Ultrastructural observations on paracnids. I: Coelogynopora axi Sopott (Turbellaria,Proseriata)

The Schlauchdrüsen or paracnids of Coelogynopora axi Sopott, 1972 consist of two components: a muscle cell and a secretory cell.The secretory cell is provided with a tube, which bears a border of microvilli. In the normal position the tube is situated in the interior of the secretory cell, and the microvilli stand at the inner side of the tube. After expulsion of the tube the microvilli are situated at its free surface.The evagination takes place in response to chemical stimuli and is effected by the contraction of the myofibrils of the muscle cell.The paracnids are supposed to be mechanisms of defense.However, conformities with nematocysts and spirocysts of the cnidarians do not exist.The paracnids in other species of the Coelogynoporidae, for example in Invenusta paracnida (Karling, 1966) and Carenscoilia bidentata Sopott, 1972 differ from those of C. axi in many details.Abbreviations bl- basement lamina - ep- epidermis - hd- hemidesmosomes - mc- muscle cell - mt- microtubules - mv- microvilli - nsc- nucleus of the secretory cell - sb- bowl containing secretion granules - sc- secretory cell - sd- septate desmosome-like structures - sg- secretion granules - t- tube - tf- tonofilaments     

Turbellaria in the lagoon of Ghar-el-Melh. Research on the regenerative ability of Monocelis fusca Oersted (Turbellaria, Monocelididae)

The Turbellarian Monocelis fusca Oersted is abundant in the lagoon of Ghar-el-Melh. Traumatic regeneration in this animal is realised for the first time. Transversal sections through two levels of the body are made, and pointed out the presence or the absence of regeneration ability with the considered fragment.     

Ultrastructure of the spines in the copulatory organ of some Monocelididae (Turbellaria,Proseriata)

Summary A comparative ultrastructural study of the copulatory organ was carried out in four genera of Turbellaria-Monocelididae. In all four genera the male copulatory organ is of the conjuncta-duplex type and has a cirrus armed with spines. Fine-structural analysis of the cirrus spines reveals that these structures are specializations within the basement lamina of the cirrus. In this part of the male canal the basement lamina has a trilamellar structure. The spines are formed by a local thickening of the middle electron-dense layer and show a structural similarity in all the Monocelididae investigated.The systematic value of this character within the family Monocelididae is discussed.Abbreviations b bacteria - bl basement lamina - cr cell remnants - g granules of prostate glands - hd hemidesmosomes - l lumen of cirrus - m _c muscles of cirrus - m _b muscles of bulbus - mi mitochondria - p parenchymal elements - s spine - sp septum - st stylet - sz spermatozoa     

Population structure of the Monocelis lineata (Proseriata, Monocelididae) species complex assessed by phylogenetic analysis of the mitochondrial Cytochrome c Oxidase subunit I (COI) gene

Monocelis lineata consists of a complex of sibling species, widespread in the Mediterranean and Atlantic Ocean. Previous genetic analysis placed in evidence at least four sibling species. Nevertheless, this research was not conclusive enough to fully resolve the complex or to infer the phylogeny/phylogeography of the group. We designed specific primers aiming at obtaining partial sequences of the mtDNA gene Cytochrome c Oxidase subunit I (COI) of M. lineata, and have identified 25 different haplotypes in 32 analyzed individuals. The dendrogram generated by Neighbor-Joining analysis confirmed the differentiation between Atlantic and Mediterranean siblings, as well as the occurrence of at least two Mediterranean sibling species. Thus validated, the method here presented appears as a valuable tool in population genetics and biodiversity surveys on the Monocelis lineata complex.     

Three New Species of Minoninae (Turbellaria, Proseriata, Monocelididae) from the North Sea, with Remarks on the Taxonomy of the Subfamily

Three new species of Minoninae are described and a new genus is proposed for one of them: Minona degadti sp.n., Duplominona septentrionalis sp.n. and Duploperaclistus circocirrus gen. et sp.n. All three species occur in sublittoral sandy habitats in the Southern Bight of the North Sea, but D. circocirrus has also been found at a littoral station. The taxonomy within the subfamily Minoninae is discussed. Seven genera are considered as valid, and they are briefly diagnosed. " Peraclistus ituipus" sensu Westblad (1952) (= Duplominona westbladi Karling, 1966) is included in the new genus as Duploperuclistus westbladi (Karling, 1966) comb.n.     

Phylogenetic relationships within the Archiloa genus complex (Proseriata,Monocelididae)

Of the seven genera which we have recognised within the Archiloa genus complex sensu Karling (1966) the cosmopolitan genus Archilina is the most primitive and is characterised only by plesiomorphic characters, and has to be considered paraphyletic. All other species of the Archiloa genus complex are hypothesized to be derived from Archilina-like ancestors through different evolutionary lineages. One lineage led to the genera Archiloa, Inaloa, Archilopsis and Monocelopsis, taxa found in the Atlantic and the Mediterranean. These genera are monophyletic and their relationships are analyzed. The genera Mesoda (Brazil) and Tajikina (Northern Pacific) can be considered as two other separate lineages. Similarly, within what we now consider as the genus Archilina different lineages can be recognized in different regions.     

Ultrastruktur pericerebraler Cilienaggregate beiDicoelandropora atriopapillata Ax undNotocaryoplanella glandulosa Ax (Turbellaria,Proseriata)

Zusammenfassung Die Ultrastruktur pericerebral gelegener Cilienaggregate vonDicoelandropora atriopapillata Ax, 1956, undNotocaryoplanella glandulosa (Ax, 1951) wird beschrieben. Die intracellulÄren Aggregate setzen sich jeweils aus mehreren 100 Cilien zusammen, die lückenlos alternierend angeordnet und distal miteinander verflochten sind. Für die Cilienaggregate wird eine photoreceptorische Funktion wahrscheinlich gemacht.

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Ultrastructure of pericerebrally located ciliary aggregations inDicoelandropora atriopapillata Ax andNotocaryoplanella glandulosa Ax (Turbellaria, Proseriata)

Summary The ultrastructure of pericerebrally located ciliary aggregations inDicoelandropora atriopapillata Ax, 1956, andNotocaryoplanella glandulosa (Ax, 1951) is described. The intracellular aggregations consist of some 100 cilia, which are arranged in an alternating position without gaps. The distal parts of the cilia are interweaved. The aggregations are interpreted as photoreceptors.

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Abkürzungen af aktinÄhnliche Filamente - bk Basalkörper - c Gehirn - ca Glienaggregat - cm ciliÄre Mikrotubuli - ep Epidermis - mi Mitochondrium - mt Mikrotubuli - n Kern - pn Protonephridium - rr rostrales Ringband - sk Sehkolben - st Statocyste - tb Tastborste - vk ventrale KriechsohleDie Arbeit wurde durch Mittel der Akademie der Wissenschaften und der Literatur in Mainz gefördert. — Für technische Assistenz danken wir Frl. E. Hildenhagen     

Observations on the ultrastructure of the copulatory organ of Archilopsis unipunctata (Fabricius, 1826) (Proseriata,Monocelididae)

The copulatory organ in adult specimens of Archilopsis unipunctata has been studied by transmission electron microscopy.This copulatory organ is of the conjuncta-duplex type with eversible cirrus. The seminal vesicle, lined with a nucleate epithelium, is surrounded by spirally arranged muscles. The fibres are enclosed in a sheath that is continuous with the septum of the bulbus and the basement lamina of the male canal epithelium. Distally to the seminal vesicle the bulbus is filled with the secretory cell-necks of the prostate glands. The male canal shows three different parts: seminal duct, ejaculatory duct and eversible cirrus. At the transition of seminal duct and ejaculatory duct two prostate ducts open into the lumen. The structure of the epithelium lining the different parts of the canal is described. The transition into the cirrus may be recognized by an abrupt change in the thickness, the electron density and the stratification in the basement lamina and by the disappearance of the epithelium absent indeed in the cirrus. The material found inside the cirrus-lumen is different according to the zone considered. The origin of this material and of the cirrus teeth is discussed.Abbreviations ab- apoptotic body - ba- bacteria - bb- basal bodies of cilia - bl- basement lamina - bw- body wall - c- cilia - cb- cell body - cgp- common genital porus - ci- cirrus - cip- cirrus plug - cl- lumen of cirrus - cm- circular muscles - cr- cytoplasmatic remnants - cs- cytoplasmatic sheets - ejd- ejaculatory duct - ep_ej- epithelium of ejaculatory duct - d- desmosomes - f- flagella of spermatozoa - fd- female duct - fp- female porus - gc- golgi complex - gl- glycogen particles - hd- hemidesmosomes - lm- longitudinal muscles - ly- lysosome-like body - m- muscles - m_b- muscles of the bulbus - m_c- muscles of the cirrus - m_c- muscles of the seminal vesicle - mi- mitochondria - ml- microvilli - ms- mesenchyme - n_sd- nuclei of the seminal duct - pd- prostate duct - pg- prostate glands - ri- ribosomes - s- septum - sb- secretory vesicle - sd- seminal duct - sp- spines - sv- seminal vesicle - v- vagina - vd- vas deferens     

Zwei neue Coe/ogynopora-Arten (Turbellaria, Proseriata) aus dem marinen Sublitoral

Coelogynopora sieinooecki sp.n. and C. hamulis sp.n., are described from sublittoral sediments of the North Sea. C. hamulis also occurs in an eulittoral lower beach slope.     

On the Genus Peraclistus (Turbellaria, Proseriata), with Redescription of P. oofagus (Friedman)

A new interpretation of the anatomy and systematic position of Peraclistus oofagus , an ectocommensal on the queen crab, Chionoecetis opilio , is presented. P. oofagus is redescribed and it is claimed that the original interpretation was erroneous. The genus Peraclistus is redefined both on the basis of this study and on examination of the type material, of the other members of this genus.     

Karyometrical analysis of 10 species of the subfamily Monocelidinae (Proseriata,Platyhelminthes) with remarks on the karyological evolution of the Monocelididae

Ten species of the Monocelidinae have been examined. All were found to be regularly diploid. Four of them show the chromosome number n=3 and remarkably similar karyotypes (one pair of large metacentrics, one pair of medium sized metacentrics and one pair of small heterobrachial chromosomes). This set is considered as basic (plesiomorphic) for the family Monocelididae. Three species present n=4 and three species n=5, with an increase of heterobrachial chromosomes. Based on karyometrical data, it is suggested that these complements are derived from the basic complement through fission of one or both metacentric chromosomes, respectively. Further minor chromosome rearrangements, involving centromere position, were observed.     

Organization of statocysts in the Otoplanidae (Plathelminthes): an ultrastructural analysis with implications for the phylogeny of the Proseriata

Summary The statocyst of otoplanids is enveloped by a bipartite capsule which consists of two different extracellular matrices. This capsule encircles three different types of aciliary cells: several peripherally located flattened parietal cells, one central statolith forming cell (lithocyte) and two clusters of accessory cells. Intracapsular lumina exist which are different from extracapsular intercellular spaces. The accessory cells most probably represent those structures that are mainly involved in nervous conduction. These cells extend cytoplasmatic processes towards different peripheral regions of the statocyst where processes of outer nerve cells penetrate the capsule. The statocyst does not seem to represent a more evolved equilibrium receptor system but may function as a relatively simple aciliary sense organ suitable for positive geotactic behaviour. The otoplanid statocyst corresponds to statocysts in other lithophorous proseriates but not to statocysts in other taxa of the free-living Plathelminthes. The monophyly of a taxon Lithophora within the Proseriata is corroborated by this autapomorphic characteristic.Abbreviations ac accessory cell(s) - c capsule of the statocyst - ce cerebrum - ci cephalic intestine - co capsule opening - cp cell process(es) of accessory cell(s) and cell(s) containing filaments - ecm extracellular matrix - fc cell(s) containing filaments - ic intercellular spaces within the capsule - mc muscle cell(s) - n lobed nucleus of the lithocyte - nac nucleus (nuclei) of accessory cell(s) - nc nerve cell(s) - npc nucleus (nuclei) of parietal cell(s) - pc parietal cell(s) - s statolith - sc statolith cell (lithocyte)     

Electron microscopical observations on vitellocytes and germocytes inNematoplana coelogynoporoides (Plathelminthes,Proseriata)

Summary Fine-structural features of vitellaria and germaria inNematoplana coelogynoporoides are documented and compared with those of other free-living plathelminths with ectolecithal eggs. Emphasis is mainly put on the pattern of eggshell material, yolk bodies deposited in vitellocytes, and marginal granules of the female germ cells. In this species, encompassed in the taxon Proseriata Unguiphora, the eggshell granules show a meandering pattern also known from species of the taxon Proseriata Lithophora. In contrast, the yolk globules exhibit crystalline components unknown from the Lithophora. The marginal granules in the ooplasm have an extremely large diameter. They consist of a flocculent core and a crescent-shaped cortex. Marginal granules of this appearance have not been found in any other taxon of free-living Neoophora.Abbreviations cc crystalline component - co cortex - gER granular endoplasmic reticulum - go Golgi complex - gl glycogen - lp lipid droplet - mg marginal granule - n nucleus - nl nucleolus - sg eggshell granule - sp spermatozoa - yg yolk globule     

Ultrastructural observations on gastrodermal regeneration in the planarian Dugesia japonica (Turbellaria)

The earliest detectable change during regeneration of the gastrodermis in Dugesia japonica was an aggregation of regenerative cells underneath the gastrodermis remaining at the wound margin. The gastrodermal cells in experimental regenerates retained some of their original characters and presented no indication of cell dedifferentiation. The regenerative cells came into contact with the basal surface of gastrodermal cells, forming stratified cell layers. Differentiation of these cells into gastrodermal cells was initiated by the development of synthetic organelles within their cytoplasm. These differentiating cells gave rise to two different types of gastrodermal cells, namely phagocytic cells and sphere cells. In later stages, there was an apparent movement of differentiated gastrodermal cells towards the parenchyma.     

Some observations on two populations of Dalyellia Viridis (G. Shaw) (Turbellaria: Neorhabdocoela) living in temporary habitats in England

Certain aspects of the biology of two populations of D. viridis living in Massam's Slack North and a drainage ditch skirting the Hightown Road, Lancs. were studied. The habitats are described; both are devoid of water for several months during the summer/autumn. Sampling techniques are described. Changes in the numbers and size-structure of both populations were studied. After the re-flooding of the habitats, one to a few months elapsed before hatching of cocoons of D. viridis occurred; in both habitats hatching occurred earlier after the drought in 1970 than after the dry period in 1969; hatching ceased by April in the drainage ditch (Hightown) and bij May in Massam's Slack. In both populations animals were still growing into the larger size-categories when the habitats became dry, in June in the case of Massam's Slack and in May in the case of the drainage ditch (Hightown). Cocoon formation started when animals reached a length of 2.0 mm. The maximum number of cocoons observed was 24. Cocoon size varied from 245 × 127 mm to 294 × 137 mm. When first formed the penis stylet does not possess handles; as the stylet grows so the handles, the lateral distal branches, and spines increase in size. The total length of stylet varied from 74 to 370 µm according to the size of specimen examined; the average, minimum and maximum lengths recorded in specimens in the 3.0 mm size-group was 338 µm, 313 µm and 370 µm respectively. The data gleaned on the above aspects of the biology of D. viridis in the present study are compared with some available information presented in previous publications by continental workers.     

Karyological investigations on seven weevil species (Coleoptera, Curculionidae)

Karyological studies were carried out on seven Palaearctic weevils. The following chromosome numbers were found in individual species, i.e. Otiorhynchus niger (F.), Phyllobius viridearis (Laich.), Phyllobius scutellaris Redt., Phyllobius calcaratus (F.), Polydrusus cervinus (L.), and Brachyderes incanus (L.) 2n = 22, n Male = 10 + Xyp, in Lixus elegantulus (Boh.) 2n = 22, n Male = 21 + Xyp. The heterochromosomes of all the examined species form, in the first meiotic metaphase, a typical parachute bivalent.