OBSERVATIONS ON CHAETOCEROS BUCEROS (BACILLARIOPHYCEAE), A RARE TROPICAL PLANKTONIC SPECIES COLLECTED FROM THE MEXICAN PACIFIC1

Examination of net plankton samples from the Gulf of Tehuantepec (Mexican Pacific) yielded a rare tropical species of the genus Chaetoceros, C. buceros Karsten. This species is conspicuous because of its relatively large size, type of chain formation, and shape of the terminal setae. Electron microscopic study revealed other interesting characteristics: the intercalary values are more lightly silicified than the terminal valves and show a pattern of costae radiating form the center with various annuli (“central hyaline fields”) in the center of the valve face; both kind of valves are perforated by small poroids. Terminal valves possess several (21–30) slitlike and randomly oriented rimoportulae. Important morphological differences exist between the intercalary and the terminal setae. Morphological characters, comparision with related species, and the systematic position are discussed. A new section of the subgenus Hyalochaete, Conspicua, is proposed to include C. buceros.     

Global diversity of two widespread,colony‐forming diatoms of the marine plankton,Chaetoceros socialis (syn. C. radians) and Chaetoceros gelidus sp. nov.

Marine phytoplankton samples containing diatoms of the Chaetoceros socialis group were collected from Thailand, China, Denmark, and Greenland, and cells were isolated into culture for light and electron microscopy and DNA sequencing of D1–D3 of the LSU rDNA. Species of this lineage are characterized by three short and one long setae extending from each cell, the long setae from several cells joining into a common center to form large colonies, which are sometimes visible with the naked eye. Phylogenetic analyses including sequences from other parts of the world revealed segregation into three groups. Most sequences fell into two large clades, one comprising material from cold waters, whereas the other contained material from warmer waters. Strain CCMP 172 from the Strait of Georgia, Washington State, USA, formed a separate group. The warm‐water species included Chinese and Thai material and therefore probably also material from the type locality of C. socialis, Hong Kong. It is characterized by all setae being covered by spines and the setae extending from the valve at some distance from the margin. In the resting spores, both valves are ornamented with spines. The cold‐water material is characterized by three spiny and one mostly smooth long setae, and the setae extend from the valve near the margin. Both valves of the resting spore are smooth. This material is described as C. gelidus sp. nov. C. radians, described from the Baltic in 1894, is considered a synonym of C. socialis. CCMP172 is in many ways intermediate and probably constitutes a separate species. The published evidence on this globally distributed and sometimes bloom‐forming group of species indicates higher species diversity than presently thought.     

Two new species of the diatom genusChaetoceros (Bacillariophyta)

Two new planktonic diatom species of the genusChaetoceros are described herein:Ch. octagonus andCh. rectus, from material of Baja California coasts and the Gulf of California, respectively;Ch. rectus was also found in a sample from Australian waters.Ch. octagonus is a robust species, with a characteristic pyramidal valve shape, heavily silicified valves and setae, and one central rimoportula on every valve in the chain; it is compared with related species, which show a similar morphology, especially by electron microscopy. It belongs into subg.Chaetoceros, sect.Borealia. Ch. rectus is placed in subg.Hyalochaete, and provisionally within sect.Anastomosantia. Its major characters are: chains, cells, and setae are delicate and fragile, cells are joined in the chain by a bridge which connects sibling intercalary setae, valves and setae are weakly silicified, and one rimoportula is present on terminal valves only. Comparison is made with another species of the same section.Ch. rectus shows a different manner of chain-forming within the genus than previously described in the literature.     

Observations on Chaetoceros salsugineus (Chaetocerotales,Bacillariophyceae): first record of this bloom-forming diatom in a European estuary

Examination of material obtained from the Urdaibai estuary (North Spain) during a 2 year phytoplankton sampling programme revealed a rare species of the genus Chaetoceros, C. salsugineus Takano. The morphology of this small (4·0×5·5?µm) member of the subgenus Hyalochaetae has been described using both light and electron microscopy. Regarding the original material, two new features have been observed: longer chains up to 24 cells and a new type of aperture, bisected by the fusion of central protuberances of adjacent valves. This bloom-forming diatom reached high densities in the poly-euhaline zone of the estuary closely related with high temperatures, denoting its neritic and summer preferences. Maximal cell densities (10⁶–10⁷ cells l^?1) were reached in August and September when the water column was completely mixed and the salinity and temperature were about 31 psu and 20°C, respectively. This is the first report of C. salsugineus in Europe and contributes to the knowledge of the morphological and ecological features of this species. Relationships with other small species of the subgenus Hyalochaetae are also discussed.     

Two new species of Diaphanosoma Fischer, 1850(Crustacea: Branchiopoda: Cladocera) from the United States

Two new species of the genus Diaphanosoma, D. oligosetum and D. dorotheae, from Louisiana and North Carolina respectively, are described. The former species has large head with protruding dorsal part, large lanceolate spine on the basipodite's distal outer end, an extremely reduced number of antennal setae, up to six in adult specimens, and unique armament of valve margin. On the whole, it shows the pronounced combination of primitive and specialized morphological traits. D. dorotheae is a member of D. brachyurum species group differing from its other known representatives in presence of a small but very conspicuous spine on the end of proximal segment of antennal exopodite and a variable number of setae (seven or eight) on the distal segment of the branch. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Chaetoceros sumatranus,a member of Chaetoceros section Coarctati,sect. nov. (Bacillariophyceae)

During different surveys of phytoplankton in the Gulf of California, along the coasts of Baja California, the Gulf of Tehuantepec, and the Mexican Caribbean Sea, new records of diatoms have been made and new species (mainly of the genus Chaetoceros) have been described. This study shows that the planktonic diatom Chaetoceros sumatranus, a rather rare tropical to subtropical taxon, is a typical species of the subgenus Chaetoceros (syn.: Phaeoceros) with robust cells forming chains, thick setae, reduced apertures and small, rounded chloroplasts in cells and setae. Additionally, the species exhibits other singular characteristics, such as heteropolarity of chains, distinct bases of the setae and a pattern of several rimoportulae in every valve of the chain. These features indicate that C. sumatranus is a species closely related to C. coarctatus. Both C. coarctatus and C. sumatranus are considered to be members of the recently proposed section Coarctati (Coarctata), within the subgenus Chaetoceros. The taxonomic relationships of the two species is analyzed, and a formal Latin diagnosis of the section Coarctati is also given.     

Sticky predators: a comparative study of sticky glands in harpactorine assassin bugs (Insecta: Hemiptera: Reduviidae)

Zhang, G. and Weirauch, C. 2011. Sticky predators: a comparative study of sticky glands in harpactorine assassin bugs (Insecta: Hemiptera: Reduviidae). —Acta Zoologica (Stockholm) 00 : 1–10. For more than 50 years, specialized dermal glands that secrete sticky substances and specialized setae have been known from the legs of New World assassin bugs in the genus Zelus Fabricius (Reduviidae: Harpactorinae). The gland secretions and specialized ‘sundew setae’ are involved in enhancing predation success. We here refer to this predation strategy as ‘sticky trap predation’ and the specialized dermal glands as ‘sticky glands’. To determine how widespread sticky trap predation is among Reduviidae, we investigated taxonomic distribution of sticky glands and sundew setae using compound light microscopical and scanning electron microscopical techniques and sampling 67 species of Reduviidae that represent 50 genera of Harpactorini. We found sticky glands in 12 genera of Harpactorini and thus show that sticky trap predation is much more widespread than previously suspected. The sticky glands vary in shape, size and density, but are always located in a dorsolateral position on the fore tibia. Sundew setae are present in all taxa with sticky glands with the exception of Heza that instead possesses unique lamellate setae. The sticky trap predation taxa are restricted to the New World, suggesting a New World origin of this unique predation strategy.     

Unusual sensory setae of the raptorial Branchinecta gigas (Branchiopoda: Anostraca)

In many vernal pools, visibility is very poor because of the turbidity from suspended clay particles. For predatory species like Branchinecta gigas, these conditions can be detrimental to successful prey capture. In vernal lakes in central California, B. gigashave developed specialized hunting modes to capture anostracan prey in pools of low visibility. The position of their body, the kinematics of their locomotion, and their reduced eye size suggested the possibility of novel sensory structures on their antennae and/or their cercopods designed to enhance their prey capture abilities. Using Scanning Electron Microscopy, we investigated the presence and design of sensory setae on the antennae and cercopods of B. gigas. On both males and females, there are dense patches of sensilla along the length of the antennae. They are oriented ventrally and slightly anteriorly. These antennal setae appear to be chemosensory in structure and position; they resemble antennal setae of other branchiopods. However, the setae of the cercopods are unusual in their morphology and location on the appendage. The cercopods, which are bent over the head in the hunting position, have a linear arrangement of specialized setae on their ventral side. They are jointed setae with an anterior crown of protective spines. The setal joint only permits limited abduction either toward the head in the hunting position or ventrally when swimming. These setae appear to be mechanosensory in function and may be adaptations to a raptorial lifestyle. They correlate well with the behavioral components of hunting in B. gigasand their complex prey capture mechanism.     

BLOOMS OF SURF-ZONE DIATOMS ALONG THE COAST OF THE OLYMPIC PENINSULA,WASHINGTON. VI. DAILY PERIODICITY PHENOMENA ASSOCIATED WITH CHAETOCEROS ARMATUM IN ITS NATURAL HABITAT1,2

Microscope observations of chains of Chaetoceros T. armatum T. West, collected, from its natural habitat, at Copalis Beach, Washington, have been made. A regular daily periodicity in the occurrence of cell division stages and length of the chains was found on each occasion (November, February, April, May, August). During the night, short chains of 3 cells predominated. In early morning hours, average chain lengths increased due to cell elongation, and nuclear and protoplast division occurred. This correlated with the time of day when cell masses of C. armatum first appeared at the surface of the water. In the late afternoon, the new silica valves of the daughter protoplasts were formed. Formation of special bristle-bearing end valves effected the separation of long chains into shorter chains composed predominantly of 3 cells. (Cultured material was used to verify some of these stages.) This correlated with the time of day when cell masses disappeared from the water surface and dispersed.     

THE INLAND CHAETOCEROS (BACILLARIOPHYCEAE) SPECIES OF NORTH AMERICA1

Five taxa of Chaetoceros occur in inland waters of North America. These most commonly occur in waters with elevated total dissolved solids in arid regions of the western United States and Canada. Chaetoceros amanita Cleve-Euler is characterized by consistently forming relatively long chains of cells and having very spinose primary resting spore valves. Chaetoceros elmorei Boyer also forms long chains of cells which are connected by evident valvar processes; spores are nearly always smooth. Chaetoceros muelleri Lemm. may form short chains with processes between sibling valves, but also produces solitary cells lacking processes. Chaetoceros muelleri var. subsalsum (Lemm.)Johansen et Rushforth is similar to the nominate but never produces cells with Processes. Both of the C. muelleri varieties produce spores with smooth primary valves. Chaetoceros simplex Ostenfeld is characterized by a noncolonial habit, cells lacking processes and the production of resting spores with warty to some what spinose primary valves.     

A topographical and typological comparison of the rodlike setae of ambulatory dactylopodites in decapod crustaceans

The arrangement and external morphology of the rodlike setae and associated structures located on the dactylopodites of the walking legs of six species of decapod crustaceans are compared. The dactyls of littoral species, represented by the rock crab, Cancer antennarius, and the spiny lobster, Panulirus interruptus, have dense tufts and bands of rodlike setae, as is typical of many decapods, and additionally only a few small plumed setae. The arrangement of setae on the dactyls of the recently discovered Galapagos vent crab, Bythograea thermydron, closely resembles that of C. antennarius. Rodlike and long plumed setae occur in about equal numbers on the dactyls of the pelagic anomuran, Pleuroncodes planipes. The dactyls having the fewest rodlike setae are those of the terrestrial hermit crab, Coenobita perlatus, and those of the kelp crab, Pugettia producta, where flat setae typical of Majidae have replaced most rodlike setae. The presence and structures of the terminal pores in rodlike setae vary intra- and interspecifically, possibly as a function of molt stage. Variations in some features of rodlike setae, such as tip acuity and presence of microsetae and surface sculpting, appear to be related to development. Serrated setae occur on the dactyls of megalopal P. producta but not in later stages. The topography and typology of setae located on the ambulatory dactyls of decapod crustaceans are considered in light of recent interest in using setal characteristics to determine the sensory functions of sensilla and to clarify the phylogeny of arthropod groups.     

Protegulum and brephic shell of the earliest organophosphatic brachiopods

Early development stages imprinted on the shells of Cambrian brachiopods from the class Linguliformea (orders Paterinida, Lingulida, Acrotretida) were studied with scanning electron microscope based on a large collection from the Siberian Platform. Some specimens of all three orders preserved protegulum (embryonic shell); their brephic (juvenile) shells, also were studied. Many of them might lack larval development stage as it is known for the recent representatives of the family Lingulidae. But unlike recent lingulids, the surface of the juvenile dorsal valves of all studied linguliformeans bore two (rarely three) pairs of gentle elevations accommodating bundles of setae, which sometime preserve as groups of fine imprints along their margins. Recent Lingula and Glottidia lack setae in this stage. On the other hand, recent classes Craniformea and Rhynchonelliformea have setae, but they develop in the larval stage. Most of brachiopod groups have the setae in the adult stage but these setae have different origin, are short, located on the lateral and anterior ends of the shell, and grow from the marginal cells of the mantle.     

Diversity in the section Compressa of the genus Chaetoceros (Bacillariophyceae), with description of two new species from Chinese warm waters

Monoclonal strains of Chaetoceros species were collected from Chinese warm waters. Vegetative cells and resting spores were examined using light microscopy as well as scanning and transmission electron microscopy. Combined morphological and DNA sequence data from the hypervariable D1–D3 region of the nuclear ribosomal large subunit showed the presence of two new species within the section Compressa, herein described as Chaetoceros bifurcatus sp. nov. and C. millipedarius sp. nov. Both species possessed features typical of the section Compressa, but C. bifurcatus was characterized by the heavy intercalary setae fusing and extending together for a distance before diverging. The heavy setae were not visually contorted, lacking poroids and spines, in contrast with how the section Compressa has been defined. Chaetoceros millipedarius was characterized by a horizontal stagger of ordinary intercalary setae when the chain was seen in broad girdle view, making the chain look like a millipede. The two new species were supported by molecular phylogenetic analyses with C. bifurcatus sister to C. contortus var. ornatus, while C. millipedarius was sister to C. contortus var. contortus. Based on the morphological features exhibited in C. bifurcatus, the diagnosis of the section Compressa was emended to exclude “contorted” heavy setae and compressed valve faces.     

中国锈革菌属研究.5.采自云南的两个新记录种

报道了采自云南省的锈革菌属(Hymenochaete)2个中国新记录种,即长矛锈革菌(H. contiformis)和红边锈革菌(H. rufomarginata)。前者的主要特点是解剖结构中无皮层和菌丝层,刚毛长且孢子大; 后者的主要特点是子实层具大量的侧丝,刚毛和孢子较小。提供了这两个种的野外标本照片、显微结构绘图以及详细的形态学描述,并给出了云南省锈革菌属30个种的检索表。     

Sexual Morph of <i>Furcasterigmium furcatum</i> (Plectosphaerellaceae) from <i>Magnolia liliifera</i> Collected in Northern Thailand

We isolated an interesting fungus from dead leaves of Magnolia liliifera collected from Chiang Mai, Thailand. The novel strain is related to Plectosphaerellaceae based on the morphology of its asexual morph and the analysis of sequence data. Phylogenetic analyses using a combined gene analysis of LSU and ITS sequence data showed that this strain is clustered in the same clade with Furcasterigmium furcatum with high statistical support. The new strains produced the asexual morph in culture which is morphologically similar to F. furcatum. Thus, we identified this strain as the sexual morph of F. furcatum. This is the first record of sexual morph for the monotypic genus Furcasterigmium and the first record of this genus on Magnolia.     

Ostracod fauna of Duvensee,an ancient lake in Northern Germany

About 4000 ostracod valves have been analysed from a sediment core of a cultivated bog NW of Hamburg. The deepest deposits are sands free of subfossils, the uppermost layers consist of peat. In the sediment in between, there are three layers containing undestroyed valves. The ostracod assemblies of the older claygyttja (Late-glacial) and the two younger, fine detritus deposits (Post-glacial) are strikingly different. Cytherissa lacustris, Candona neglecta, Ilyocypris bradyi, Herpetocyrpis reptans, and two Limnocythere species were found in the Late-glacial layers. Changes in abundance of these species indicate alterations in climate, lake ground, water inflow and waterlevels. Postglacial layers are rich in Metacypris cordata valves associated with numerous Candona species, L. inopinata, Darwinula stevensi, and Cyclocypris laevis. These species are characteristic of a small lake with a large littoral zone. A similar development in ostracod assemblages is found in middle Europe by Absolon (1973), although the main Candona species is not C. neglecta but C. candida. Ostracod analysis cannot demonstrate an influence of anthropogenic impacts on ostracod successions.     

Structure of dactyl sensilla in the kelp crab,Pugettia producta

In the kelp crab, Pugettia producta, flat plate setae cover all but the ventral surfaces of the walking leg dactyls. Dendrites enter the setal shaft located inside the plate superstructure, and extend to a region of the setal tip that contains a system of minute pores resembling the pore systems found in chemosensory sensilla of insects. Presumably, much of the chemosensitivity of the dactyls in the kelp crab is mediated by the plate setae. In the interior of the dactyl, supporting cells and the neurons innervating plate setae, other types of setae, and other presumptive sensilla form scolopidia. Large scolopidia, containing as many as 12 dendrites, appear to innervate some of the plate setae and also large ventral rodlike setae that might be chemosensory. Two of the dendrites of large scolopidia usually have more densely packed microtubules, longer ciliary axonemes, slightly larger rootlets, and dark A fibers with arms, characteristics indicative of mechanosensory function. Some dactyl setae, therefore, could be both mechanosensory and chemosensory. Small scolopidia containing two or three dendrites that exhibit mechanosensory characteristics appear to innervate small, rodlike setae, which presumably are strictly mechanosensory. The two types of structures located on the epicuticular cap, elliptical structures resembling campaniform sensilla and small cones in pits resembling CAP organs, appear to be dually innervated and presumably are mechanosensory, although other functions are possible. The internal positions of the scolopidia, together with the support afforded by an extracellular dendritic sheath, by the scolopale, and by desmosomelike and septate junctions, may serve to protect internal portions of setal dendrites, some of which appear to remain functional in nonmolting adults that have abraded setae.     

A new species of Ilyocryptus (Anomopoda: Macrothricidae) from Argentina

I. elegans n.sp. from the Parana River, northeastern Argentina is proposed and its morphological features are compared with those of the apparently related I. agilis. Its outstanding characteristics are the long 2rd to 5th setae of ventral margin of the valves, the rudimentary nature of defensive setae, the low number of spines in the preanal lobe of postabdomen and the unequality of the length of the setae in the outer distal lobe of first trunk limbs.Finding of this new species suggests that I. agilis would be a complex of species and its records should be revised.     

Septins enforce morphogenetic events during sexual reproduction and contribute to virulence of Cryptococcus neoformans

Septins are conserved, cytoskeletal GTPases that contribute to cytokinesis, exocytosis, cell surface organization and vesicle fusion by mechanisms that are poorly understood. Roles of septins in morphogenesis and virulence of a human pathogen and basidiomycetous yeast Cryptococcus neoformans were investigated. In contrast to a well‐established paradigm in S. cerevisiae, Cdc3 and Cdc12 septin homologues are dispensable for growth in C. neoformans yeast cells at 24°C but are essential at 37°C. In a bilateral cross between septin mutants, cells fuse but the resulting hyphae exhibit morphological abnormalities, including lack of properly fused specialized clamp cells and failure to produce spores. Interestingly, post‐mating hyphae of the septin mutants have a defect in nuclear distribution. Thus, septins are essential for the development of spores, clamp cell fusion and also play a specific role in nuclear dynamics in hyphae. In the post‐mating hyphae the septins localize to discrete sites in clamp connections, to the septa and the bases of the initial emerging spores. Strains lacking CDC3 or CDC12 exhibit significantly reduced virulence in a Galleria mellonella model of infection. Thus, C. neoformans septins are vital to morphology of the hyphae and contribute to virulence.