Die Bildung und Differenzierung des postnauplialen Keimstreifs vonDiastylis rathkei (Crustacea,Cumacea)

Zusammenfassung Die Differenzierung der hinter den Mandibeln gebildeten ektodermalen Querreihen des Keimstreifs vonDiastylis wird beschrieben. 4 dieser Querreihen von Zellen werden nicht durch Ektoteloblasten gebildet, sondern lagern sich direkt als Blastodermzellen aneinander. Dahinter werden 12 Reihen durch Ektoteloblasten gebildet. Die Ektoteloblasten teilen sich zum Schlu\ in die Reihen XIII und XIV. Alle Zellreihen treten in eine Folge von differentiellen Teilungen ein, so da\ die genaue Differenzierung und Musterbildung der Zellen bis zur Bildung von Ganglienanlagen und ExtremitÄtenknospen zellgenealogisch verfolgt werden kann. Die ersten 2 Reihen hinter den Mandibeln, die Reihen (0) und (1), tragen zur Bildung des vorderen und mittleren Teils des 1. Maxillensegments bei. Der hintere Teil des 1. Maxillensegments wird durch die vorderen Zellabkömmlinge der Reihe (2) gebildet. Die 1. Maxille ist aus Zellen von verschiedenen Zellklonen zusammengesetzt, die zur Reihe (1) und (2) gehören. Die 2. Maxille und die Thorakalbeine werden ebenfalls durch verschiedene Zellklone zusammengesetzt.Die Reihen (2) und (3) haben ein Ähnliches Differenzierungsmuster. Die Unterschiede betreffen hauptsÄchlich den extremitÄtenbildenden Bereich. Die Reihe (3) und die erste ektoteloblastisch gebildete Reihe I sowie die folgenden extremitÄtenbildenden Reihen sind in ihrer Differenzierung fast identisch. Die Ganglien bilden sich durch Neuroblasten, welche Ganglienmutterzellen ins Innere abgeben. Die Neuroblasten haben ein kompliziertes Teilungsmuster. Sie können sich auch nach Abgabe von Ganglienmutterzellen Äqual teilen. Die Intersegmentalfurchen laufen schrÄg durch die Abkömmlinge einer Reihe und markieren nicht die genealogischen Grenzen.Die Ergebnisse werden im Vergleich mit anderen Mandibulaten, besonders mit den Insekten diskutiert. Es ergeben sich interessante Ähnlichkeiten und Unterschiede in der Bildung eines morphologischen Differenzierungszentrums und in der Anlage von ExtremitÄtenknospen, von Ganglien und Intersegmentalfurchen.

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Formation and differentiation of the post-naupliar germ bandm Diastylis rathkei (crustacea, cumacea)II. Differentiation and pattern formation of the ectoderm

Summary The differentiation of ectodermal cell rows arranged on the germ band ofDiastylis behind the presumptive mandibular segment is described. 4 of the cell rows are not budded off from ectoteloblasts, but are formed directly by blastoderm cells. Behind these 4 rows, 12 cell rows are budded off from ectoteloblasts. Eventually, the ectoteloblasts divide to form rows XIII and XIV. All of these cell rows have a fixed sequence of mitoses by which a detailed analysis of the cell-lineage up to the formation of ganglion anlagen and appendage buds is possible. The rows (0) and (1) form the anterior and middle parts of the maxillular segment. The posterior part of this segment is formed by derivatives of the subsequent cell row (2). Thus, the maxillulae are complex structures, composed by cells from different cell clones. The maxillae and the thoracic limbs are complex structures as well. Rows (2) and (3) have a similar differentiation pattern. The differences are mainly found in the appendage-forming parts. The differentiation of row (3) is nearly identical to row I, i.e. the first row budded off from ectoteloblasts, and to the subsequent rows II–VI.Ganglion cells are formed by the division of ganglion mother cells that are budded off from neuroblasts. The neuroblasts have a complicated pattern of divisions. There may be an alternation of unequal and equal mitoses. The intersegmental furrows run in a transverse and slightly oblique plane through the derivatives of one cell row. They do not indicate genealogical boundaries.The results are compared with similar developmental processes in other Mandibulata, especially Insecta. The similarities and differences in the existence of a morphological differentiation center and in the formation of appendage buds, ganglion anlagen, and intersegmental furrows are discussed.

     

Molecular insights into Cumacean family relationships (Crustacea, Cumacea)

Cumaceans are a diverse order of small, benthic marine crustaceans. Phylogenetic hypotheses for the eight currently recognized cumacean families have not been formally proposed. However, based on external morphological traits and Linnean classification, a few conflicting hypotheses of relatedness have been proposed. Family definitions rely on morphological characters that often overlap and diagnoses are based on a combination of non-unique characters. Morphological analysis does not provide a well-resolved phylogeny. In the present study, we use amino acid sequences from the mitochondrial cytochrome oxidase I gene to produce a molecular phylogenetic hypothesis for the families of Cumacea. Phylogenetic analyses at the amino acid level were performed under Bayesian, likelihood, and parsimony methods. Results strongly suggest that families lacking an articulated telson form a monophyletic group. This pleotelson clade, composed of the families Bodotriidae, Leuconidae, and Nannastacidae, is the most derived within the Cumacea. Within this group, the Bodotriidae resolve paraphyletically, with Leuconidae and Nannastacidae embedded within it. Comparison of the molecular phylogeny with that based on morphology suggests that many "diagnostic" characters are homoplasious.     

Elektronenoptische Untersuchungen des Darmtraktes und der peritrophischen Membran von Cladoceren und Conchostracen (Phyllopoda,Crustacea)

Zusammenfassung Vorder- und Mitteldarmtrakt, sowie peritrophische Membranen (PM) vonDaphnia pulex Leydig,Daphnia magna Straus,Leptestheria dahalacensis Rüppell und deren Nauplien wurden elektronenoptisch untersucht. Die Trichtermündung des Vorderdarmes ist bei Leptestherien mit reusenartig in das Mitteldarmlumen ragenden Borsten versehen. Bei Zellen, die eine geringere Elektronendichte als der Mitteldarmzellgrundtyp aufweisen, handelt es sich wahrscheinlich um jugendliche Zellen. Andere Zellen mit geringer Elektronendichte und jeweils zwei freien Cilien kommen nur bei Leptestherien vor. Die PM setzt sich aus dem in den Mikrofibrillen lokalisierten Chitin und aus einer Grundsubstanz zusammen, die vorwiegend aus Mucopolysacchariden und Proteinen besteht. An der PM-Bildung sind alle Mitteldarmzellen beteiligt. Die Einzelfibrillen entstehen möglicherweise durch als OberflÄchenkatalysatoren wirkende Enzyme und sind bei allen Arten in Streuungstextur und Wabentextur mit lumenseitiger Streuungstextur-Unterlagerung angeordnet. BeiL. dahalacensis sind zusÄtzlich Gittertexturen ausgebildet. Wahrscheinlich entstehen aus gestreut verlaufenden, noch plastischen Mikrofibrillen durch überformung an Mikrovilli in Reihe die Gitter- und durch überformung an Mikrovilli in Reihe und auf Lücke die Wabentexturen. Netzmuster können offenbar auch durch sekundÄre Zusammenlagerungen von bereits primÄr ringförmig um die Mikrovillispitzen gebildetes PM-Material entstehen. Bei fehlender Darmfüllung werden zudem bei Leptestherien weder hochgeordnete Fibrillenmuster, noch PM-Hüllen ausgebildet. Das Mitteldarmlumen ist dagegen mit einem Mikrofibrillenfilz ausgefüllt.

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Electron-mikroscope study of the gut and of the peritrophic membrane in cladocera and conchostraca (Phyllopoda, crustacea)

Summary Foregut, midgut and peritrophic membrane (PM) ofDaphnia pulex Leydig,Daphnia magna Straus andLeptestheria dahalacensis Rüppell were studied with the electron microscope. The tubeshaped foregut ofL. dahalacensis has bristles, which rise up trap-like into the lumen of the midgut. Cells with a lower electron density than most of the other midgut cells are probably juvenile cells. Other cells with a lower electron density each with two free cilia, are only to be found inL. dahalacensis. The PM is composed of chitin localised in microfibrils and of another basic substance consisting mainly of protein and mucopolysaccharides which serve as a matrix. All of the midgut cells participate in the formation of the PM. The microfibrils are possibly formed by enzymes acting as surface catalysts. The microfibrils of all Phyllopoda are either arranged in arbitrary directions or in hexagonal networks which always seem to be accompanied by the random type. PMs ofL. dahalacensis can have in addition an orthogonal orientation of fibrils. Perhaps by transformation of arbitrarily arranged, still plastic fibrils at cell surfaces, where microvilli are arranged in rows, an orthogonal texture results, and where the microvilli are arranged in staggered rows, honeycomblike textures are formed. It may be that these patterns also arise through the secondary assemblage of PM-material which was initially arranged in a cyclic fashion around the microvilli-tips. When the intestinal tract is empty, inL. dahalacensis neither highlyordered patterns of fibrils nor PM are formed. Instead, the midgut lumen is filled up with a compressed, disordered mass of microfibrils.

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Liste der Abkürzungen B Basalmembran - Cu Cuticula - CZ Zelle mit Cilien - eM elektronendichtes Material - H hexagonale Fibrillenmuster - M Mitochondrien - Mv Mikrovilli - N Nucleus - PM peritrophische Membran - R PM-Material in Ringform - tw terminal web Gekürzte Fassung einer von der FakultÄt für Bio- und Geowissenschaften der UniversitÄt Karlsruhe genehmigten Dissertation (Schlecht, 1978)     

Die organogenetische und transitorische rolle der vitellophagen in der darmentwicklung von Galathea (Crustacea,Anomura)

The present study of the development of the different organs of the gut, the vitellophags (primary yolk cells) and the other cell-types concerned with the resorption of the yolk gives the first detailed analysis of an Anomuran development.

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Verzeichnis der Abkürzungen in den Abbilduugen A ₁ 1. Antenne - A ₂ 2. Antenne - Ab Abdomen - Au Auge - B Blastoderm - Bb Blastodermbildung - Bl Blutlakunensystem - Bm Blastomer (Furchungszelle) - Bp Blastoporus - BZ Blutzelle - Ca Cardiamagen - Cf Carapaxfalte - Cp Caudalpapille - DI Drüsenfilter (Magen) - zDk zentraler Dotterkörper - Do Dorsalorgan - pDp primare Dotterpyramide - tDp tertiare Dotterpyramide (Vitellophagenepithel) - DR Rest des intraembryonalen Dottersackes - ieDS intraembryonaler Dottersack - bDv blastodermale Dottervakuole - sDZ sekunddre Dotterzelle - tDZ tertiare Dotterzelle - sE sekunddre Epithelialisierung (der Vitellophagen) - Ec Ectoderm - Ed Enddarm - Eh Eihiille (Chorion) - Ep Entodermplatte - Et Entodermtrichter - Ex Extremitdt (bsw. Extremitätenanlage) - Fsp Furchungsspindel (Teilungsspindel) - H Herz - ID Innendotter - Im Immigration (des Mesentoderms) - In Invagination (des Mesentoderms) - Ke Kern - KL Kopflappen (optischer Lobus) - KM Kaumuskulatur - L Darmlumen - M Mitose - Ma Magen - Md Mitteldarm - dMd dorsaler Mitteldarmdivertikel (dorsaler Mitteldarmblindsack) - Me Mesoderm - McEn Mesentoderm - Mddr Mitteldarmdrüse - Ml Mandibel - Mp ₁ 1. Maxilliped (1. Kieferfuß) - Mp ₂ 2. Maxilliped (2. Kieferfuß) - Mp ₃ 3. Maxilliped (3. Kieferfuß) - Mu Muskulatur - M₁ 1. Maxille - M₂ 2. Maxille - N Ganglien des Nervensystems - Ni Niere (Antennendrüse) - Oe Oesophagus - Ol Oberlippe - Pl Plasma - Py Pylorusmagen - Qv Querverbindung zwischen den Kopflappen - pR perivitelliner Raum - Seg Segment - Sf Sternalfurche - Sto Stomodaeum (Anlage des Vorderdarmes) - TA Thoracoabdominalanlage - Te Telson - Ul Urdarmlumen - V Vitellophage (primare Dotterzelle) - V ₁ Vitellophage 1 (1. Vitellophagengeneration) - V ₂ Vitellophage 2 (2. Vitellophagengeneration) - dV degenerierende Vitellophage - V intravitelline Vitellophage - IV Initialvitellophage (Lumenbildung) - pV perivitelline Vitellophage - Va Vakuole - Vi gelöster Dotter (im Darmlumen) - fZ freie Zellen (im perivitellinen Raum) Ausgeführt mit Mitteln des Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung and der Freiwillig Akademischen Gesellschaft der Stadt Basel.     

Systematics of the genera of Bodotriidae (Crustacea: Cumacea)

The cumacean family Bodotriidae includes 382 species in 31 genera grouped in three subfamilies: Bodotriinae, Mancocumatinae and Vaunthompsoniinae. Generic diagnoses are based on few characters that often have overlapping states among genera, complicating the understanding of the relationships within the group. The goals of this study are to illuminate the phylogenetic relationships among the genera of the Bodotriidae using morphological characters and to review the systematics of the family. For this purpose, all species within each genus were studied from the literature to code all the variability of genera for 109 variable morphological characters. Phylogenetic analyses show that there is independent reduction of the pleopods in two clades from a plesiomorphic state of five pairs, while the number of exopods of peraeopods has been reduced gradually in more derived groups of bodotriids. The subfamily Bodotriinae is the most derived and the Vaunthompsoniinae the most basal, and is paraphyletic with the Mancocumatinae embedded within it. No discriminatory characters were found between the subfamilies Mancocumatinae and Vaunthompsoniinae and they are not clearly separated in the phylogeny. Mancocumatinae is synonymized with Vaunthompsoniinae and all the genera of the former Mancocumatinae should be included within Vaunthompsoniinae. Analyses of character evolution justify a few other taxonomic changes. All genera were redescribed based on all the coded characters and a complete list of all valid species for each genus is included. Finally, dichotomous keys for identification to genus level are provided.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 , 1–58.     

Deep-sea Bodotriidae (Crustacea: Cumacea) from New Caledonia, Fiji and Indonesia

Cumaceans (Crustacea: Peracarida) belonging to the family Bodotriidae collected between 206 and 3680 m depth, during the French campaigns BIOCAL and BIOGEOCAL in waters of New Caledonia, KARUBAR in Indonesia and BORDAU 1 around Fiji were studied. The 93 specimens belonging to this family were assigned to 11 species, ten of them new to science, namely Cyclaspis variosculpta sp. nov., Cyclaspis richeri sp. nov., Cyclaspis dictyota sp. nov., Cyclaspis decora sp. nov., Cyclaspis magna sp. nov., Cyclaspoides erugatus sp. nov., Alticuma? ectyphum sp. nov., Apocuma pacificum sp. nov., Hypocuma fragosum sp. nov. and Bathycuma coremium sp. nov. The genera Cyclaspoides and Hypocuma are recorded for the first time from the Pacific Ocean. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 152 , 227–254.     

Die embryonalentwicklung des kopfes und prothorax von Carausius morosus br. (Insecta,Phasmida)

The development of the head — especially of the head structures which show traces of a metameric origin — is described. These structures confirm that the head of Carausius consists of an acron and six segments. The development of the thorax and legs confirm Weber's subcoxal theory.     

Die Calyptopis- und Furcilia-Stadien vonEuphausia hanseni (Crustacea: Euphausiacea)

The larval development is discussed and calyptopis stages I–III as well as furcilia stages I–VII are described. The larval development is similar to that ofE. spinifera, E. longirostris andE. triacantha (group d of genusEuphausia). Antennule, antenna, mandible, maxillule, maxilla and spines on the telson are unsuitable for identifying the larvae of different species of the genusEuphausia. The following characteristics can be used to distinguish the different larvae: form and marginal spines of the carapace, form of the rostrum, spines on the segments of the abdomen, and number and form of the pleopods. The mandible of larval Euphausiacea produces an asymmetric lacinia mobilis and a pair of processus incisivus accessorius (spine row). These two appendages are lacking in adult Eucarida.

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Mitglied der Taxonomischen Arbeitsgruppe an der Biologischen Anstalt Helgoland     

Die Entwicklung und Wandlung des Zusammenlebens von Pilzen und Algen

Ohne Zusammenfassung     

Morphologie und Funktion des Wasserleitungssystems der terrestrischen Isopoden (Crustacea,Isopoda, Oniscoidea)

Zusammenfassung 1. Das Wasserleitungssystem der Oniscoidea wird einer Strukturanalyse unterzogen. Die Teilstrukturen des Systems werden dargestellt. Es wird gezeigt, daß das System seinen Anfang an der Harnöffnung des Cephalothorax nimmt, wo es den aus den Maxillarnephridien stammenden Harn aufnimmt und durch ventrale und dorsale Leitungsstrukturen zum Pleoventralraum leitet. Aus diesem wird der Harn durch den Anus wieder aufgenommen und vom Rectum resorbiert.2. In der Strukturanalyse wird gezeigt, daß innerhalb der Oniscoidea zwei Typen des Wasserleitungssystems unterschieden werden können: der Porcellio-Typ und der Ligia-Typ. Bei grundsätzlicher Gleichheit beider Typen bestehen folgende Unterschiede: der Ligia-Typ hat an den 6. und 7. Pereiopoden Leitungsstrukturen, mit denen Wasser aufgesaugt wird. Im Wasserleitungssystem des Ligia-Typs fließt Harn und Wasser, in dem des Porcellio-Typs nur Harn.3. Da die entwicklungsgeschichtlichen Extreme Ligia und Hemilepistus ein Wasserleitungssystem haben, bei 45 weiteren Arten verschiedener Familien keine Assel ohne ein solches System gefunden werden konnte, muß geschlossen werden, daß dieses System konstitutiv für alle Landasseln ist. Alle untersuchten Arten lassen sich einem der beiden System-Typen zuordnen.4. Die vorgefundenen Strukturen werden auf ihre Funktion hin interpretiert. Es wird die Hypothese vertreten, daß das Wasserleitungssystem ein geschlossenes (Porcellio-Typ), multifunktionales System, vor allem aber integraler Bestandteil des Exkretionssystems ist. Das bei der Ammoniotelie auch terrestrischer Isopoden anfallende NH₃ wird im Harn aus dem Körper entfernt. Aus dem Harn entweicht das NH₃ wegen der enormen Oberflächenvergrößerung der Harnflüssigkeit beim Durchfluß durch die Leitungsstrukturen des Wasserleitungssystems. Der Harn selber wird nach Durchfließen des Pleoventralraumes durch die Endopodite und durch den Anus in den Körper wieder aufgenommen.Der Nachteil der Ammoniotelie, der hohe Wasserbedarf, wird so aufgehoben und der Vorteil, die Energieersparnis, gewahrt. Darüber hinaus gehört das System zu den Funktionskreisen Respiration und Thermoregulation und hat außerdem Funktionen bei der Wasserleitung sowie bei der Feuchthaltung und Reinigung des Integuments.5. Das Wasserleitungssystem wird als im Tierreich einzigartiger Weg erwiesen, die physiologischen Probleme des Landganges zu bewältigen.

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Morphology and function of the water conducting system in terrestrial isopods (Crustacea, Isopoda, Oniscoidea)

Summary In terrestrial isopods there are two types of a water conducting system. The porcellio-type is a recycling system. Out of the maxillar-nephridium urine is secreted, which spreads through the ventral and dorsal structures of the water conducting system. It is then directed along the pleopods and is reabsorbed in the gut. Within this system only urine runs. The ligiatype is an open system. Here urine runs as well as water, which is absorbed by the sixth and seventh pereiopods.In all the species investigated incl. Ligia and Hemilepistus a water conducting system has been found. Apparently this system is constitutive for all terrestrial isopods. Concerning function (hypothesis): the water conducting system is multifunctional, but above all serving excretion. Isopods, also terrestrial isopods, are ammoniotelic. While the urine is spreading through the conducting structures ammonia is vapourizing off the increased surface. A special permeability of the integument needs not be assumed. After the urine having passed the anus, it is reabsorbed in the gut. The disadvantage of the ammoniotelism, the great demand of water, is avoided, the advantage, the economizing of energy, is preserved.Additionally the water conducting system allows an active thermoregulation to a certain extent. Furthermore it has functions in respiration, conducting of water and keeping the integument humid and clean.

     

Leucon parasiphonatus,a new species (Crustacea: Cumacea: Leuconidae) from Antarctic waters

Six specimens ofLeucon parasiphonatus n. sp. were collected at depths ranging from 15 to 424 m in the vicinity of King George Island (South Shetland Islands, Antarctica) and the south eastern Weddell Sea.Leucon parasiphonatus belongs to the subgenusLeucon and differs from the other already known antarctic and Subantarctic species of the genus, in the absence of a serrated dorsomedian line and in the presence of a long pseudorostrum with several fine setae at its tip, surrounding the very long branchial siphon. The surface of the carapace is granulated; the carapace displays no teeth except for a few at its antero-lateral margin and at its ventral margin. The species most similar toLeucon parasiphonatus isLeucon siphonatus, reported from Mediterranean and North Atlantic waters.     

Morphology and Differentiation of Non-sensory Cuticular Structures in Mysidacea, Cumacea and Tanaidacea (Crustacea, Peracarida)

The non-sensory cuticular structures of some peracarideans (Mysidacea, Cumacea, Tanaidacea) were examined by scanning electron microscopy. The various types of structures present in the adult specimens are listed and the relation amongst them is elucidated. Three ways of differentiation of the structures can be distinguished: 1) a differentiation in the complexity of the structures themselves, 2) a differentiation of their arrangement on the body. 3) a differentiation of their distribution on the various parts of the body. A highly differentiated type of arrangement (row) of a number of simple structures (e.g. teeth) may lead to a higher complex structure (comb), which is seen to be developed best on special regions of the body (e.g. the distal segments of thoracic legs). The function of the cuticular structures–by analogy with other taxonomic groups–is discussed.     

Vemakylindrus cantabricus, a new species of Diastylidae (Crustacea, Cumacea) from the northern Iberian coasts

Eleven species of the genusVemakylindrus Bacescu, 1961 are known at present. A hitherto unknown species is described herein asV. cantabricus, sp. nov., and is compared with the more closely related congeneric species:V. hastatus (Hansen, 1920) andV. stebbingi Day, 1980.Vemakylindrus cantabricus may be distinguished from its congeners by a combination of the following characters: (1) carapace densely covered by hooked denticles and hairs; (2) pseudorostrum shorter than carapace; (3) telson of “Diastylis type” with 5–6 pairs of lateral spines; and (4) external process of basis of third maxilliped with 4 long plumose setae.     

Die Wachstumskosten vonPorcellio scaber (Crustacea,Isopoda)

The assimilation of food inPorcellio scaber, considered over the entire life cycle, follows a two-phase function with a turning point at a body weight of about 3 mg. It is assumed that an important factor in this relationship is the efficiency of digestion, which should depend on the surface/volume ratio of the mid-gut and on the speed with which food is passed through the intestine. Calculation of these values reveals a size-dependent drop in efficiency of digestion roughly following the “surface rule”. The drop in efficiency of digestion may pose to the system a problem of information retrieval since inefficient digestion increases the “noise” level against which specific “signals” have to be selected — that is, specific molecules have to be absorbed and used in syntheses of cell constitutents. In order to offset decreasing efficiency of digestion, the system would have to increase redundancy, e. g. by assimilating progressively more food and thus, inevitably, increasing “cost” of some kind. The young larvae ofP. scaber, up to a body weight of 3 mg, do, in fact increase the amount of food assimilated in proportion to the calculated increase in redundancy. At about this critical size a switch in metabolism seems to take place, and weight specific assimilation of food decreases despite the continuously dropping efficiency of digestion. The actual use that the organism makes of the food ingested is represented by the ratio assimilation/cost of redundancy. Calculation of this ratio over the whole life cycle shows it to parallel neatly the curve for the monthly growth rate of the species.