the genera of Pleuroweisieae in Europe is presented.

Thicker rhizoids of both species are covered with a thick, non-coloured protective layer and filled with oil-droplets and leucoplasts. They represent a subterranean secondary protonema, which plays an important role in the survival and propagation of these mosses, vital especially in the case of the non-sporulating H. xerophilum.     

Germination of the Spores and Development of Primary and Secondary Protonema of Funaria hygrometrica

Abstract

1. The primary protonema of Funaria hygrometrica, cultivated on Knop's or Marchal's agar in the light, proved to consist of filaments with much chlorophyll, a hyaline membrane, perpendicular cross-walls and branches equal to the main filament (chloronema). These filaments grow on the surface of the agar, the branches may also grow vertically. Sometimes filaments with less chlorophyll occur immediately after the germination. The caulonema described by Sironval has not been observed. Thus the rhizoid-like forms mentioned in the literature should more likely be considered as a result of external conditions (see Schoene, Bauer, Heitz and Fitting). Therefore it remains doubtful if a distinction between rhizoids and chloronema on the primary protonema is of any importance as it is impossible to give a good definition of either form.

At the base of moss plants main filaments with brown membranes, oblique septa and without chlorophyll may develop (rhizoids). They grow on the surface or within the agar. In F. hygrometrica especially, the stem seems to influence the occurrence of these rhizoids. The main filaments form buds on the basal cell of the branches and thus serve for vegetative reproduction. The branches show the characteristics of the chloronema. This is contrary to the conclusion of Westerdijk that rhizoids would pass into chloronema only when they are damaged or when the growth of the end bud of the plant is inhibited. At the base of the plant, moreover, little ramified, short branches with oblique septa appear which do not produce buds.

2. Branches may develop in the first growth stages of the primary protonema at any point of the cells. One single cell of a main filament can produce none, one, or more than one branch. Later the branches appear immediately behind the acroscopic cross-wall except in a few cases. Each cell then produces one branch.

3. Buds always develop at the basal cell of a primary branch of a green main filament or of a rhizoid derived from a moss plant.

4. In two ways the protonema may fall into pieces, which can develop into new main filaments:

(a) By forming brood cells; rounded cells which get detached by splitting of the septum. This phenomenon is very frequent. Contrary to Servettaz's opinion it seems to occur particularly under unfavourable conditions.

(b) By forming special cells, tmemata, whose walls are rent. These occur on the primary protonema contrary to the observations of Correns and Bauer, but they are much less frequent than the brood cells. No observations have been made on the circumstances of their occurrence.     

Vandiemenia ratkowskiana Hewson (Marchantiophyta): a revised description and reassessment of its taxonomic status

Abstract

The endemic Tasmanian hepatic Vandiemenia ratkowskiana Hewson, originally referred to the family Vandiemeniaceae (Marchantiophyta), is restudied taxonomically. The rhizoids, female plants, calyptrae and sporophytes are described for the first time. These features are closest to those of Metzgeria (Metzgeriaceae) and support the placement of Vandiemenia within the Metzgeriaceae.     

Branched and swollen rhizoids in hepatics from montane rain forest in Peninsular Malaya

Abstract

Swollen and branched rhizoids are produced by flagellar axes in seven species of hepatics from montane rain forest. Rhizoid branching is associated with contact with the substratum whereas swollen tips contain abundant fungal hyphae.     

Spore germination and sporeling developlnent in Jungermannia sphaerocarpa Hook.

Abstract

The globular protonema of Jungermannia sphaerocarpa developed outside the spore wall in axenic culture. Up to six gametophytes were produced by each protonema, and sporeling development to the attainment of sexual maturity is described. Significantly fewer and larger oil bodies occurred in the rounded mature leaves compared with bifid immature leaves and with cells of the protonema. Within the numerous rhizoids, an intense purple pigmentation was developed and maintained.     

Immunolocalization of myosin in rhizoids ofChara globularis Thuill

Summary Myosin-related proteins have been localized immunocytochemically in gravity-sensing rhizoids of the green algaChara globularis using a monoclonal antibody against the heavy chain of myosin from mouse 3T3 cells and a polyclonal antibody to bovine skeletal and smooth muscle myosin. In the basal zone of the rhizoids which contain a large vacuole, streaming endoplasm and stationary cortical cytoplasm, the monoclonal antibody stained myosin-related proteins as diffusely fluorescing endoplasmic strands. This pattern is similar to the arrangement of subcortical actin filament bundles. In the apical zone which contains an aggregation of ER membranes and secretory vesicles for tip growth, diffuse immunofluorescence was detected; the intensity of the signal increasing towards the apical cell wall. The most prominent myosin-staining was associated with the surface of statoliths in the apical zone. The polyclonal antibody produced a punctate staining pattern in the basal zone, caused by myosin-related proteins associated with the surface of drganelles in the streaming endoplasm and the periphery of the nucleus. In the apical zone, this antibody revealed myosin-immunofluorescence on the surface of statoliths in methacrylate-embedded rhizoids. Neither antibody revealed myosin-immunofluorescence on the surface of organelles and vesicles in the relatively stationary cytoplasm of the subapical zone. These results indicate (i) that different classes of myosin are involved in the various transport processes inChara rhizoids; (ii) that cytoplasmic streaming in rhizoids is driven by actomyosin, corresponding to the findings onChara internodal cells; (iii) that actindependent control of statolith position and active movement is mediated by myosin-related proteins associated with the statolith surfaces; and (iv) that myosin-related proteins are involved in the process of tip growth.     

Obtaining plantlets from apical meristem of the red alga Gelidium sp.

For the first time, plantlets were obtained from fragments and cell aggregates (CA) of apical meristem of the red alga Gelidium sp. After two months of cultivation, an initial weight of 100 mg of fragments and CA from fresh meristem produced 3 g of plantlets without rhizoids. During the same period of cultivation, 100 mg of meristem fragments and CA isolated from thalli by the freezing-thawing procedure produced more than 20 g of plantlets with rhizoids. It is assumed that our methods for obtaining plantlets from fragments and CA of fresh and frozen-thawed meristem could be used to generate mass planting material for cultivation of algae (plantlets with rhizoids) in the sea and for tank-bubbling cultivation (plantlets without rhizoids). We speculate that meristem cells of frozen-thawed algae might be natural “seedstock” in the Arctic and Antarctic seas.     

BATRACHOSPERMUM HETEROCORTICUM SP. NOV. AND POLYSIPHONIA SUBTILISSIMA (RHODOPHYTA) FROM FLORIDA SPRING-FED STREAMS1

Polysiphonia subtilissima Mont. Is reported for the first time from a freshwater environment. The presence of four pericentral cells, subdichotomous branching, apical trichoblasts and rhizoids arising from pericentral cells combined with a lack of cortication and reproductive cells is consistent with marine populations of this species. The range of filament length is 1.4–4.7 cm. Branch diameters are 38–76 μm and pericentral cell lengths are 58–125 μm. Batrachospermum heterocorticum sp. nov. is distinguished primarily by a developmental change in cortical filaments from typical cylindrical cells (5.0–7.9 μm diam in initial stages to enlarged, elliptical cells (12.9–24.1 μm diam) in mature axes. Another unique feature of this species is carpogonia with cylindrical, pedicellate trichogynes on stringht carpogonial branches in mid to outer portions of lateral whorls. Other characteristics of B. heterocorticum include the following: olive-green color, 2–6 cm length, dichotomous to trichotomous fascicles in 4–7 tiers, 385–647 μm whorl diameters, 109–198 μm carpospore diameters and relatively small “chantransia” filaments.     

Notes on Lejeuneaceae: I. Microlejeunea diversiloba (Spr.) K.M.

Abstract

Previous work on the bryophytic component of dune communities has demonstrated changes in the representation of species with the progress of succession. The ability of some to act as pioneers and the restriction of others to later stages may be associated with their reactions to recurrent burial by wind-blown sand.

Eighteen species were selected for experimental investigation of the effects of sand burial, along the following lines:

(a) Transplants. Samples of eight species were transplanted to four sites representing different stages of the dune succession. Where the sand increment over 11 months exceeded about 4 cm. none survived but species found naturally in mobile dune areas emerged from about 3 cm. Those belonging to fixed dune communities survived only in the absence of burial, although on excavation all species showed some upward growth through the covering sand.

(b) Experimental burial, Method I: samples of the same eight species, grown in pots standing in water but not watered from above, were buried in sand to depths of 1, 2, 4, 5 and 6 cm. The maximum depth through which emergence took place was 4 cm., from which Ceratodon purpureus, Bryum pendulum and Brachythecium albicans reappeared. From shallower layers, however, a greater rate of emergence was shown by Tortula ruraliformis. Pseudoscleropodiun purum and Climacium dendroides did not survive depths greater than 2 cm., and 1cm. was the maximum for Hylocomium splendns and Rhytidiadelphus squarrosus.

Method II. Sample strips of fourteen species were placed in aquarium tanks and, apart from a small portion len exposed, were buried under a sand slope grading up to 7 cm. in depth. Watering was from above and the humidity was kept high by glass lids. The time taken for the appearance of shoots from increasing depths was recorded, also the periods required for reestablishment from increasing depths of 50% and 100% of the original shoot density. For species tested by both methods the results were in most cases similar. Marked powen of recolonization were also shown by Polytrichum piliferum, P. juniperinum and Pohlia annotina.

In P. annotina, Ceratodon purpureus and Dicramum scoparium re-establishment by means of vertically extending rhizoids producing protonemata at the surface is described.

The maximum depth from which the various species can emerge, the depths from which effective recolonization of the surface is achieved within a fairly short time, the ability to produce rhizoids in the overlying sand and the growth-form of the shoots on emergence are regarded as the most significant aspects of reaction to burial, in relation to the role of the species in their natural habitats.     

中国藓类植物无性繁殖体的初步观察

无性生殖在苔藓植物的生活史中起着重要的作用,并且常通过各种无性繁殖体来完成。无性繁殖体的形态常被用来辅助鉴定一些不育的藓类植物。本文通过对38种藓类植物的无性繁殖体进行显微观察,结果显示：无性繁殖体在不同的藓类植物之间已经过多次演化;无性繁殖体的形态在种内是相对稳定的,且与其着生位置、配子体的分枝方式密切相关,而与植物的系统位置以及生境并无直接的关系;无性繁殖体的颜色与其胞壁的厚度以及表面纹饰密切相关。此外,无性繁殖体的产生常常与假根、原丝体有共存关系。在研究中发现,藓类植物的无性繁殖体主要包括原丝体芽胞、无性芽胞（叶生芽胞、中肋芽胞、枝生芽胞）、芽体、假根芽胞和假根状块茎;其中原丝体芽胞和无性芽胞最为常见。     

Hypergravity can reduce but not enhance the gravitropic response ofChara globularis protonemata

Summary The relationship between the position of the statoliths and the direction and rate of tip growth in negatively gravitropic protonemata ofChara globularis was studied with a centrifuge video microscope. Cells placed perpendicularly to the acceleration vector (stimulation angle 90 °) showed a gradual reduction of the gravitropic curvature with increasing accelerations from 1g to 8g despite complete sedimentation of all statoliths on the centrifugal cell flank. It is argued that the increased weight of the statoliths in hypergravity impairs their acropetal transport which is induced when the cell axis deviates from the normal upright orientation. When the statoliths were centrifuged deep into the apical dome at 6g and a stimulation angle of 170 ° the gravitropic curvature after 1 h was identical to that determined for the same cells at 1g and the same stimulation angle. This indicates that gravitropism in Chara protonemata is either independent of the pressure exerted by the statoliths on an underlying structure or is already saturated at 1g. When the statoliths were moved along the apical cell wall at 8g and the stimulation angle was gradually increased from 170 ° to 220 ° the gravitropic curvature reverted sharply when the cluster of statoliths passed over the cell pole. This experiment supports the hypothesis that in Chara protonemata asymmetrically distributed statoliths inside the apical dome displace the Spitzenkörper and thus the centre of growth, resulting in gravitropic bending. In contrast to the positively gravitropic Chara rhizoids, no modifications either in the transport of statoliths during basipetal acceleration (6g, stimulation angle 0 °, 5 h) or in the subsequent gravitropic response could be detected in the protonemata. The different effects of centrifugation on the positioning of statoliths in Chara protonemata and rhizoids indicate subtle differences in the function of the cytoskeleton in both types of cells.Dedicated to Prof. Dr. Zygmunt Hejnowicz on the occasion of his 70th birthday     

Temperature effects on branch and rhizoid production in six species of Fontinalis

Abstract

Branching in Fontinalis occurs primarily in the range of 5 to 15°C and differs among the species. Pool conditions reduce branching significantly among most species and can account for the reduction in growth observed in those conditions.

Data on six species of Fontinalis support the hypothesis that Fontinalis produces more rhizoids in response to temperatures above 10°C and that this production will correspond with the summer season in the north temperate and arctic zones. Since branch production is not inhibited at 15°C and is only slightly reduced at 20°C, it appears that rhizoid production does not interfere significantly with branch production. Since rhizoid clumps often originate at branch innovations, the continuation of branching throughout the summer could aid the moss in attaching during the summer when its chances of success are maximum.     

Zschokkella mugilis N. Sp. (Myxosporea: Bivalvulida) from Mullets (Teleostei: Mugilidae) of Mediterranean Waters: Light and Electron Microscopic Description

A new Myxosporea, Zschokkella mugilis n. sp., was found in the gall bladder of several mugilids. It is distinguished from all previously reported Zschokkella from mugilids by the absence of valve ornamentation and from other species by the size of the spores. Prevalence of infection was 62.5% for Mugil capito, 70% for M. cephalus and 64.3% for Liza saliens. Plasmodia with rhizoids attached to epithelial cells appeared to compromise the host as evidenced in light and transmission electron micrographs presented herein. General ultrastructure and disporous sporogenesis of Z. mugilis resembled other Myxosporeans, but sporogonic cells did not seem to be formed in pansporoblasts.