Ephemerella readeri Müll. Hal. (Physcomitrella readeri (Müll. Hal.) I.G. Stone & G.A.M. Scott,Funariidae, Bryophyta): a genus and species new to Europe

Abstract

A morphological and molecular analysis of a Physcomitrella, collected from a reservoir margin in the north of England, revealed this to be P. readeri, a species new to Europe. The present study clarifies previous confusion over the taxonomy of P. readeri showing it to be clearly distinct in both sporophytic and gametophytic characters from P. patens and uniform across its world range from England to USA, Japan and Australasia. While phylograms of the ITS1 region from both the Physcomitrella species, Physcomitrium pyriforme (Hedw.) Bruch & Schimp., Enthosthodon attenuatus (Dicks.) Bryhn and Funaria hygrometrica Hedw., place the first two in separate clades, in ITS2 phylograms they occur as sister taxa. This, together with previous genealogical studies on the speciation history of the Physcomitrella–Physcomitrium species complex, and morphology, suggests that generic rank is appropriate for P. readeri. We therefore reinstate the original name Ephemerella readeri Müll. Hal. Recent records at several reservoirs in England indicate that E. readeri may be native to UK, though remarkable congruence in ITS1 with Australian plants also suggests recent arrival as an alternative possibility.     

Resistenzprüfung von Kartoffelsorten gegenüberHeterodera schachtii Schmidt.

Zusammenfassung Die vom Reichsnährstand zum Handel zugelassenen Kartoffelsorten wurden auf ihr Verhalten gegenüber dem Kartoffelnematoden (Heterodera schachtii) in Infektions- und Freilandversuchen geprüft. Das Infektionsverfahren ermöglicht eine genaue Bestimmung des Cystenbesatzes in kurzer Zeit und hat den Vorteil, daß auf geringem Raum gleichzeitig eine große Anzahl Sorten geprüft werden kann. Die Mängel des Verfahrens werden kurz erläutert. Nach dieser Methode ergaben sich erhebliche Schwankungen im Befall. Vor allem gibt es aber keine unmittelbaren Beziehungen zwischen Nematodenbesatz und Pflanzenwuchs. Bei der Feldprüfung wurden die Sorten mehrere Jahre hindurch auf verseuchtem Boden auf ihren Gesundheitszustand, ihren Cystenbesatz und ihre Ertragshöhe untersucht. Während die Mehrzahl der Sorten den Anforderungen nicht entsprach und meist unbefriedigende Erträge brachte, erwiesen sich einige als bedingt resistent (tolerant). Diese Erscheinung deutet noch nicht auf das Vorhandensein eines Resistenzfaktors hin, sondern ist vermutlich auf die späte Reife der Sorten zurückzuführen.     

Resupinate basidiomycetes from Costa Rica. Myxariaceae s. Jülich, Sebacinaceae Wells & Oberw., and Tremellodendropsidaceae Jülich

Thirteen representatives of Myxariaceae sensu Jülich: Heterochaetella brachyspora (Bourdot & Galzin) Luck-Allen, Myxarium atratum (Peck) Ginns & Lefebvre, M. granulum Hauersl., M. laccatum (Bourdot & Galzin) Reid, M. mesomorphum (Bourdot & Galzin) Haursl., M. mesonucleatum Kisim., Oberw. & L.D. Gómez nov. sp., M. subsphaerosporum Kisim., Oberw. & L.D. Gómez nov. sp., Protodontia subgelatinosa (Karst.) Pilát; Pseudohydum gelatinosum (Fr.) P. Karst., P. gelatinosum var. paucidentata Lowy; one species of Sebacinaceae, Efibulobasidium albescens (Sacc. & Malbr.) K. Wells; and the Tremellodrendropisidaceae Tremellodendropsis flagelliformis (Berk.) Crawford var.ovalispora Crawford, are reported or described from Costa Rica. The corticioid Cystidiodontia artocreas (Berk & Curt. ex Cooke) Hjortstam is also reported from Costa Rica.     

Chlorosphaeropsis epidemica,spec. nova,eine neue Grünalge mit endophytischer Lebensweise

The new parasitic algaChlorosphaeropsis epidemica is a member of theChlorosarcinales and lives endophytically in the leaf-tissue ofPotamogeton species. It forms stacks of cells and appears in great numbers, especially in dying leaf-blades. Sexual reproduction is described for the first time in this genus. Apart from its endophytic way of life,Chl. epidemica is characterized by mononuclear cells with a parietal chloroplast of irregular thickness and with a few perforations, sometimes of complicated reticulate shape, and with 1–5 pyrenoids. The usually sphaerical gametes (respectively zoospores) are provided with two equal flagella, a parietal plastid, one pyrenoid and one stigma. In connection with the asexual reproduction the terms vegetative division and desmoschisis are critically discussed.

     

Die Spermiohistogenese des Süßwasser-Ostracoden Notodromas monacha O. F. Müller

Zusammenfassung Die Frühstadien der Spermiohistogenese des Süßwasser-Ostracoden Notodromas monacha, ovale und spindelförmige Spermatiden, werden phasen- und elektronenoptisch untersucht. Die ovalen Spermatiden sind gekennzeichnet durch das Auftreten von Caryomeren, die zu einem einheitlichen Nucleus verschmelzen, und durch die Zusammenlagerung aller Mitochondrien zu einem Nebenkern, aus dem sich zwei Derivate differenzieren. Die spindelförmigen Spermatiden gehen aus den ovalen hervor, indem Kern und Nebenkern-Derivate sowie die Zelle selbst Spindelform annehmen. Der Kern ist durch drei hinsichtlich ihrer Größe und Lage unterschiedliche granuläre Körperchen und einen von einer Doppelmembran umgebenen Bezirk ausgezeichnet. Ein Centriol konnte bisher nicht nachgewiesen werden.

---

The spermiogenesis of the fresh-water ostracod Notodromas monacha O.F. Müller

Summary In Notodromas monacha the early stages of the spermiohistogenesis (oval and spindle-like spermatids) have been studied by means of phase contrast and electron microscopy. Oval spermatids are marked by the presence of caryomeres, which during development fuse to form a single nucleus. All mitochondria are accumulated in a Nebenkern which is differentiated into two derivatives. The nucleus, the Nebenkern-derivatives and the cell body become spindle-shaped and thereby the oval spermatids are transformed to spindleshaped spermatids. The nucleus of the spindle-shaped forms is characterized by three granulated particles (different in size and position) and by a double-membrane bounded region. No centriole has been found in this study.

---

---

Für die Anregung zu diesen Untersuchungen sowie für Förderung und Diskussion danke ich meinem Lehrer, Herrn Professor Dr. Dr. h. c. W. E. Ankel.     

Die Speicheldrüsenchromosomen der StechmückeCulex Pipiens L. IV. Der Chromosomale Geschlechtsdimorphismus

In the salivary gland chromosomes of the mosquitoCulex pipiens L. band 10 C 3 of the small chromosome I in female larvae always shows a homozygous heterochromatic balloon, while male larvae are heterozygous for this structure, the homologous band being euchromatic. In males, heterozygous for a male-linked reciprocal translocation, the chromosome with the distinct euchromatic band is always involved in the segmental interchange with an autosome. It is concluded that the euchromatic state of band 10 C 3 represents the male-determining allelomorph, and the heterochromatic state the female-determining allelomorph (M and m, respectively). C. pipiens thus appears to be an excellent example of diplogenotypic determination of sex where the sexes are different in one pair of allelomorphs only. At the chromosomal level, this sexual dimorphism is expressed as a heterochromatic versus an euchromatic state of a single band. The significance of this observation is discussed in connection with the problem of the evolution of sex-determining mechanisms within the Nematocera.     

Die Speicheldrüsenchromosomen der StechmückeCulex pipiens L. III. Induzierte Chromosomale Aberrationen

Fifteen X-ray induced chromosomal aberrations in twelve autogenous lines of the mosquitoCulex pipiens were analysed: eight simple reciprocal translocations, one double reciprocal translocation, one translocation combined with an intrachromosomal transposition and a small deficiency, one simple transposition, and one pericentric inversion. The breakpoints were located on the morphological map of the salivary gland chromosomes. Their distribution seems to be random. A consideration of distances between breakpoints argues against the assumption of a linear order of chromosomes in the elongated sperm head. The extent of sterility in the heterozygote was recorded for 12 of the aberrations. Translocation heterozygotes, carrying the genetic pool of the lines here analysed, produced about 50% aneuploid gametes, independently of the length of the interstitiell segments.