SPORE WALL ULTRASTRUCTURE IN THE LIVERWORT ATHALAMIA HYALINA

Mature spores of Athalamia hyalina (Marchantiales, Cleveaceae) were examined with both scanning and transmission electron microscopes. Single, hollow, dome-like projections, sometimes having small pores and a coarsely granular surface texture, stud the spore surface, usually in a pattern of concentric circles. In section, the spore wall has an intine and two-layered exine. Intine-like material separates some lamellae of the inner exine, which is joined to the outer exine around the dome bases. Inner exine lamellae are composed of thin (5–6 nm), closely parallel membrane-like subunits. The outer exine is formed from a single large highly modified and doubly-coated lamella, the undulations of which form the surface domes. Dome cavities often are filled with a loose network of granular material.     

Miscellanea hepaticologica 201-210

Abstract

201. Calycularia crispula Mitt. new to Mexico and the whole America. It is the first record outside Asia. 202. A type study of Fimbriaria nana Lindenb. revealed that it is synonymous with Athalamia hyalina (Sommerf.) Hatt. 203. Fossombroniaceae Hazsl. 1885 has to replace Codoniaceae Klinggr.1858 nom. illeg., because Codonia Dum. 1822 is illegitimate. 204. Herzogobryumaterrimum (Steph.) c. n. (≡ Cephalozia aterrima Steph.) has to replace H. filarium Grolle 1975. 205. Korrnickia Steph. 1917 is regarded as a synonym of Symphyogyna Nees et Mont. 1836 and K. cylindrica Steph. 1917 is placed in synonymy of S. mexicana Steph. 1909.206. The detection of the perianth of Lophocolea spectabilis Steph. (≡ Heteroscyphus arnellii Fulf.) necessitates a transfer as Leptoscyphus spectabilis (Steph.) c. n. 207. All records of Preissia Corda from Latin America are rejected. P. barbata Herz. 1921 is referred to as syn. nov. of Marchantia chenopoda L. 1753. 208. Riccia crustata Trab. was validly published in 1916 already, but has been generally overlooked hitherto. 209. Symphyogyna brasiliensis. Nees et Mont. is widespread in the Neotropics and Africa. Several African names are treated as synonyms. 210. The monotypic genus Wiesnerella Schiffn. is newly recorded from New Guinea and the Mascarenes. The Mascarene record is the first one outside Asia.     

Amplified Fragment Length Polymorphism (AFLP) Reveals Species-Specific Markers in the Daphnia Galeata–HyalinaSpecies Complex

Daphnia often occur in species complexes that consist of two or more co-occurring species and their hybrids. Hybrid individuals are often capable of sexual reproduction and so backcrossing with introgression occurs. To better understand hybridization and backcrossing frequency, we sought to develop PCR-based, species-specific markers in the Daphnia galeata–hyalina species complex using amplified fragment length polymorphism (AFLP). This technique produces large numbers of reproducible markers for assessing diversity across the nuclear genome and provides several advantages over mtDNA and microsatellite approaches. We examined 28 clones of D. galeata, D. hyalina, and their hybrids isolated from Lake Constance on the Swiss-German border. Using a single AFLP primer combination we found five potential species-specific markers, defined as bands that occurred in >80% of one parental species and <20% of the other. Two bands appeared to be co-dominant and were present (homozygous) in D. galeata, absent in D. hyalina, and heterozygous in the hybrid. We conclude AFLP could provide enough PCR-based, species-specific markers to identify species, hybrids, and backcrosses from even small amounts of tissue (i.e. resting eggs).     

A new species of Boletopsis Associated with Pinus sylvestris L. in Scotland

Summary

The identity of a recent Scottish collection thought to be Boletopsis leucomelaena was examined with the help of molecular techniques. This poroid fungus proved to be a new species of Boletopsis differing from the European species occurring with Pinus sylvestris, which should continue to be called B. grisea. The new name Boletopsis peplexa is introduced for all the Scottish collections with Pinus sylvestris.     

Morphology and molecular phylogeny of epizoic araphid diatoms on marine zooplankton,including Pseudofalcula hyalina gen. & comb. nov. (Fragilariophyceae,Bacillariophyta)

Some diatoms are able to colonize as epibionts on their potential zooplankton predators. Here, we report Pseudohimantidium pacificum living on the copepod Corycaeus giesbrechti and as a new finding on Oithona nana, Protoraphis atlantica living on the copepod Pontellopsis brevis, Protoraphis hustedtiana on the cypris larvae of barnacles, and Falcula hyalina on the copepod Acartia lilljeborgii. The epizoic diatoms were able to grow as free‐living forms under culture conditions. Pseudohimantidium pacificum and P. atlantica appeared as the most derived species from their benthic diatom ancestors. The mucilage pad or stalk of the strains of these species showed important morphological distinction when compared with their epizoic forms. Barnacle larvae explore benthic habitats before settlement, and epibiosis on them is an example where P. hustedtiana profits from the host behavior for dispersal of its benthic populations. Molecular phylogenies based on the SSU rRNA and RuBisCO large subunit (rbcL) gene sequences revealed F. hyalina as an independent lineage within the Fragilariales (Tabularia, Catacombas, and others), consistent with its morphological distinction in the low number of rows (≤6) in the ocellulimbus, among other features. We propose the transfer of F. hyalina to the genus Pseudofalcula gen. nov. Molecular phylogeny suggests a single order for the members of the Cyclophorales and the Protoraphidales, and that the epibioses of araphid diatoms on marine zooplankton have been independently acquired several times. These clades are constituted of both epizoic and epiphytic/epilithic forms that evidence a recent acquisition of the epizoic modus vivendi.     

Swimming of Daphnia galeata x hyalina in response to changing light intensities: Influence of food availability and predator kairomone

Experiments showed that phototactic downward swimming in Daphnia galeata x hyalina as caused by a relative increase in light intensity (stimulus) is influenced by predator kairomone and food availability. The swimming responses at four different combinations of food availability and fish kairomone were analysed. Addition of both food and kairomone led to a significant increase in percentage of animals that responded to the light stimulus, but there was no significant interaction effect.We also found that kairomone and food had significant impact on displacement velocity and on the time between start of the stimulus and onset of the response.     

Lichen-rich pinewood,Cladonia ciliata-Pinus sylvestris community in north-eastern Scotland

Summary

Ground dominated by Cladonia lichens of the sub-genus Cladina was found locally on pinewood floors on sandy or gravelly soils in north-eastern Scotland. Most sites are under mature or old planted Scots pine, Pinus sylvestris, but some in younger plantations and a few in native pinewood. Nearly all are in areas of fairly dry climate, and all are in open situations with exposure to light and wind. The vegetation, prior to 1990 not a well recognized feature of Scottish pinewoods, is distinguished in this paper as a separate community, the Cladonia ciliata — Pinus sylvestris Community. It is part of the class Vaccinio-Piceetea and resembles the lichen-rich coniferous forests in the circumpolar boreal zone, but in Scotland occurs at the extreme climatic limit of this type of vegetation. Many stands are vulnerable to trampling and land-use change, and some have little protection against such environmental vicissitudes.     

Four different head shapes in Daphnia hyalina (Leydig) induced by the presence of larvae of Chaoborus flavicans (Meigen)

In many species of Daphnia spines, neck teeth, and enlarged or reshaped helmets are well-known as defences against invertebrate predators. Until now, Daphnia hyalina (Leydig, 1860), a common species in many European lakes, has appeared to be an exception to this rule.Here, we provide evidence that the larvae of Chaoborus flavicans (Meigen) also can induce morphological changes in D. hyalina. Specimens react morphologically to the presence of larvae in three ways: (a) by changes in the shape of head shield, (b) by the formation of spine(s) on the head, and (c) by the elongation of the tail spine. The frequency and intensity of these morphological changes are correlated positively with midge larvae densities. The most pronounced reactions occurred in young D. hyalina.The predator kairomone also induced changes in Daphnia body size.     

Sexual reproduction of the placental brooder Celleporella hyalina (Bryozoa,Cheilostomata) in the White Sea

The evolution of parental care is a central field in many ecological and evolutionary studies, but integral approaches encompassing various life-history traits are not common. Else, the structure, development and functioning of the placental analogues in invertebrates are poorly understood. Here, we describe the life-history, sexual colony dynamics, oogenesis, fertilization and brooding in the boreal-Arctic cheilostome bryozoan Celleporella hyalina. This placental brooder incubates its progeny in calcified protective chambers (ovicells) formed by polymorphic sexual zooids. We conducted a detailed ultrastructural study of the ovary and oogenesis, and provide evidence of both auto- and heterosynthetic mechanisms of vitellogenesis. We detected sperm inside the early oocyte and within funicular strands, and discuss possible variants of fertilization. We also detail the development and functioning of the placental analogue (embryophore) in the various stages of embryonic incubation as well as embryonic histotrophic nourishment. In contrast to all known cheilostome placentas, the main part of embryophore of C. hyalina is not a single cell layer. Rather, it is a massive “nutritive tissue” whose basal part is associated with funicular strands presumably providing transport function. C. hyalina shows a mixture of reproductive traits with macrolecithal oogenesis and well-developed placenta. These features give it an intermediate position in the continuum of variation of matrotrophic provisioning between lecithotrophic and placentotrophic cheilostome brooders. The structural and developmental differences revealed in the placental analogue of C. hyalina, together with its position on the bryozoan molecular tree, point to the independent origin of placentation in the family Hippothoidae.     

Contrasting migration behaviour of Daphnia pulicaria and D. galeata x hyalina, in avoidance of predation by 0+perch (Perca fluviatilis)

In spring and early summer, a small population of the large-bodied Daphnia pulicaria coexists with a much larger population of the medium-sized hybrid Daphnia galeata × hyalina in the epilimnion of Lake Maarsseveen (The Netherlands). When large shoals of juvenile perch (Perca fluviatilis) appear in the open water, both species start to migrate vertically. Since D. pulicaria has a larger body-size than D. galeata × hyalina, and is therefore competitive dominant over the hybrid, it is unlikely that both species interact via their common food resource, but they react both to fish predation. However, since they differ in size, and therefore in vulnerability for fish predation, both species adopt different strategies. The smaller bodied, and less vulnerable D. galeata × hyalina exhibits diel vertical migration ascending to the surface at dusk, and staying there during the night. In this way, benefiting from the higher temperatures of the surface layers. In contrast, the large-bodied, and more vulnerable D. pulicaria selects the deep cold hypolimnion water layers as refuge against fish predation. In this way it benefits from a safe habitat, free from fish predators, but on the other hand suffers from low water temperatures, which decrease its fitness. It is likely that the relatively higher temperature in the upper water layers serves as a proximate factor for the downward migration of D. pulicaria.     

Losses and gains to the Scottish Flora

Summary

Several examples are discussed of plants which have been exterminated from or introduced to Scotland as a result of human activities, and an attempt is made to draw lessons from these case histories. Four rare or threatened Scottish plants, Homogyne alpina, Mertensia maritima, Primula scotica, and Pteridium aquilinum ssy. latiusculum are considered to illustrate future plant conservation imperatives. Threats to the Scottish flora of a more “institutional” nature are discussed, and it is suggested that these point to the need for botanical societies to consider a more “campaigning” role.     

Illecebrum verticillatum L. in the outer Hebrides

Summary

Scottish habitats are here reviewed in a European context. Examples are selected in order to identify those recognisable as distinctively Scottish as well as others related to Scandinavian or European counterparts. The paper begins with a resumé of the main environmental influences in Scotland, then describes examples of habitats almost unique to, or best represented in Scotland. This is followed by reference to some distinctively western versions of more widely distributed habitats, and others corresponding to related types elsewhere. The bearing of this on site selection for nature conservation is discussed. Hitherto, in the UK selection for National Nature Reserves and Sites of Special Scientific Interest has been based largely on the criteria listed in A Nature Conservation Review (Ratcliffe, 1977). It is important, however, also to review Scottish habitats in a European context, as attempted in this paper. In making proposals (now approaching completion) for Special Areas of Conservation, to be recommended by the UK Government for adoption by the European Commission, it is now our duty to include not only habitats for which we have special responsibility because they are unique to or best represented in Scotland, or have distinctively western features, but also sufficient examples of all the main European types occurring in our country.

Nomenclature of British flowering plants and ferns follows Stace (1991).     

The relation of biotic and abiotic interactions to eutrophication in Tjeukemeer,The Netherlands

During the summer months of 1974–1985 chlorophyll-a and total P concentration, biomass of Daphnia hyalina, smelt Osmerus eperlanus, bream Abramis brema and pikeperch Stizostedion lucioperca, water temperature and water intake from lake IJsselmeer were monitored in Tjeukemeer. During this period there were manipulations with the bream and pikeperch stocks as a consequence of the termination of a gill-net fishery in 1977, and larval smelt immigrated each year from the large lake IJsselmeer and contributed largely to the yearly smelt recruitment.The correlation matrix of the nine variables mentioned above showed a positive correlation between bream and chlorophyll-a, but surprisingly a negative one between smelt and chlorophyll-a. The latter can only be explained when smelt is the dependent variable. In a multi-linear regression there was a negative effect of temperature, chlorophyll a and pikeperch on smelt and a positive effect of water intake. Daphnia hyalina was negatively influenced by the biomass of smelt and the water intake of lake IJsselmeer. The positive relation of Daphnia hyalina and chlorophyll-a was probably related to better survival chances of D. hyalina in an Oscillatoria-rich environment when smelt is the most important predator. An increasing biomass of bream coincided with higher total-P levels and probably contributed to higher chlorophyll-a levels.     

Are there allelopathic interactions in zooplankton? Laboratory experiments with Daphnia

Summary Daphnia hyalina and Daphnia cucullata were kept in flow-through chambers in lake water (I), water from mass cultures of D. hyalina (II) and water from mass cultures of D. cucullata (III). A good correlation between body length and clutch size of the Daphnia was found in all cases. The regression lines of the different treatments were compared with respect to different slopes and different intercepts. D. hyalina showed the same reaction to medium II and III, but a lower regression coefficient and higher intercept in medium I. In contrast D. cucullata showed the same reaction to medium I and II, but a higher regression coefficient in medium III.     

Lichen conservation in Scotland

Summary

The significance of the Scottish lichen flora is outlined within the context of the British Isles and Europe, prompting a cautionary note on an over-reliance of assessing conservation importance using national Red Data Book categorisations. The conservation needs of lichens and their habitats, from ‘gardening’ to landscape management are discussed.     

Comparative Studies of Ovicell Anatomy and Reproductive Patterns in Cribrilina annulata and Celleporella hyalina (Bryozoa: Cheilostomatida)

Investigations of the common boreal-arctic cheilostomate bryozoans Cribrilina annulata and Celleporella hyalina have shown that the two species possess similar ovicell structures and reproductive patterns. Both species are characterized by frontal dwarf ovicellate zooids, that are female autozooidal polymorphs in C. hyalina and simultaneous hermaphroditic autozooids in C. annulata. The latter species in addition has ovicellate autozooids of the usual type. Each ovicell is formed from a maternal zooid only, and its cavity is lined by the outer hemispherical fold (ooecium) and the distal zooidal wall. The coelomic cavity of the ooecium is separated from the body cavity of the maternal zooid by a transverse wall with simple pores. Each pore is closed by a cell plug, and the ooecia may be considered as kenozooids. Each oocyte is accompanied by a single nurse cell that degenerates after ovulation. The eggs are macrolecithal in C. annulata and microlecithal in C. hyalina, and the former species is a non-placental brooder whereas the latter forms a placenta. Fertilization is precocious. Possible mechanisms of sperm entry as well as oviposition are discussed. The literature concerning ovicell structure and development in cheilostomates is analysed. It is proposed that the brood chamber of cribrimorphs evolved by a fusion of costae and a reduction of the daughter zooid in ancestral forms. © 1998 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd. All rights reserved     

Analysis of reticulate relationships within the Daphnia longispina species complex. Allozyme phenotype and morphology

A two-step method is proposed to get reliable associations between morphology and genotype in clonal assemblages in which more than two predominantly parthenogenetic species are thought to coexist with hybrids. In dataset 1, the genetic relationships among clones of the Daphnia longispina hybrid complex from seven prealpine lakes in southern Germany were studied based on the variation at 21 enzyme loci. The spatial arrangement in the multidimensional scaling plot revealed a reticulate pattern among three presumably parental species, D. cucullata, D. galeata and D. hyalina, and three hybrid groups, D. cucullata/galeata, D. cucullata/hyalina and D. galeata/hyalina. The Got1 locus was believed to be a discriminating factor between species and hybrids (cf. Wolf and Mort, 1986). However, this locus is more variable, and 57% of the clones would have been misidentified using it. Moreover, the morphological variation within genetically defined groups is also higher than previously assumed. In dataset 2, the revision of morphological and genetic markers greatly improved the association between morphology and genotype in newly collected animals. The spatial arrangement of clones in multidimensional scaling plots and morphological asymmetries to parents suggest both, different degrees of introgression and bidirectional hybridization. Most unexpected genotypes were found in the cxh hybrid group, suggesting that F1-hybrids are fertile. The results showed (1) that the clonal diversity was very high (2) that detailed analyses of multiple morphological and allozyme markers are necessary to resolve taxonomic relationships within clonal assemblages consisting of multiple species, hybrids and differently introgressed backcrosses, and (3) that the three original species seem to have sufficient within-species recombination and a low enough rate of backcrossing to allow taxonomic identification. It must remain undecided if the present situation is locally restricted, if it is stable or represents a transient situation which could lead to either a consolidation of the three species by gradual elimination of the hybrids, to a taxonomic breakdown, or to hybrid speciation.     

A cross-phyla response to Daphnia chemical alarm substances by an aquatic oligochaete

Although chemical alarm substances from damaged heterospecifics have been well documented to induce defense mechanisms in potential prey, data about antipredator responses to alarm cues from prey organisms of a distinct phylum are scarce. In this study, we analyze the response of an oligochaete to chemical alarm substances from distantly related cladocerans. We conducted laboratory experiments to investigate whether the aquatic oligochaete Stylaria lacustris detects and responds to alarm substances from Daphnia. The oligochaetes were exposed to alarm substances from Daphnia magna, which is a member of the same prey guild, and D. hyalina, which is vulnerable to different predators. S. lacustris increased the fission rate in response to cues from conspecifics and the heterospecific D. magna. These species share common predators, especially damselfly larvae and hydras. In contrast, chemical cues released from D. hyalina did not induce an increase in the reproductive rate of the oligochaetes. D. hyalina is a pelagic species and is not included in the diet of predators preying upon S. lacustris. Our results indicate cross-phyla responses among invertebrates (Annelida and Arthropoda), and suggest strong selection pressures to respond to heterospecific alarm substances. The oligochaete S. lacustris is able to differentiate chemical substances released from damaged Daphnia of two different species. These results show that alarm cues released from damaged Daphnia may be species-specific. However, further studies on the chemical structure of alarm substances in cladocerans are needed to support this hypothesis.