Die Nesselkapseln der Anthozoen und ihre Bedeutung für die phylogenetische Systematik

Zusammenfassung 1. Phasen- und elektronenoptische Untersuchungen an Nesselkapseln von 35 Anthozoenarten aus Atlantik, Mittelmeer und Rotem Meer haben bei den einzelnen Klassen und Ordnungen eine große morphologische Divergenz der bisher gültigen Nesselkapseltypen (Weill 1934,Carlgren 1940) ergeben.Weills Nesselkapseltypen haben daher nur geringe taxonomische und phylogenetische Bedeutung.2. Atriche Haplonemen kommen nur bei den Ceriantharia und Actiniaria vor. Sie sind symplesiomorph.3. Die holotrichen Haplonemen weisen die größte Dornenmannigfaltigkeit auf. Die Dornen sind teilweise morphologisch wesentlich differenzierter als bei den rhabdoiden Heteronemen. Die meisten holotrichen Haplonemen sind auf Grund ihrer speziellen Dornenstruktur apomorphe Merkmale verschiedener Anthozoengruppen. Sie sind aber als Kategorie kein konstitutives Merkmal.4. Als symplesiomorphes Merkmal kommen bei zahlreichen Anthozoen am Schlauch verschiedener holotricher Haplonemen und am Faden verschiedener rhabdoider Heteronemen T-förmige Dornen vor. Spitze Dornen oder unbewaffnete Endfäden sind apomorphe Merkmale.5. Rhabdoide Heteronemen sind der einzige Nesselkapseltyp der Octocorallia, die sich wie die b- und p-Rhabdoiden der Hexacorallia in der Bewaffnung des Fadens unterscheiden.6. Auf Grund der vorliegenden Nesselkapselbefunde sind die Ceriantharia die ursprünglichsten Hexacorallia. Die Ceriantharia verfügen wie die ursprünglichen Actiniaria über die einfachsten Haplonemen und die am höchsten differenzierten Heteronemen.7. Actiniaria und Zoantharia sind in der Ausbildung anoploteler p-Rhabdoiden synapomorph mit einigen Ceriantharia.8. Die Zoantharia sind mit den Actiniaria in der Ausbildung völlig identischer p-Rhabdoiden (p-Rhabdoiden A) synapomorph.9. Als Schwestergruppe der Zoantharia sind die Antipatharia zu betrachten, die über weitgehend gleiche rhabdoide Heteronemen, mit Ausnahme einiger autapomorpher Typen, wie die Zoantharia verfügen.10. Die Nesselkapseln der Madreporaria (Scleractinia) und der Corallimorpharia stimmen mit Ausnahme einiger nur den Corallimorpharia eigenen spezieller Holotrichen in allen morphologischen Details vollständig überein. Die Nesselkapselbefunde beider Anthozoengruppen, die hier einheitlich als Madreporaria zusammengefaßt werden, haben dagegen nur wenige Hinweise auf verwandtschaftliche Beziehungen zu den Actiniaria ergeben. Die Ergebnisse werden in einer Stammbaumtabelle dargestellt.

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The nematocysts of the anthozoans and their importance for phylogenetical systematics

Nematocysts of 35 anthozoan species from Atlantic Ocean, Mediterranean Sea and Red Sea were studied employing phase contrast and electron microscopy. The nematocyst-types ofWeill's (1934) system exhibit a great divergence between different anthozoan orders. Therefore, they are of little taxonomic and phylogenetical value. Atrichous haplonemes occur in the Ceriantharia and in the Actiniaria; all other Hexacorallia have holotrichous haplonemes with very different spines. Sometimes they are morphologically much more differentiated than the spines of the rhabdoid heteronemes, the only nematocyst-type present in the Octocorallia. If their distal ends form a T, the spines are considered plesiomorphous; they are present on the tube of some holotrichous haplonemes as well as on the thread of some rhabdoid heteronemes.Carlgren's (1940) subdivision of the rhabdoid heteronemes is quite useful because the b- and p-rhabdoid differ in all orders of Hexacorallia by having a different armature on the thread. Ceriantharia are considered to represent the most plesiomorphous group among the Hexacorallia. They have the simplest haplonemes (tube atrichous ore with spines forming a T) and rhabdoids heteronemes with the most differentiated shaft, but feature plesiomorphous T-forming spines on the thread of the b-rhabdoids. In certain Ceriantharia, p-rhabdoids occur with a short anoplotelic thread which is synapomorphous in the Ceriantharia as well as in the Actiniaria and Zoantharia. The rather differentiated shaft is a symplesiomorphous character of the Ceriantharia and the early Actiniaria, which exhibit other symplesiomorphous characters, ectodermal longitudinal muscles in the scapus and the same swimming behaviour (Robson 1966). The Zoantharia are derived from the late Actiniaria. Plesiomorphous Zoantharia, like Endomyaria of the Actiniaria, possess large b-rhabdoids in their mesenterial filaments. In addition, all Zoantharia have exactly the same p-rhabdoids, common in the Endomyaria; p-rhabdoids differ only in the Antipatharia in that they have a somewhat longer thread, which are armed with single spines. The Endomyaria, as well as the Zoantharia and Antipatharia, are also synapomorphous in the main distribution of their b-rhabdoids and in having a special form of sperm. In addition, Antipatharia have the same normal b-rhabdoids as the Zoantharia and the same chemical composition of the skeleton as the skeleton-forming ZoanthariaGerardia savaglia, which differs markedly from the chemical composition of the gorgonian skeleton (Roche &Tixier-Durivault 1951).

     

The acanthodian<Emphasis Type="Italic">Machaeracanthus</Emphasis> from the Lower Devonian Hunsrück Slate of the Hunsrück region (Germany)

Two recently collected slabs from the Lower Devonian Hunsrück Slate of Bundenbach, Hunsrück region, Germany, with spines of the acanthodianMachaeracanthus hunsrueckianum n. sp. are described. Both are associations of large and small spines and are the first to show groupings of symmetrical pairs; the spines are not homologous with those of other acanthodians. A pair of small spines ofMachaeracanthus peracutus Newberry, 1857 from the Karschheck quarry near Oberkirn, Hunsrück region, Germany, is articulated with the pectoral girdle and is the first such complex to be described. The only spines whichMachaeracanthus appears to have had were a pair of large and small pectoral spines on each side of the body. These spines could have helped to prevent the fish from sinking into the mud while resting on the sea floor.     

NEMATOCYSTS OF THE SEA ANEMONE METRIDIUM

Six types of nematocysts and their nematocytes in tentaclesand acontia of the sea anemone Metridium senile fimbriatum werestudied by electron microscopy. Microbasic b-mastigophores, microbasic amastigophores, and basitrichshave one fundamental feature in common: a straight, complexly-foldedshaft with dense spines pointing apically. An additional resemblancebetween a b-mastigophore and a basitrich is the possession ofa long, narrow, coiled thread bearing spines. An amastigophoreis characterized by a short, looped, unspined thread and a cup-shapedgranular matrix. Atrich and holotrich nematocysts have a coiled, spined tubeof uniform diameter which lies in an evenly granular matrixfilling the entire capsule. The above five nematocysts have three flaps at the apex of thecapsule which open upon discharge, and each nematocyte possessesa flagellum with which is associated one or two centrioles anda striated rootlet. The long rootlet of the b-mastigophorebearingnematocyte passes through a circular band of fibrils surroundingthe neck region of the capsule, and the short rootlet of theatrich lies in a dense fibrous sheath surrounding all but theapex of the capsule. The spirocyst differs from the other nematocysts in having athin, ridged, singlewalled capsule; an inverted tube containingbundles of tubules; an apical disk covered only by a thin layerof granular material and the nematocyst membrane; and the absenceof a flagellum in its nematocyte. Theories of excitation and mechanism of discharge of nematocystsand the function of spirocysts are discussed in the light ofthis and other recent studies of the fine structure of nematocysts.Special attention is drawn to the probable role of the foldsin the walls of shaft and thread in increasing the length ofthe tube upon discharge.     

An atypical fauna in the Lower Devonian Hunsrück Slate of Germany

The Hunsrück Slate is a world renowned conservation lagerstätte, stretching SW-NE in a narrow band between the villages of Bundenbach and Gemünden, Hunsrück region, Germany. A great variety of complete Lower Devonian fossils is preserved with their soft parts pyritised due to rapid burial by sediment. The fossils of the Hunsrück Slate outside the narrow band are scarcely known. They represent the normal Situation: quiet low energy Sedimentation. This paper describes this overall “Rhenish” neritic fauna under the heading “atypical”, in contrast to the famous fossils of the conservation lagerstätte. The fauna described here lacks starfishes, mitrates and chelicerates. The paper begins with an overview of the recent relevant literature (stratigraphic position of the Hunsrück Slate, palaeoecology). The slate fossils were collected in two quarries WNW and NE of Bundenbach (Lingenbach and Karschheck, respectively) and most closely resemble that of the Wisper Valley in the Taunus region. Their geologic age is Lower Devonian, early Emsian, Ulmen Substage. Special interest is given to Community structures, rugose corals, bivalves, gastropods, trilobites, conulariids, brachiopods and crinoids. In the systematic part, the crinoidOrthocrinus simplex is redescribed. Also, two new species are introduced: the rugose coralVolgerophyllum karschheckensis n. gen., n. sp., and the crinoidAcanthocrinus spinosus n. sp.     

Tube foot preservation in the Devonian crinoid Codiacrinus from the Lower Devonian Hunsrück Slate,Germany

Fossilized tube feet are described on Codiacrinus schultzei Follmann from the Lower Devonian Hunsrück Slate of Germany. This is the first definitive proof of tube feet on any fossil crinoid. Three lightly pyritized, flattened tube feet are preserved in a single interray of this cladid crinoid. The tube feet were at least 7 mm long. Their preservation is very similar to the tube feet reported previously from a Hunsrück ophiuroid, except that the Codiacrinus tube feet have small papillae, similar to living crinoids.     

Preservation of tube feet in an ophiuroid (Echinodermata) from the Lower Devonian Hunsrück Slate of Germany and a redescription of<Emphasis Type="Italic">Bundenbachia beneckei</Emphasis> and<Emphasis Type="Italic">Palaeophiomyxa grandis</Emphasis>

The preservation of non-mineralized tissues in the fossil record is extremely rare. The Lower Devonian Hunsrück Slate of Germany has long been known for the preservation of non-mineralized tissues in pyrite but whether or not these remnants represent true soft tissues has been questioned. This is especially true for struetures visible only on radiographs that are too delicate for excavation by traditional methods. Here we report the discovery of well-preserved pyritized tube feet in six fully prepared specimens of the protasterid brittle starBundenbachia beneckei from the Hunsrück Slate. This discovery represents the first report of fossilized ophiuroid tube feet in the fossil record. The successful excavation of the delicate tube feet was made possible by improved airbrasive techniques developed by German fossil collectors. The relatively large size of the fossil tube feet inBunden-bachia beneckei is consistent with earlier inferences on size based on the presence of large podial basins. Protasterid ophiuroids lack the specialized arm musculature and articulations that provide increased flexibility and strength to the arms of modern ophiuroids with typically reduced tube feet. How-ever, tube foot form and perhaps function inBundenbachia might have been similar to those of living asteroids in which large tube feet are used primarily for locomotion and food-manipulation thus compensating for a lack of specialized arm musculature and articulation. Hence, feeding and life mode of protasterid ophiuroids was not necessarily limited to sedentary, infaunal microphagy as traditionally suggested. Two Hunsrück protasterid ophiuroids,Bundenbachia benecki andPalaeophiomyxa grandis are redescribed and compared.      

Cuticular structures of the stomodeum in Paulinia acuminata (De Geer) and Marellia remipes Uvarov (Orthoptera : Pauliniidae)

The cuticular lining of the stomodeum in orthopteroid insects usually bears cuticular structures, consisting of ridges, teeth, and spines, which are sometimes fairly complex. In some of these insects, particularly cockroaches and Orthoptera s. str., some of these structures have systematic value, mainly at the higher systematic levels. The cuticular lining of the stomodeum in Paulinia acuminata (De Geer) and Marellia remipes (Uvarov) (Orthoptera : Pauliniidae) (the only 2 genera included within the family) have been studied. Wide differences in the pattern of the stomodeal armature, and also in the shape, size and distribution of the spines in its different parts, are recorded. The proportions and limits of the crop and proventriculus, and the form and spatial distribution of spines and other characters, relative to the ridges, appear to be of taxonomic significance. They indicate that the 2 genera may not be closely related, as has been suggested, based on other evidence. While Marelliaappears to be related to the Acrididae, Pauliniaseems to be isolated from other acridoids, except for certain features in common with Proscopiidae and Eumastacidae.     

FLAGELLAR HAIRS IN PRASINOPHYTES (CHLOROPHYTA): ULTRASTRUCTURE AND DISTRIBUTION ON THE FLAGELLAR SURFACE1

The flagellar hair ultrastructure of 16 strains of species of the prasinophycean genera Mantoniella, Mamiella, Pseudoscourfieldia, Nephroselmis, Tetraselmis, Scherffelia, Pterosperma, and Pyraminonas was examined in detail by whole-mount electron microscopy. The flagellar hairs of all genera displayed a high degree of ultrastructural complexity that was completely conserved within each strain. In all strains, flagellar hairs occurred on the sides of the flagella (lateral hairs); in several strains, special flagellar hairs also were found on the flagellar tips (tip hairs; absent in the Chlorodendrales and in Nephroselmis). Two groups of lateral hairs were distinguished: 1) T-hairs (“Tetraselmis-type” flagellar hairs), characterized by a smooth, tubular shaft of ca. 15 nm diameter and an overall length of 0.5–1.3 μm, and 2) P_t-hairs (“Pterosperma-type lateral flagellar hairs”), which were considerably longer (ca. 1.5–5.4 μm), characterized by a thick shaft of ca. 30 nm diameter, which was covered with a layer of regularly spaced small particles of ca. 10 nm diameter. In both groups of flagellar hairs, a strain-specific number of subunits (1–101) in linear arrangement was attached to the distal end of the shaft. Tip hairs were either structurally related to T-hairs (Mamiellales, Pseudoscourfieldia) or represented a separate group, P_t-hairs (“Pterosperma-type flagellar tip hairs”; Pterosperma, Pyramimonas). In four genera (Mantoniella, Mamiella, Pseudoscourfieldia, Nephroselmis), both groups of lateral hairs occurred together on the same cell. Interestingly in these taxa the P_t-hairs were exclusively attached to the shorter immature flagella (no. 2), but, in contrast, in Mantoniella and Pseudoscourfieldia the tip hairs were restricted to the longer mature flagellum (no. 1). Thus, flagella of different developmental status differ in their hair-scale complement. The occurrence, distribution, and ultrastructure of flagellar hairs can be used to identify and classify prasinophytes at all taxonomic levels.     

The torus semicircularis in a gekkonid lizard

The cytoarchitecture and neuromorphology of the torus semicircularis in the tokay gecko, Gekko gecko, were examined in Nissl-stained, fiber-stained, and Golgi-impregnated tissues. From a superficial position, the torus semicircularis extends rostrally under the caudal half of the optic tectum. Caudally, the two tori abut upon one another; rostrally, they diverge. The torus semicircularis consists of central, laminar, and superficial nuclei. The central nucleus consists of fusiform, spherical and triangular neurons. Their dendrites are highly branched, with numerous dendritic spines, and are oriented mediolaterally, dorsoventrally, and rostrocaudally. Fusiform and spherical neurons display two dendritic patterns: “single axis,” ramifying in one axis, and “dual axis,” exhibiting higher-order branches perpendicular to the primary dendrites. Triangular neurons exhibit a “radiate” dendritic pattern. In the rostral half of the torus semicircularis, the laminar nucleus caps the central nucleus. The laminar nucleus encircles the central nucleus in the caudal torus semicircularis. The neurons of the laminar nucleus have dendritic arrays oriented parallel to the border of the central nucleus. These dendrites exhibit a paucity of dendritic spines and higher-order branches. Fusiform and spherical neurons exhibit “single axis” and “dual axis” dendritic patterns. Triangular neurons display “radiate” patterns. The caudal superficial nucleus lies dorsal and dorsolateral to the central nucleus. The superficial nucleus is sparsely populated by small fusiform and spherical neurons with moderately branched dendrites and moderate numbers of dendritic spines. These neurons display “single axis” (fusiform neurons) as well as “dual axis” and “radiate” (spherical neurons) dendritic patterns. They are oriented either parallel to or perpendicular to the boundary of the laminar nucleus.     

A handy impact corer for sampling lake surface sediment

A handy impact corer for sampling of surface sediment (< 50 cm) in lakes is described. The coring apparatus consists of a sample tube, tube holder, stopper, stopper holder, shaft with wing, shaft holder, hammer, and pushing rod. The total weights are 3.8 kg (Type I: 2.3 cm inside diameter of the tube) and 6.7 kg (Type II: 5.5 cm inside diameter of the tube). The system enables confirmation of the vertical landing of the corer onto the lake bottom and effective entering of sediment into the sample tube using hammer, and prevention of falling out of the core using stopper and pushing rod.     

A tubicolous animal from the Hunsrück Slate (Lower Devonian,Southern Germany)

A small tube-dwelling organism is interpreted as living in the sediment. This life habit is inferred from the difference between lined burrows and tubes and between soft and rigid tubes. Lamellar extensions of the body-wall may have provided irrigation for the vermiform part of the body. The gaping aperture lacks an operculum and may have been open permanently; the apertural rim was strengthened by spicules. The specimen lacks segmentation and is thus not an annelid worm. Considering the theoretical suitability of the crinoid “forest” in the Hunsrück sea for such worms, the absence of Annelida is curious.     

Spine skeleton morphogenesis during regeneration in clypeasteroid and camarodont sea urchins

The process of skeleton morphogenesis is described for broken and totally removed spines in clypeasteroid (hollow spine) and camarodont (solid spine) sea urchins. Spine regeneration after total spine removal is completed in 40–45 days in clypeasteroids and in 60–70 days in camarodont sea urchins. Along with common stages of formation of longitudinal ribs in both hollow and solid spines, fundamental differences were found between the initial stages of reparative growth of the spine shaft. The spine shaft is formed from a single median process in clypeasteroids and from many simultaneously growing processes in camarodont sea urchins. Reparative morphogenesis of totally removed and partly broken spines in clypeasteroid sea urchins and totally removed spines in camarodont sea urchins leads to the formation of a skeletal structure identical to the intact spine. However, during the regeneration of broken camarodont spines, lateral growth is markedly retarded. As a result, the regenerated part of the spine shaft has a smaller diameter when the initial spine length is achieved. A hypothesis is proposed on a paedomorphic origin of spines in the clypeasteroid sea urchins on the basis of the juvenile stage of definitive spines in the camarodont sea urchins.     

Fine structure of the dorsal bristle complex and pellicle of Euplotes

The fine structure of the dorsal bristle complex and pellicle of non-developing Euplotes eurystomus is described in detail by scanning and transmission electron microscopy. The bristle-pit unit is a highly differentiated complex of organelles. The bristle complex is composed of a pair of kinetosomes (basal bodies) joined by a connective. The anterior kinetosome bears the bristle cilium, which contains a polarized network of particles (“lasiosomes”). The posterior kinetosome bears a very short, knob-like “condylocilium,” and has an associated striated fiber. Accessory ribbons of microtubules are also associated with the kinetosome couplets. Parasomal sacs, a septum connecting the bristle cilium to the anterior wall of the pit, core granules of the kinetosomes, and large membranous ampules are described. The organization of the bristle complex bears many similarities to the somatic ciliature of other ciliates. The pellicle of Euplotes is composed of a continucus outer cell membrane subtended by membranous alveoli, which contain a “fibrous mat.” Two sheets of subpellicular microtubules (longitudinal and transverse) are located just beneath the alveoli. The “epiplasm” seen in some other ciliates is apparently absent in Euplotes. The texture of the cell surface is a pattern of folds or rugae composed of the outer cell membrane and the upper membrane of the alveolus. The pattern of rugae probably defines the “silverline-system” of light microscopy.     

Interpretation and Application of Article 298 of the Law of the Sea Convention in Recent Annex VII Arbitrations: An Appraisal

Article 298 of the UN Convention on the Law of the Sea allows state parties to exclude certain categories of disputes from the compulsory procedures entailing binding decisions. This provision serves as a “safety valve” by excluding sensitive issues mainly related to sovereignty. This article examines the three recent Annex VII Arbitral Awards (the South China Sea Arbitration; the Arctic Sunrise Arbitration; and the Chagos Marine Protected Area Arbitration) that assessed the interpretation and application of Article 298.     

Specialized cilia of the byssus attachment plaque forming region in Mytilus californianus

The distal depression of the ventral pedal groove of Mytilus californianus was investigated by scanning and transmission electron microscopy. This part of the byssus forming system is responsible for the formation of the attachment plaque of the byssus thread. The longitudinal pedal ducts open into this area and the floor of the distal depression is covered by specialized cilia which terminate as biconcave flattened discs or “paddles.” The disc is formed by a 360° curvature of the axoneme tip within the ciliary membrane. The diameter of the disc is about 1.33 μ while that of the shaft portion is 0.24 μ. There are about 11 cilia per square micron of surface area and the necks of the cilia are separated from each other by a web-like extension of apical cytoplasm extending from the epithelial cells. It is proposed that these specialized cilia function as microscopic spatulas for the application of the adhesive plaque material to substrate surfaces. The pattern of surface convection currents seen in vivo tends to support this hypothesis.     

Seabirds and marine mammals in the eastern Barents Sea: late summer at-sea distribution and calculated food intake

The at-sea distribution of seabirds and marine mammals in the eastern Barents Sea was determined using standardized transect counts during three cruises of RV“Dalnie Zelentsy” (Murmansk) in late summer 1991, 1992 and 1993. Totals of 32,268 seabirds, 485 pinnipeds, 25 cetaceans and 4 polar bears were counted during 554 half-hour counts. Numbers were converted into densities, total biomass and calculated daily food intake. Mean total food intake in kg fresh weight/km².day was 3.1 for the entire zone and all years; fish eaters dominated the whole region, with an intake of 1.3 (mainly Brünnich’s guillemot, Uria lomvia, and harp seal, Phoca groenlandica), followed by zooplankton eaters (0.85, mainly fulmar, Fulmarus glacialis) and mixed zooplankton and fish feeders (0.75, mainly minke whale, Balaenoptera acutorostrata, and kittiwake, Rissa tridactyla). Year-to-year variations were of little importance, while geographic differences were obvious between Norwegian coastal, Atlantic and Barents Sea water masses, both quantitatively and qualitatively (relative importance of main diets). Within each zone, a strong geographic heterogeneity was noted, with high local concentrations at fronts between water masses and at ice edges.     

FURTHER OBSERVATIONS AND SOME COMMENTS ON THE FINE STRUCTURE OF THE CENTRIC DIATOM AULACOSEIRA ISLANDICA (BACILLARIOPHYCEAE)1

Using light and electron microscopy, the diatom species Aulacoseira islandica (O. Müll.) Sim. was examined with special emphasis on the following characteristics: structure of the valve areolae, heterovalvy, and distribution of the rimoportulae. The mantle and valve face areolae were pores containing volate occlusions. However, observations only using transmission electron microscopy may result in an incomplete interpretation because of the fragility of the dissected system of volae. Relief valves with a stepped mantle and intaglio valves with a plain mantle occurred. Another form of heterovalvy resulted from the formation of separation valves. Linking valves had spatulate spines while separation valves bore tapering spines. In Aulacoseira, the rimoportulae usually occurred near the “Ringleiste.” The presence of several rimoportulae on the mantle was one of the most striking features in Aulacoseira islandica.     

First record of eurypterids (Chelicerata,Eurypterida) from the Lower Devonian (Lower Emsian) Hunsrück Slate (SW Germany)

For the first time, fossils of unquestionable eurypterid origin are documented from the renowned Lower Devonian Hunsrück Slate Lagerstätte in southwestern Germany. The gnathobase of a coxal plate and a body segment can be attributed to pterygotid eurypterids, probably to Jaekelopterus rhenaniae. These body parts from the Hunsrück Slate once more confirm the extraordinary large size that could be attained by this Rhenish eurypterid. Based on the usual occurrence in marine–terrestrial transitional facies elsewhere in the Rhenish Devonian, rareness in the Hunsrück Slate, and poor preservation, the Hunsrück Slate pterygotid remains are most probably allochthonous, and eurypterids are considered nongenuine elements of the ‘Hunsrück Slate biota.