Effect of Chelating Agents and Metal Ions on Gametangial Formation in the Moss Bryum argenteum Hedw

Chelating agents such as EDTA and EDDHA markedly stimulate theformation of gametangia in the dioecious moss Bryum argenteum,and the effect is more pronounced on male than on female clones.EDTA-stimulated gametangial formation is associated with significantincreases in endogenous iron and copper. Ferric citrate alsoenhances gametangial formation, but copper sulphate is inhibitory.The present findings are discussed in the context of earlierinvestigations on other plants in an attempt to explain thepossible involvement of chelating agents and metal ions in stimulatingthe onset of the reproductive phase in this moss. Bryum argenteum, gametangial formation, chelating agents, metal ions     

A new Eocene fossil of the genus Phycopeltis (Ulvophyceae,Chlorophyta)

A fossil of the aerophytic green algal genus Phycopeltis (Trentepohliaes, Ulvophyceae) dated to 35 Ma, is reported from the Pikopiko Fossil Forest, Southland, New Zealand. Previous reports of fossilized Phycopeltis have been subsequently synonymized with fungi by other authors; however, our specimen is not vulnerable to their criticisms. Inflated cells present in two approximately concentric rings are interpreted as gametangia, with irregular structures resembling the gametangial pores of modern material; sporophytic material is absent. The fossil resembles the modern disc‐forming species P. novae‐zelandiae, P. expansa, and P. arundinacea. The limited material available prevents the assignation of a specific epithet, but the habit and dimensions of the fossil clearly fall within those of modern representatives of the genus. Its single cell thickness throughout, absence of distinct melanization, and larger size demonstrate that it is not a fungal shield. The specimen constitutes arguably the most convincing fossil belonging to Trentepohliales, and the first unambiguously for the genus Phycopeltis. It is consistent in age with other known fossils of the order that, when combined with molecular evidence, suggests a terrestrial radiation far more recent than that of land plants.     

Microhabitat use,seasonal activity and diet of the snake-eyed skink (<Emphasis Type="Italic">Ablepharus kitaibelii fitzingeri</Emphasis>) in comparison with sympatric lacertids in Hungary

Microhabitat selection and seasonal activity of the snake-eyed skink, Ablephaus kitaibelii fitzingeri, are compared to the two lacertid lizards (Lacerta viridis and Podarcis muralis) that co-occur in many of its habitats. The food composition of A. k. fitzingeri is also described. Significant differences in microhabitat selection and seasonal activity among the three species were found. The snake-eyed skink was associated with open grasslands, and with a low level of scrub, bare soil and rock cover. The microhabitat preference of L. viridis was quite similar to that of the skink, but with a higher preference for scrub. P. muralis occurred in places with greater rock and bare soil cover, and more scrub than A. k. fitzingeri. Activity of the snake-eyed skink decreased dramatically in summer, probably because of the reduced thermal inertia originating from the extremely small size of this species, but its seasonal activity overlapped with those of the lacertids. Stomach content analysis of the snake-eyed skink suggests that it is a generalist predator of small, mainly flightless arthropod prey. Competition with juvenile lacertids and predation by adult L. viridis are conceivable for the snake-eyed skink.     

Regulation of gametangial formation in bryophytes

Under in vitro conditions gametangial formation in bryophytes can be regulated by a variety of physical and chemical factors. Liverworts are relatively more sensitive to photoperiod than are mosses. With the exception ofRiccia crystallina all species of liverworts thus far investigated are either long-day or short-day plants. Among mosses, all butSphagnum plumulosum appear to be independent of photoperiod for the onset of the reproductive phase. The photoperiodic response in liverworts increases with increasing light intensity. Mosses, on the other hand, exhibit differential behavior.Leptobryum pyriforme andBartramidula bartramioides exhibit a linear relationship with light intensity for this response, whereasBryum argenteum, B. coronatum andBarbula gregaria have a specific light intensity requirement for optimal response. The photoperiodic effect in bryophytes is operative within certain temperature limits. Most bryophytes do not require a low temperature pretreatment for gametangial induction. Some become fertile in a broad temperature range, whereas others require a specific temperature. Among chemical factors, carbohydrates in general enhance gametangial formation.Riccia crystallina andBartramidula bartramioides develop gametangia in the presence of a carbohydrate, butBryum spp. (B. argenteum andB. coronatum) andBarbula gregaria respond even in its absence. High carbohydrate-nitrogen ratio seems more favorable for the onset of reproductive phase. Bryophytes respond differentially to various forms of nitrogen. Depletion of inorganic nitrogen (nitrate or ammonium) significantly favors gametangial induction. On the other hand, organic nitrogen (such as amino acids, peptone and urea) has differential effects on the enhancement of antheridial and archegonial formation in liverworts. Growth hormones have variable effects on gametangial induction. Indole-3-acetic acid increases archegonial formation inRiccia crystallina, but it is more favorable for antheridial production in mosses likeBryum coronatum, B. argenteum andBarbula gregaria. Gibberellins enhance antheridial formation in all the investigated bryophytes. Cytokinins stimulate induction of archegonia and inhibit antheridial formation inRiccia crystallina andBryum argenteum. Auxins, gibberellins and cytokinins also interact in eliciting the response. Iron and copper chelating agents such as EDTA and EDDHA favor vegetative growth and gametangial formation. InRiccia these chelates enhance archegonial production more than antheridial formation, but inBryum argenteum their effect is just the reverse. Salicylic acid, known to chelate iron and copper in certain animal systems, inhibits gametangial formation in most bryophytes, except inBartramidula in which it enhances vegetative growth as well as gametangial formation. InBryum argenteum the effect of these chelates is accompanied with marked changes in the endogenous levels of iron and copper. Iron appears to favor the onset of reproductive phase, whereas copper is inhibitory. Cyclic AMP, a well known mediator of hormone action in animal systems, enhances gametangial formation inBryum argenteum. The response is specific and is mimicked by phosphodiesterase inhibitors. Cyclic AMP also increases antheridial production inBryum coronatum andBarbula gregaria. InBryum argenteum it overcomes the inhibitory effect of ammonium ions and high concentrations of sucrose on gametangial formation. In addition to the above factors, pH and nutritional status of the medium also affect the onset of reproductive phase. Bryophytes exhibit maximum response in a definite pH range. Moreover, a specific change in pH of the medium is observed during gametangial initiation. Nutritional status, as affected by the concentration of nutrients in the medium, has varied effects on gametangial formation. In most instances dilution of the medium is more favorable for the response. Certain other factors, such as yeast extract and animal sex hormones, also enhance the formation of antheridia and archegonia. The onset of the reproductive phase involves metabolic changes in the differentiating tissues. Archegonial initiation is accomplished by intense metabolic activities, and in certain liverworts there is an increase in the content of carbohydrates, auxins, RNA and proteins, whereas the level of total nitrogen drops. Besides this a number of enzymes and phenolic compounds also exhibit marked qualitative and quantitative changes. Once gametangia are induced under in vitro conditions, fertilization can be accomplished by flooding the cultures bearing mature gametangia with sterile, distilled water. Development of sporophytes is markedly affected by temperature and nutritional status of the medium.     

Deposition of moss spores in relation to distance from parent gametophytes

Abstract

Daily counts were made of spores trapped on microscope slides coated with petroleum jelly and placed on the ground at distances up to 200 em from isolated colonies of Atrichum undulatum and Bryum argenteum. The observations continued for 30–34 days during the annual period of spore release in these species. Estimates of the number of spores released by the colonies were obtained as the product of the numbers of capsules and the difference between the mean numbers of spores present in undehisced capsules at the beginning of the experiment and remaining in dehisced capsules at the end.

Spore deposition over the experimental periods showed a steep gradient, deposition per unit area falling from 4740—14, 230 spores cm_?2 in the centre of the colonies to less than 10 spores cm_?2 200 cm from the edge of the colonies. Despite the steep deposition gradients, however, it was estimated that more than 85% of the spores in A. undulatum, and more than 95% of those in B. argenteum, were dispersed to unknown distances beyond the trapping areas.     

Some interesting Orthotrichum species from mainland Greece and Evvia

Abstract

Based on collections made by the authors in mainland Greece, including the Peloponnese and the island of Evvia, several Orthotrichum records of interest are documented. Orthotrichum acuminatum, O. philibertii, O. tortidontium, O . hispanicum, O. macrocephalum and O. shawii are reported for the first time from Greece, the last three also being new to the eastern Mediterranean. O. rivulare, O. scanicum, and O. alpestre, hitherto doubtfully recorded, are confirmed for Greece and new localities are given for O. stramineum, for which there are few previous records.     

Rhodobryum commersoni(Schwaegr.) Par. and R. aubertii (Schwaegr.) Thér. in South India.

Abstract

A new species Tristichella dimorpha is described and illustrated and a comparison made with the two other species in the genus, T. spiculifera and T. glabrescens, and with Clastobryella cuculligera to which it appears to be closely related, particularly in sporophytic characters.     

The effects of thermal biology and refuge availability on the restricted distribution of an alpine lizard

Aim In an effort to disentangle the ecological processes that confine ectotherms to alpine environments, we studied the thermoregulatory and microhabitat selection behaviours of the rock lizard Iberolacerta cyreni, which is endemic to some mountains of central Spain, and of the wall lizard Podarcis muralis, which is a potential competitor of rock lizards. Location We chose three areas in the Sierra de Guadarrama (central Spain) that differed in their thermal quality [mean deviation of environmental operative temperatures from the lizards’ preferred thermal range (PTR)] and refuge availability: a pine forest (1770 m a.s.l.) in which P. muralis was the only species found, and two mixed shrub and rock sites (1770 and 1900 m a.s.l.) where both species were present. Methods In the field we collected data on refuge availability, sun exposure, body temperature (T_b) and operative temperature (T_e). Thus, we estimated the thermal habitat quality of the areas sampled and the thermoregulation accuracy and effectiveness of both species. Results The pine forest had the lowest thermal quality and refuge availability. The lower‐elevation shrub site offered the best thermal quality, but refuges were much scarcer than at the higher‐elevation site. Both species thermoregulated accurately, because mean deviations of body temperature (T_b) from PTR were considerably smaller than those of T_e. Podarcis muralis had higher T_b values than did I. cyreni, which had similar T_b values at both shrub sites, whereas P. muralis had lower T_b values at higher elevation. Overall, the thermoregulatory effectiveness (extent to which T_b values are closer to the PTR than are T_e values) of both species was similar, but whereas I. cyreni thermoregulated more efficiently at higher elevation, the opposite was true for P. muralis. At the lower‐elevation shrub site, I. cyreni remained closer to refuges than did P. muralis. Main conclusions Our results suggest that the pine forest belt might prevent the expansion of rock lizards towards lower elevations as a result of its low thermal quality and scarcity of refuges, that the thermoregulatory effectiveness of rock lizards in alpine environments depends more on refuge availability than on thermal habitat quality, and that competition with wall lizards is unlikely to explain either the distribution or the thermoregulatory effectiveness of rock lizards.     

Stucture and reproduction of Cordylecladia guiryi sp. nov. (Rhodophyta,Rhodymeniales) from the Mediterranean Sea

Abstract

Cordylecladia guiryi sp. nov. is described from the Mediterranean Sea, after a comparison of habit, morphology and reproduction with C. erecta, the only species of the genus. The species is characterized by the small dimension of its axes which arise single from the basal crust and by its habitat, growing epiphytically on Posidonia oceanica Delile leaves. Tetrasporangial and gametangial plants as well as the development of the carposporophyte have been studied in detail. The carpogonial branch is 4-celled and it is formed on a supporting cell that also bears a 3-celled auxiliary branch. Tetrasporangia are cruciately divided. The reproductive details confirm Sparling's view about the great variation existing in the organization of the procarp in members of this order.     

Effetti del cobalto,nichel e cromo sulla germinazione di Alyssum,durante il ciclo di postmaturazione e invecchiamento

Abstract

Cobalt, nickel and chromium effects on germination of Alyssum, during after-ripening and aging. Cobalt (2.5–20mM), nickel (2.5–25mM) and chromium (0.2-1mM) effects have been studied in seeds of three species of Alyssum, of which two, A. bertolonii and A. argenteum, endemics to serpentine soils and one, A. nebrodense, closely related to the others but endemic to the Madonie (Sicily) where it grows on limestone.

The results, expressed as percentage of germinated seeds (p), Kotowski coefficient of velocity (v) and germination average ratio (pτ), have been subjected to statistical analysis.

The effect per mM is generally inhibitory, not significant for cobalt, weak but significant for nickel, more marked and significant for chromium, linearly correlated to concentration. The inhibition reaches its highest level when seeds are ripe, being significantly related to the control germination capacity (pτ).

The values of the specific inhibition (effect/mM modditppτ) for all the three species are higher for chromium, which is more toxic than nickel, and increase from A. nebrodense to A. argenteum, showing that of the two serpentine endemics A. bertolonii is more tolerant both to nickel and chromium.     

Sex ratio and sex expression in an urban population of the silver moss,Bryum argenteum Hedw.

ABSTRACT

Introduction. A well-supported pattern among dioicous bryophytes is male rarity. However, few assessments of bryophyte sex ratios have been made across environmental gradients to assess the role of environment in shaping population sex ratios.

Methods. We systematically surveyed 200 shoots from a 20?m² urban population of Bryum argenteum, and regenerated each shoot apex until sex expression occurred (up to 315 days).

Key results. Female shoots outnumbered male shoots 132 to 68, giving a sex ratio of 1.94♀: 1♂. The female bias was found in two transects in higher light environments but not in the third transect, which had a lower light level and an equal sex ratio. Female shoots took longer than male shoots to reach gametangial induction (122 vs. 60 days) and longer to produce 5 inflorescences (120 vs. 80 days). Male shoots produced an average of 10× the total number of inflorescences compared to female shoots (34 vs. 3.5 inflorescences). Despite producing more inflorescences, male plants also produced more regenerant shoots, thus contradicting the prediction that a higher prefertilisation reproductive effort in males trades off with vegetative proliferation. Female plants harboured significantly more associated microbes than male plants.

Conclusions. Our results support the role of light in influencing sex ratios in this species, suggest that trade-offs between reproduction and vegetative growth may not be strong for males, and indicate a potential role of a sex-specific microbiome in influencing sex ratios.     

Novelties in spermacoceae (Rubiaceae) from Bolivia and Paraguay

One new Bolivian species (Borreria pazensis) and three new varieties (Borreria densiflora var.minima, Richardia, scabra var.chacoensis andStaelia virgata var.killeenii) are described and illustrated. The genusDiodella, with three species (D. apiculata comb. nov., D. radula comb. nov., andD. teres), is reported for the first time.Borreria limae, B. wunschmannii, B. scabiosoides var.scabiosoides, andB. scabiosoides var.anderssonii are also reported as new to Bolivia.     

Conjugation processes of Penium margaritaceum (Zygnemophyceae,Charophyta)

Detailed conjugation processes in Penium, a unicellular conjugating green alga, are described for the first time. A homothallic strain of Penium margaritaceum (Ehrenb.) Bréb. (Designation, izu84‐10) was isolated from a rice paddy field in Japan. The species was identified based on its morphology, and a molecular phylogeny confirmed that izu84‐10 was closely related to another identified strain of this species. Using time‐lapse photography, the conjugation processes in P. margaritaceum were observed and then categorized into the following six stages: (1) cell division, resulting in the formation of two sister gametangial cells from one vegetative cell; (2) formation of a sexual pair between the two sister gametangial cells (or between gametangial cells of another nearby individual); (3) formation of conjugation papillae by elongation of the cell wall; (4) release of a gamete from one of the pair members; (5) release of a gamete from the other pair member; and (6) formation of the zygospore by gamete fusion. By alcian blue staining, possible involvement of mucilage to facilitate this cell adhesion and cell–cell communication was suggested.     

Multiple colonization and dispersal events hide the early origin and induce a lack of genetic structure of the moss Bryum argenteum in Antarctica

The dispersal routes of taxa with transoceanic disjunctions remain poorly understood, with the potential roles of Antarctica not yet demonstrated. Mosses are suitable organisms to test direct intra‐Antarctic dispersal, as major component of the extant Antarctic flora, with the cosmopolitan moss Bryum argenteum as ideal target species. We analyzed the genetic structure of B. argenteum to provide an evolutionary time frame for its radiation and shed light into its historical biogeography in the Antarctic region. We tested two alternative scenarios: (a) intra‐Antarctic panmixia and (b) intra‐Antarctic genetic differentiation. Furthermore, we tested for evidence of the existence of specific intra‐Antarctic dispersal routes. Sixty‐seven new samples (40 collected in Antarctica) were sequenced for ITS nrDNA and rps4 cpDNA regions, and phylogenetic trees of B. argenteum were constructed, with a focus on its Southern Hemisphere. Combining our new nrDNA dataset with previously published datasets, we estimated time‐calibrated phylogenies based on two different substitution rates (derived from angiosperms and bryophytes) along with ancestral area estimations. Minimum spanning network and pairwise genetic distances were also calculated. B. argenteum was potentially distributed across Africa and Antarctica soon after its origin. Its earliest intra‐Antarctic dispersal and diversification occurred during a warming period in the Pliocene. On the same timescale, a radiation took place involving a dispersal event from Antarctica to the sub‐Antarctic islands. A more recent event of dispersal and diversification within Antarctica occurred during a warm period in the Pleistocene, creating favorable conditions also for its colonization outside the Antarctic continent worldwide. We provide evidence supporting the hypothesis that contemporary populations of B. argenteum in Antarctica integrate a history of both multiple long‐range dispersal events and local persistence combined with in situ diversification. Our data support the hypothesis that B. argenteum has been characterized by strong connectivity within Antarctica, suggesting the existence of intra‐Antarctic dispersal routes.     

Delayed fluorescence as a new screening method of plant species for urban greening: an experimental study using four bryophytes

Selecting suitable plant species is important in urban greening because urban environments often provide unfavorable conditions for plant growth. We focused on delayed fluorescence (DF), i.e., light emitted from plants immediately following light exposure as a result of back electron transfer in photosynthesis, as an indicator of photosynthetic activity. Moss greening, urban greening using bryophytes, has attracted attention as a new domain of greening that does not require soil. Therefore, tolerance to drying, which is a characteristic environmental factor in cities, of four bryophytes—Bryum argenteum Hedw., Racomitrium japonicum Dozy et Molk., Hypnum plumaeforme Wilson, and Polytrichum commune Hedw.—was evaluated in the laboratory using DF. Assuming an urban environment, experiments were performed to measure the transition of DF following the cessation of irrigation and re-watering. The recovery of accumulated DF values (0–200 s) by rehydration 8 days after irrigation cessation was increased in the order H. plumaeforme ≈ P. commune?<?R. japonicum?<?B. argenteum. B. argenteum presented an increase in the accumulated amount of DF 8 h after irrigation cessation, and presented a significantly higher DF when compared with the other three species at 16 h. Together with results of previous studies, these findings of desiccation tolerance in the studied species indicate that DF is a useful method for characterizing desiccation tolerance in plants and selecting potentially useful plants for urban greening.

     

How to define nativeness in vagile organisms: lessons from the cosmopolitan moss Bryum argenteum on the island of Tenerife (Canary Islands)

The distinction between native and introduced biotas presents unique challenges that culminate in organisms with high long‐distance dispersal capacities in a rapidly changing world. Bryophytes, in particular, exhibit large distribution ranges, and some species can truly be qualified as cosmopolitan. Cosmopolitan species, however, typically occur in disturbed environments, raising the question of their nativeness throughout their range. Here, we employ genetic data to address the question of the origin of the cosmopolitan, weedy moss Bryum argenteum on the island of Tenerife. The genetic diversity of B. argenteum on Tenerife was comparable to that found in continental areas due to recurrent colonisation events, erasing any signature of a bottleneck that would be expected in the case of a recent colonisation event. The molecular dating analyses indicated that the first colonisation of the island took place more than 100,000 years ago, i.e. well before the first human settlements. Furthermore, the significant signal for isolation‐by‐distance found in B. argenteum within Tenerife points to the substantial role of genetic drift in establishing the observed patterns of genetic variation. Together, the results support the hypothesis that B. argenteum is native on Tenerife; although the existence of haplotypes shared between Tenerife and continental areas suggests that more recent, potentially man‐mediated introduction also took place. While defining nativeness in organisms that are not deliberately introduced, and wherein the fossil record is extremely scarce, is an exceedingly challenging task, our results suggest that population genetic analyses can represent a useful tool to help distinguish native from alien populations.     

Mecranium juddii (Melastomataceae: Miconieae), a new species from the Massif de la Hotte, Haiti

Mecranium juddii is described and illustrated. It is known only from 1650–1700 m elevation in the Ravine du Sud on the northern slopes of Morne Formon in Macaya National Park, Haiti.Mecranium juddii is a member of theM. multiflorum complex and is phenetically most similar toM. revolutum andM. alpestre, which differ fromM. juddii in stem indumentum or leaf size and shape.     

Patterns of cranial ontogeny in lacertid lizards: morphological and allometric disparity

We explored the ontogenetic dynamics of the morphological and allometric disparity in the cranium shapes of twelve lacertid lizard species. The analysed species (Darevskia praticola, Dinarolacerta mosorensis, Iberolacerta horvathi, Lacerta agilis, L. trilineata, L. viridis, Podarcis erhardii, P. melisellensis, P. muralis, P. sicula, P. taurica and Zootoca vivipara) can be classified into different ecomorphs: terrestrial lizards that inhabit vegetated habitats (habitats with lush or sparse vegetation), saxicolous and shrub‐climbing lizards. We observed that there was an overall increase in the morphological disparity (MD) during the ontogeny of the lacertid lizards. The ventral cranium, which is involved in the mechanics of jaw movement and feeding, showed higher levels of MD, an ontogenetic shift in the morphospace planes and more variable allometric patterns than more conserved dorsal crania. With respect to ecology, the allometric trajectories of the shrub‐climbing species tended to cluster together, whereas the allometric trajectories of the saxicolous species were highly dispersed. Our results indicate that the ontogenetic patterns of morphological and allometric disparity in the lacertid lizards are modified by ecology and functional constraints and that the identical mechanisms that lead to intraspecific morphological variation also produce morphological divergence at higher taxonomic levels.