Dispersal and biogeography of silica-scaled chrysophytes

The silica-scaled chrysophytes—here mainly represented by the freshwater genera Mallomonas and Synura—have special problems in dispersal from one habitat to another because they cannot tolerate desiccation. Their dispersal is limited by the fragile construction and aquatic habit. Dispersal from one water body to another involves dangerous changes of the environment, and the ability to avoid desiccation during transport is crucial. So, air-borne and ectozoic dispersal by birds or mammals can only work at short distances. This danger may be avoided by endozoic dispersal of thick-walled cysts; as far as they can tolerate the digestion fluids in the intestine. In spite of these difficulties, Chrysophytes have been dispersed worldwide, but they display various distinct distribution patterns, e.g., cosmopolitan, arctic-northern temperate, bipolar, and tropical. Quite a large proportion may be considered endemic, occurring only within a restricted area. Even if the exact dispersal methods are elusive, the distribution of chrysophytes around the world proves their ability for dispersal. On the other hand, the different degree of distribution shows the varying success of the individual species. The distribution of a species at a given time depends on several factors: dispersal capacity—available vectors—suitable available habitats—and most important: sufficient time for dispersal. It is remarkable that the chrysophytes—in spite of their fragile cell construction and apparently low dispersal capacity—show distribution types comparable to those found in, e.g., blue–greens and desmids, whose cell construction appears much better adapted for dispersal. Special Issue: Protist diversity and geographic distribution. Guest editor: W. Foissner     

Silica-scaled chrysophytes (Synurophyceae) from some rivers and shallow lakes in Hungary

Silica-scaled chrysophytes are a special group in the phytoplankton of rivers and shallow lakes. They are present the whole year at low density, but sometimes — mainly during autumn and spring — some species can become frequent and very numerous to form real water blooms.In this study, seven species of silica-scaled chrysophytes have been recorded and identified by electron microscopy of phytoplankton samples from some rivers and shallow lakes in Hungary. Most of these silica-scaled chrysophytes have previously been found in eutrophic and hypertrophic localities, and almost all of them are common and widely distributed, even cosmopolitan. Only Synura echinulata Korshikov has not previously been recorded from Hungary. Some of them as Synura curtispina (Petersen & Hansen) Asmund, S. petersenii Korshikov, Mallomonas acaroides Perty emend. Ivanov, M. tonsurata Teiling were frequently found in the phytoplankton samples. Sometimes in autumn and winter Synura petersenii was the most abundant species in the phytoplankton and formed blooms.     

Mallomonadacean (Chrysophyceae) Scales: Early biotic paleoindicators of lake acidification

17 subfossil mallomonadacean species have been detected in the acidified Kleiner Arbersee. The most abundant one is M. crassisquama. In the top most layers, it is replaced by acid tolerant Synura spp. and several acidophilic and acidobiontic Mallomonas spp. Mallomonadaceae respond to acidification (and alkalinization) of lakes prior to benthic diatoms. Mallomonadaceae live euplanktically and mainly in spring, when most of the annual acid loading enters the lakes.     

Toxic cyanobacteria (blue-green algae) in Finnish fresh and coastal waters

A survey of the occurrence of toxic blooms of cyanobacteria in Finnish fresh and coastal waters was made during 1985 and 1986. Toxicity of the freeze-dried water bloom samples was tested by mouse-bioassay (i.p.). Forty-four per cent (83/188) of the bloom samples were found to be lethally toxic. Hepatotoxic blooms (54) were almost twice as common as neurotoxic ones (29). Anabaena was the most frequently found genus in toxic and non-toxic blooms and it was present in all neurotoxic samples. Statistical associations were found between hepatotoxicity and incidence of Microcystis aeruginosa, M. viridis, M. wesenbergii, Anabaena flos-aquae and Anabaena spiroides. Neurotoxicity was statistically associated with Anabaena lemmermannii, Anabaena flos-aquae and Gomphosphaeria naegeliana. Isolation of strains of cyanobacteria confirmed the occurrence of hepatotoxic and neurotoxic strains of Anabaena, as well as hepatotoxic strains of Microcystis and Oscillatoria species.Toxic blooms caused cattle poisonings at three different lakes during the study period. Toxic blooms also occurred in drinking water sources. Our study shows that toxic cyanobacteria are more common in Finnish lakes than would be expected on the basis of animal poisonings. The results of this study show the existence of toxic cyanobacteria in Finnish water supplies and the need for their continued study as agents of water based disease.     

High molecular mass glycoproteins associated with the siliceous scales and bristles of Mallomonas splendens (Synurophyceae) may be involved in cell surface development and maintenance

The elaborate scale case of Mallomonas splendens (Synurophyceae) consists of an overlapping arrangement of siliceous scales. In addition, siliceous bristles are attached to specialized base plate scales located at both the anterior and posterior ends of the cells. We have generated monoclonal antibodies against molecules associated with the scale case of M. splendens. One of these antibodies, designated MsS.H9, labelled a proteinaceous epitope of high-molecular-mass cell surface glycoproteins. Immunofluorescence and immunoelectron microscopy demonstrated that only two regions of M. splendens scale cases were labelled by MsS.H9, namely, the upper surface of the scales that contact neighboring scales and the bases of the bristles. Immunoelectron microscopy using thin sections of M. splendens cells showed these labelling sites corresponded to the amorphous material at the sites of scale-to-scale overlap and to a fibrillar complex located at scale-to-bristle attachment sites. Scales and bristles of M. splendens are formed within the cell, in silica deposition vesicles. Immunolabelling of cell sections containing developing scales and bristles showed that MsS.H9 labelling sites were present very early in the formation of these cell surface components. MsS.H9 labelling was also found associated with developing flagellar hairs whereas no labelling was detected on these structures after their deployment onto the flagellum. The location of MsS.H9 labelling sites strongly suggests that the molecule(s) recognized by the antibody plays a role in the adhesion of the individual components making up the scale case of M. splendens.Abbreviations CER chloroplast endoplasmic reticulum - ER endoplasmic reticulum - SDV silica deposition vesicle This work was supported by a grant from the Australian Research Council to R.W. We thank Dr. P. L. Beech for Fig. 13, Dr. L. Perasso for technical assistance and the Plant Cell Biology Group for the use of their monoclonal facilities.     

Three new species of Hyalella from Chile (Crustacea: Amphipoda: Hyalellidae)

Hyalella is the only epigean freshwater amphipod present in Chile . H. chiloensis, H. costera and H. kochi are here described and illustrated. H. kochi is distributed in highland areas of the Andes in northern Chile; it is characterized by a short ramus on uropod 3 and a hammer-shaped gnathopod 1. H. costera and H. chiloensis are present in lowland areas, the latter restricted to the southern part of the country. These two species have a long ramus on uropod 3, but they differ in the shape and length of the palp on maxilla 1, the setation of peraeopods 3, 4, and telson. The presence in Chile of H. fossamancinii Cavalieri, 1959 is also reported here.     

Reconstruction of pH by chrysophycean scales in some lakes of the Southern Alps

Chrysophycean scales were examined in surface sediments collected from 22 high mountain lakes on the southern slope of the Central Alps, some in Italy and some in Switzerland. The study area receives slightly acidic precipitation and summer lake pH ranges between 5.2 and 8.0. In each lake chrysophycean scale assemblage was dominated by one or two species and its composition was related to lakewater pH. Five short cores were examined in low-alkalinity lakes and evidence of recent lake acidification was found.     

The freshwater medusae of the world – a taxonomic and systematic literature study with some remarks on other inland water jellyfish

Several medusa species have been described from inland waters in Australia, Eurasia, Africa and America. The chief objective of this study is to summarize all species described from freshwater and from saline lakes, because the knowledge about this group is sparse and scattered in the literature. I summarize all accessible literature to deduct how many species of freshwater medusae exist and to show their distribution, relation and their phylogenetic origin.All medusae described from freshwater except Halmomises are Olindiidae (Limnomedusae). More than 20 Olindiidae species (in 6 genera) have been recorded from freshwater. However, about half of them may not be valid species or have been described insufficiently or improperly. Within the genera Craspedacusta only 3 (or 5) species are certain (C. sowerbii, C. iseanum, C. sinensis (and maybe C. sichuanensis and C. ziguiensis)). The genera Limnocnida may consist of 6 species, three from Africa (L. tanganjicae, L. victoriae, L. congoensis) and 3 from India (L. indica, L. biharensis, L. nepalensis). The status of Astrohydra (from Japan), Mansariella and Keralika (both from India) is uncertain. Additionally, the present study suggests that Craspedacusta and at least one type of Calpasoma hydrants are identical and Astrohydra may be closely related to Craspedacusta and/or Calpasoma.A comparison of the freshwater medusae with species described from saline lakes and brackish sites (Australomedusae from Australia and Moerisia from Egypt, Black Sea, Caspian Sea and Ganges Estuary) shows that these two groups are not closely related.     

The cyclopid (Crustacea,Copepoda) fauna of the inland waters of Israel

Four species of the genusMesocyclops (Cyclopoida: Cyclopidae) are reported from Israel:Mesocyclops kieferi Van de Velde, 1984,Mesocyclops aequatorialis similis Van de Velde, 1984,Mesocyclops ogunnus Onabamiro, 1957 andMesocyclops arcanus n.sp. The new species, close toM. kieferi, is described and some remarks are given for the other species.     

中国鹿角兰属(兰科)植物新资料

报道了中国兰科(Orchidaceae)鹿角兰属(Pomatocalpa)一新记录种——纹瓣鹿角兰［P. tonkinense (Gagnep.) Seidenf.］,凭证标本保存于广西植物研究所标本馆(IBK)。纹瓣鹿角兰的花序疏生多数花,萼片、花瓣均具2条紫色条纹,中萼片及花瓣远长于侧萼片,与中国原记录的2种鹿角属植物容易区分。该研究提供了新记录种的形态描述、中国鹿角兰属植物图版及分种检索表。     

Daphnia (Ctenodaphnia) Mediterranea: A new species of hyperhaline waters,long confused with D. (C.) Dolichocephala Sars, 1895.

A very particular form of Daphnia (Ctenodaphnia), adapted to life in epicontinental hyperhaline waters of Mediterranean arid regions had long been confused with Daphnia (Ctenodaphnia) dolichocephala Sars, 1895. In this paper the morphological and ecological differences between the two taxa are pointed out and comparison is made with another closely related Rumanian form (Daphnia cf. mediterranea) and with the related Spanish species (D. atkinsoni and D. chevreuxi). The Daphnia of saline environments is described here as Daphnia (Ctenodaphnia) mediterranea. The most important differential characters of this new species are: 1) the short and widely rounded rostrum; 2) dorsal ridge of the female extends to the anteriormost part of the head; 3) elliptical ephippium with a ride anterior margin; convex shape and separate from the dorsal ridge; 4) males possessing a very long antennule base that reaches the distal limit of the head.     

Structure and development of the scale case ofMallomonas adamas (Synurophyceae)

Summary The structure and development of the elaborate scale case ofMallomonas adamas (Synurophyceae) was studied throughout the cell cycle. Immediately following division, scale cases normally possess 30 siliceous scales, or 5 rows of 6 scales each. Scale rows overlap one another and spiral around the cell in a clockwise direction when viewed from either end of the cell. Throughout interphase, a duplicate set of 30 scales is manufactured and secreted into the existing scale case in a precise sequence, resulting in a scale case with 60 scales, or 5 rows of 12 scales each. Scales are not added to the scale case in rows, but individually positioned within the cytoplasm and inserted one at a time over the entire surface of the cell. Scales appear to occupy specific positions in the scale case. Scale cases are dynamic cell coverings, their elaborate patterning being maintained throughout cell growth and during division when half the parental scales are inherited by each daughter cell.     

Phytoplankton growth rates in the freshwater tidal reaches of the Schelde estuary (Belgium) estimated using a simple light-limited primary production model

During the course of 1996, phytoplankton was monitored in the turbid, freshwater tidal reaches of the Schelde estuary. Using a simple light-limited primary production model, phytoplankton growth rates were estimated to evaluate whether phytoplankton could attain net positive growth rates and whether growth rates were high enough for a bloom to develop. Two phytoplankton blooms were observed in the freshwater tidal reaches. The first bloom occurred in March and was mainly situated in the most upstream reaches of the freshwater tidal zone, suggesting that it was imported from the tributary river Schelde. The second bloom occurred in July and August. This summer bloom was situated more downstream in the freshwater tidal reaches and appeared to have developed within the estuary. A comparison between phytoplankton growth rates estimated using a simple primary production model and flushing rate of the water indicated that no net increase in phytoplankton biomass was possible in March while phytoplankton could theoretically increase its biomass by 20% per day during summer. Chlorophyllaconcentrations at all times decreased strongly at salinities between 5–10 psu. This decline was ascribed to a combination of salinity stress and light limitation. Phytoplankton biomass and estimated annual net production were much higher in the freshwater tidal zone compared to the brackish reaches of the estuary (salinity > 10 psu) despite mixing depth to euphotic depth ratios being similar. Possible reasons for this high production include high nutrient concentrations, low zooplankton grazing pressure and import of phytoplankton blooms from the tributary rivers.     

Two new species ofHalicyclops (Copepoda,Cyclopoida) from the Amazon Basin,Brazil

Two new species ofHalicyclops are described from plankton samples taken in two localities in the Amazon River mouth area, State of Pará, Brazil.Halicyclops lindbergi sp.n. resemblesH. hurlberti andH. clarkei from which it differs by a combination of characters in leg 5, the anal pseudoperculum and the caudal rami. The other new species,H. dussarti, is most morphologically similar toH. pilosus, but they are separated by differences in legs 1 and 5 as well as in the ornamentation of the middle caudal setae.     

Thalassomonhystera traesti n.sp., Eumonhystera andrassyi and three Monhystrella species (Monhysteridae: Nematoda) from Li River, China

A new Thalassomonhystera species, i.e. T. traesti n.sp., and a new subspecies, Monhystrella lepidura chinensis n. subsp., together with Eumonhystera andrassyi (Biró, 1969) Andrássy, 1981, Monhystrella macrura (de Man, 1880) Andrássy, 1981 and Monhystrella iranica Schiemer, 1965 are described from Li River at Guiling, China. Thalassomonhystera traesti n.sp. is characterised by a combination of the following characters: expanded lip region, large and anteriorly situated amphids, prominent inner labial sensilla, and slender spicules and tube-like gubernaculum in males. Monhystrella lepidura chinensis n. subsp. belongs to Monhystrella lepidura (Andrássy, 1963) Andrássy, 1968 but differs from the three hitherto described subspecies in its possession of a pharynx that posteriorly expands into a double bulb. Monhystrella macrura, M. iranica and Eumonhystera andrassyiare reported here for the first time from China.     

中国大陆壳状地衣3个新记录种

在对壳状地衣进行研究时,发现3个中国新记录种——颗粒类褐边衣(Trapeliopsis granulosa)、小疣巨孢衣易变变种(Megaspora verrucosa var.mutabilis)和黑墨衣(Placynthium nigrum),其中墨衣属(Placynthium)为中国新记录属。该文对这3个种的分类学特征进行了详细描述,并提供了它们的相关照片。     

Validation of the occurrence of the American eel Anguilla rostrata (Le Sueur, 1817) in free-draining European inland waters

The screening of 2,735 eels from European waters and aquaculture farms was conducted using mitochondrial Cytochrome b and 16S rRNA gene fragments amplified by polymerase chain reaction. Reaction products were either sequenced directly or subjected to analysis using restriction fragment length polymorphism which resulted in species-specific restriction patterns. Beside the expected European eel, Anguilla anguilla (Linnaeus, 1758), the American eel, Anguilla rostrata (Le Sueur, 1817), was also identified in samples from both aquaculture (N = 40 out of 1,025) and from natural waters (N = 44 out of 1,710). The life stages of American eels identified from several German waters draining to either the Baltic Sea and the North Sea ranged from elver to silver eels. This indicates that stocking with glass eels or elvers must have occurred several times most likely in the period from 1998 to 2002. The application of a fast and precise method for species identification and genetic monitoring of eels delivered for stocking is therefore essential for maintaining the autochthonous species composition in future. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

中国西藏棘虫兆科两物种的重新记述及中国已知种检索表（弹尾纲）

首次报道中国西藏棘科两物种:符氏直棘Orthonychiurus folsomi(Schffer,1900)和喜马拉雅直棘Orthonychiurus himalayensis(Choudhuri,1958),附详细描述及特征图;编制了中国棘科已知种类分种检索表。研究标本保存于中国科学院动物研究所动物标本馆。     

Morphological and molecular characterization of Anisakis larvae (Nematoda: Anisakidae) in Beryx splendens from Japanese waters

The third-stage (L3) larvae of Anisakis, which are the etiological agents of human anisakiasis, have been categorized morphologically into Anisakis Type I larvae and Anisakis Type II larvae. Genetic analysis has allowed easy identification of these larvae: Anisakis Type I larvae include the species Anisakis simplex sensu stricto, Anisakis pegreffii, Anisakis simplex C, Anisakis typica, Anisakis ziphidarum, and Anisakis nascettii, whereas Anisakis Type II larvae include the species Anisakis physeteris, Anisakis brevispiculata, and Anisakis paggiae. Since human consumption of raw fish and squid is common in Japan, we investigated Anisakis L3 larvae in 44 specimens of Beryx splendens from Japanese waters. A total of 730 Anisakis L3 larvae collected from B. splendens were divided morphologically into 4 types: Type I, Type II, and 2 other types that were similar to Anisakis Type III and Type IV described by Shiraki (1974). Anisakis Type II, Type III, and Type IV larvae all had a short ventriculus, but their tails were morphologically different. In addition, data from genetic analysis indicated that Anisakis Type II, Type III, and Type IV larvae could be identified as A. physeteris, A. brevispiculata, and A. paggiae, respectively. Therefore, A. physeteris, A. brevispiculata, and A. paggiae can be readily differentiated not only by genetic analysis but also by morphological characteristics of L3 larvae.