Fine structure of acrosome biogenesis and of mature sperm in the bivalve molluscs<Emphasis Type="Italic"> Glycymeris</Emphasis> sp. (Pteriomorphia) and<Emphasis Type="Italic"> Eurhomalea rufa</Emphasis> (Heterodonta)

Proacrosomal vesicles form during the pachytene stage, being synthetized by the Golgi complex in Glycymeris sp., and by both the Golgi and the rough endoplasmic reticulum in Eurhomalea rufa. During early spermiogenesis, a single acrosomal vesicle forms and its apex becomes linked to the plasma membrane while it migrates. In Glycymeris sp., the acrosomal vesicle then turns cap-shaped (1.8 μm) and acquires a complex substructure. In E. rufa, proacrosomal vesicles differentiate their contents while still at the premeiotic stage; as the acrosomal vesicle matures and its contents further differentiate, it elongates and becomes longer than the nucleus (3.2 μm), while the subacrosomal space develops a perforatorium. Before condensation, chromatin turns fibrillar in Glycymeris sp., whereas it acquires a cordonal pattern in E. rufa. Accordingly, the sperm nucleus of Glycymeris sp. is conical and elongated (8.3 μm), and that of E. rufa is short and ovoid (1.1 μm). In the midpiece (Glycymeris sp.: 1.1 μm; E. rufa: 0.8 μm), both species have four mitochondria encircling two linked orthogonal (Glycymeris sp.) or orthogonal and tilted (30–40°; E. rufa) centrioles. In comparison with other Arcoida species, sperm of Glycymeris sp. appear distinct due to the presence of an elongated nucleus, a highly differentiated acrosome, and four instead of five mitochondria. The same occurs with E. rufa regarding other Veneracea species, with the acrosome of the mature sperm strongly resembling that of the recent Mytilinae. Electronic Publication     

Fine structure of the ciliated epidermis on the tentacles ofOwenia fusiformis (Polychaeta,Oweniidae)

Summary The ultrastructure of the epithelium on the oral surface of the tentacles ofOwenia fusiformis has been studied by light and electron microscopy. Unspecialized monociliated cells are the dominant cell type of the epithelium; however, biciliated epidermal cells, monociliated mucous cells and non-ciliated cells are also present. In all of the ciliated cells each cilium is provided with a diplosomal basal body and two striated rootlets. The cytological features of this unspecialized epithelium strongly resemble those of similar epithelia in the Phoronida, Brachiopoda and Hemichordata. So far,O. fusiformis is the only polychaete known to possess an unspecialized monociliated epidermis. Other characters ofOwenia are also mentioned. The relationship between the nervous system and the epidermal cells on the tentacles is examined. It is proposed thatOwenia should assume an important role in discussions of the phylogeny of the Polychaeta.I wish to thank Dr. R.M. Rieger for his inspiration and guidance during the course of this study. Ms. Wilma Hanton provided technical assistance for the electron microscopy. This work was supported by NSF Grant # GB-42211 to R.M. Rieger     

New records of minute litter-decomposing basidiomycetes from Japan.Actiniceps thwaitesii (Pterulaceae) new to Japan andAnastrophella podocarpicola sp. nov. (Tricholomataceae)

Actiniceps thwaitesii (Pterulaceae) new to Japan andAnastrophella podocarpicola sp. nov. (Tricholomataceae) are described and illustrated. The former is characterized by forming stipitate-capitate basidiomata under 1 mm tall with encrusted cystidia and acanthophyses. The latter, occurring on a decaying leaf ofPodocarpus macrophyllus, differs from other taxa ofAnastrophella in having undifferentiated hymenial cystidia and smaller basidiospores and basidia. Their cultural features are also presented.     

Ultrastructure of Euspermiogenesis in the Mesogastropod Stenothyra sp. (Prosobranchia, Rissoacea, Stenothyridae)

The structure of mature and developing euspermatozoa of the rissoacean gastropod Stenothyra sp. has been studied using transmission electron microscopy. During cuspermiogenesis nuclei pass through fibrillar and lamellar phases of condensation. A Golgi-derived acrosome attaches to the nucleus during the fibrillar phase. Spherical mitochondria of early euspermatids fuse to form the mitochondrial sheath which undergoes metamorphosis to form helical midpiece elements, paracrystalline material and helical midpiece compartments. Mature euspermatozoa consist of a flat acrosome (acrosomal cone, axial rod, basal plate), short curved nucleus (2.5–2.8 μm) and elongate midpiece and glycogen piece. Coarse fibres associated with the axoneme emerge from a posterior invagination of the nucleus and continue into the initial portion of the midpiece. In the proximal portion of the midpiece, two helical compartments (filled with membranous material) are present—only one of which persists further posteriorly. No compartments occur in the distal region of the midpiece. Posterior to the midpiece, the axoneme is surrounded by tightly-packed (glycogen) granules and terminates within this region. The distal end of the euspermatozoon consists solely of glycogen granules surrounded by the plasma membrane. Although coarse fibres (associated with the axoneme), midpiece paracrystalline material and helical compartments are commonly reported in sperm of euthyneuran gastropods, this represents the first report of all three features in any prosobranch euspermatozoon.     

Orthogonikleithrus leichi n. gen., n. sp. (pisces: teleostei) from the late jurassic of Germany

Orthogonikleithrus leichi n. gen and n. sp. from the Late Jurassic of Zandt, W-Germany resemblesLeptolepides in the supra- and infraorbital sensory canals and in the length of the anterior process of the maxilla, andAscalabos in the massive aspect of the premaxilla. The caudal skeleton has some similarities with that ofLeptolepides (e. g. the broadening of the neural and haemal spines of the last caudal vertebrae, length of uroneurals 1 and 2), but also with that ofAnaethalion (in the neural arches above preural centrum 1 and ural centra). According to this combination of features, the fish remains as Elopocephala incertae sedis.     

FEEDING OBSERVATIONS ON ACTEON TORNATILIS (LINNAEUS) (OPISTHOBRANCHIA: ACTEONIDAE)

The prey of the opisthobranch Acteon tornatilis (Linnaeus) andthe method of attack by the predator are described. The resultsof a series of choice experiments suggest that the preferredprey is the polychaete Owenia fusiformis Delle Chiaje, althoughLanice conchilega (Pallas) is also favoured. (Received 5 February 1988; accepted 29 April 1988)     

Specificity of a strain ofNeozygites sp. (Zygomycetes: Entomophthorales) toMononychellus tanajoa (Acari: Tetranychidae)

Neozygites sp. is commonly found infecting the cassava green mite,Mononychellus tanajoa (Bondar), in parts of northeast Brazil. The introduction of this fungus into other regions requires the knowledge of its specificity, especially in relation to natural enemies of different cassava pests. Laboratory tests indicated the development of germination tubes ofNeozygites in some females ofTetranychus bastosi Tuttle et al. andT. urticae Koch, with subsequent formation of a reduced number of hyphal bodies in someT. bastosi. No females of the phytoseiid predatorsAmblyseius idaeus (Denmark & Muma) andAmblyseius limonicus Garman & McGregor s.l. were infected byNeozygites sp.     

The sperm of Hylodinae species (Anura, Leptodactylidae): Ultrastructural characteristics and their relevance to interspecific taxonomic relationships

Aaabstract Hylodinae leptodactylids(sensu Lynch 1971) form a group of diurnal frogs, which is hypothesized on the basis of morphological traits to be the closest relatives of the dendrobatid frogs. Our study describes ultrastructural characteristics of sperm from three hylodine species(Hylodes phyllodes, Crossodactylus sp. n. andMegaelosia massarti) to reassess the intergeneric relationships within the Hylodinae, as well as the supposed relationship between the Hylodinae and Dendrobatidae. The ultrastructure of the sperm is very similar among the three species and is indicative of its conserved nature within the Hylodinae. The structure of the acrosomal complex was very similar to that of other leptodactylid species, to most of the remaining species included in the Bufonoidea lineage, and also to that observed in the dendrobatid species examined so far. Since such a structure has been considered a plesiomorphic trait, it contributes little to our understanding of the relationships between the Hylodinae and Dendrobatidae. The flagellar apparatus ofCrossodactylus sp. n. is very similar to that of most leptodactylids. The sperm ofMegaelosia massarti andHylodes phyllodes display a distinctive condition in their axial and juxtaxonemal fibers. This distinctive flagellar condition expands the already known variability in sperm structure within the Leptodactylidae.     

The status ofBemisia tabaci (Hom.: Aleyrodidae),Trialeurodes vaporariorum (Hom.: Aleyrodidae) and their natural enemies in Crete

The non «B» biotype ofBemisia tabaci (Gennadius) is recorded for the first time in Crete in 1992, in the north east and south east of the island.Trialeurodes vaporariorum (Westwood) is the predominant whitefly on plants in the north and west of the island. Three surveys of Crete were made in 1992 and 1993 for natural enemies ofB. tabaci andT. vaporariorum and resulted in the collection of 4 species ofEncarsia, (plus a number of species that are unidentifiable at this time), anEretmocerus sp. (unidentifiable at this time) and a fungal pathogen,Paecilomyces farinosus (Dickson Ex Fries) Brown &; Smith.Encarsia adrianae was identified fromT. vaporariorum; which constitutes its most westerly distribution point and a new host record respectively.B. tabaci andT. vaporariorum were found on horticultural crops, ornamentals and weeds. Populations of both whitefly species were severely depleted on field hosts throughout the island during the winter of 1992/93. Climatic constraints, competition withT. vaporariorum in otherwise suitable niches, effective natural enemies and an observed low level of polyphagy may explain the present limited distribution of the non «B» biotype ofB. tabaci in Crete.     

Hemicycliophora hellenica n. sp. (Nemata: Criconematidae) from Greece

Hemicycliophora hellenica n. sp. is described and illustrated from a bisexual population found in Filippias, Epirus, Greece, in the rhizosphere of giant reed (Arundo donax) and unidentified aquatic plants along the edge of irrigation canals. Hemicycliophora hellenica n. sp. is characterized by a long stylet (more than 120 µm), body length (L = 1,078-1,634 µm; R = 303-362), and lateral field marked by three lateral lines in females and four in males. The lip region is distinctive in that the female labial disc is oval and offset from the first lip region annule, and protrudes markedly; the male labial disc is very large, offset and rectangular, and protrudes distinctly. Hemicycliophora hellenica n. sp. resembles H. megalodiscus Loof by possession of a strongly protruding labial disc, but differs in having a longer female body, more body annules, longer stylet, and dorsally and ventrally indented head annules. The male labial plate is larger than in H. megalodiscus, and the male has four incisures in the lateral field vs. three in H. megalodiscus.     

COMPARATIVE SPERM MORPHOLOGY OF THE PULMONATE LIMPETS TRIMUSCULUS COSTATUS, T. RETICULATUS (TRIMUSCULIDAE) AND BURNUPIA STENOCHORIAS AND ANCYLUS FLUVIATILIS (ANCYLIDAE)

Sperm ultrastructure is described for the first time in representativesof the pulmonate ‘limpet’ families Trimusculidae(Trimusculus costatus, T. reticulatus: marine) and Ancylidae(Burnupia stenochorias, Ancylus fluviatilis: freshwater). Allshow characteristic heterobranch sperm features (a spheroidalacrosomal vesicle supported by an acrosomal pedestal; a helicallykeeled nucleus and a complex, very elongate midpiece featuringparacrystalline and matrix layers sheathing the axoneme, coarsefibers and one or more glycogen helices). Posterior to the midpiece,a glycogen piece (axoneme sheathed by glycogen granules) andannulus are also present in all species. Taxonomically usefuldifferences in the shape and dimensions of the acrosome, nucleusand midpiece occur between the species. Results support thedecision of recent workers to transfer the Trimusculidae fromthe Siphonarioidea to a separate superfamily Trimusculoidea(characteristic sperm features including: narrow acrosomal pedestaloverlapping with nuclear apex; heavily keeled nucleus; midpiecewith strongly projecting secondary and glycogen helices). Therelationship of the Trimusculoidea to other pulmonates, as indicatedby sperm ultrastructure, remains uncertain largely because comparativedata for several important groups are unavailable. Spermatozoaof the two ancylids most closely resemble those of other investigatedplanor-boideans and to a lesser extent, those of the Lym-naeoidea.However, differences between Burnupia stenochorias (unique(?)accessory structure on the acrosomal pedestal; glycogen wedgeswithin the nuclear fossa; other features similar to planorbids)and Ancylus fluviatilis (all sperm features very similar toplanorbids) suggests that these patelliform ancylids are notclosely related. (Received 20 November 1997; accepted 23 January 1998)     

The genusNephtys (Polychaeta: Phyllodocida) of northern Europe: A review of species,including the description ofN. pulchra sp. n. and a key to the Nephtyidae

Twelve species ofNephtys now known from northern Europe are described, including one new species,N. pulchra sp. n. A key is provided to the 14 species of Nephtyidae, from the region. Geographic changes in the setiger in which interramal cirri first occur are recognized inN. caeca (Fabricius),N. ciliata (Müller),N. hombergii Savigny andN. pente Rainer.     

Die Tentakuliten aus dem Frasnium (Ober-Devon) von Ghuk (westliches Zentral-Afghanistan)

Frasnian tentaculites from western part of Central-Afghanistan are described. Six of the 11 studied species are new:Dicricoconus dupliannulatus n. sp.,Dicricoconus ghukensis n. sp.,Dicricoconus gracilis n. sp.,Dicricoconus harundata n. sp.,Volynites kaminjensis n. sp. andAlternatus spatiosus n. sp. The fauna is appearing in two stratigraphic levels. The occurrence ofTentaculites donensis respectively ofDicricoconus tichomirovi, Dicricoconus tragula andUniconus livnensis confirmes the middle-upperfrasnian respectively the upperfrasnian age of both levels. The Devonian basin of Ghuk area was connected with the epicontinental sea of the Russian Plateform throughout the Frasnian and with the Libyan basin at least during upperfrasnian time.     

中缅树鼩精子形态特征及冷冻损伤

树鼩作为一种新型的、接近灵长类的实验动物,在医学生物学上的应用受到越来越多的重视。精子的结构特性研究及冷冻后结构的完整性分析是精子生物学的主要内容,也有助于树鼩的实验室快速繁殖。该研究采用人工饲养的中缅树鼩(Tupaia belangeri chinensis),结果显示其睾丸占总体重的(1.05±0.07)%,总体积为(1.12±0.10)mL。附睾尾及输精管精子总量估计在2.2×107～8.8×107,其运动度和顶体完整率分别为(68.8±3.9)%和(90.0±2.1)%。利用扫描电子显微镜和透射电子显微镜对树鼩附睾精子的超微结构进行的观察和分析显示精子头部呈圆形或卵圆形;头部长度、宽度平均分别为6.65和5.82μm;精子尾部中段、主段、尾段和精子总长度平均分别为13.39、52.35、65.74和73.05μm;尾部中段的线粒体螺旋数量为48个,其轴丝结构为典型的"9+9+2"结构。冷冻解冻后的精子主要表现在顶体与质膜不完整、精子断裂、尾部扭曲和膨大。上述结果提示树鼩精子与其他哺乳动物精子的结构特征相似,但是精子大小和线粒体螺旋数目有明显的差别,且超微结构改变仍是冷冻精子运动和受精能力下降的主要原因。     

Identification ofStreptomyces sp. Tc022, an endophyte inAlpinia galanga, and the isolation of actinomycin D

Some endophytic actinomycetes (120) were isolated from the roots ofAlpinia galanga. Identification of these endophytes was based on their morphology and amino acid composition of the whole-cell extract. Most isolates were classified aStreptomyces sp. (82), with the remainder belonging toNocardia sp. (11),Microbispora sp. (3) andMicromonospora sp. (2). Eight isolates were unclassified and 14 were lost during subculture. The strain identified as endophyticStreptomyces sp. Tc022 strongly inhibitedColletotrichum musae andCandida albicans. This endophyte was cultured, the agar was extracted with organic solvent and the extract was purified on a column of silica gel to give a major component, which was identified to be actinomycin D on the basis of spectroscopic dat Actinomycin D showed antifungal activity againstColletotrichum musae andCandida albicans with the MIC of 10 and 20 mg ml^?1, respectively.     

The genusOligolecithus Vercammen-Grandjean (Digenea: Telorchiidae) fromXenopus spp. (Anura: Pipidae), with a description ofO. siluranae n. sp. fromX. tropicalis (Gray) in Ghana

The taxonomy, host range and geographical distribution ofOligolecithus Vercammen-Grandjean, 1960, a genus of telorchiid digeneans fromXenopus spp. in Africa, is reviewed.O. jonkershoekensis Pritchard, 1964 is established as a junior synonym ofO. elianae Vercammen-Grandjean, 1960, andO. siluranae n. sp. is described fromX. tropicalis in Ghana. These two species are differentiated by variations in body length, testicular arrangement and ventral sucker width in proportion to body size.O. elianae occurs inX. laevis laevis from South Africa and Zimbabwe (new locality record),X. l. poweri from Zaire,X. l. victorianus from Zaire, Uganda and Rwanda (new locality record),X. l. bunyoniensis (new host record) from Uganda andX. l. sudanensis from Sudan (new host and locality record). It is also found inX. wittei from Uganda and Zaire andX. vestitus (new host record) from Uganda. The host ofO. siluranae belongs to a separate species group within the genusXenopus from the hosts ofO. elianae; this tropicalis group is phylogenetically isolated, but it also occurs in a different biotype, lowland tropical rain forest, ecologically distinct from the other known host species.     

Inter- and intraspecific variation of nuclear DNA reassociation kinetics in the Gracilariales (Rhodophyta)

DNA reassociation kinetics were used to determine inter- and intraspecific variation in genome organization and complexities in species ofGracilaria andGracilariopsis. Results indicate the presence of three second order components corresponding to fast, intermediate and slow fractions. Repeated sequences varied from 13–95%. Three geographic populations ofGracilaria tikvahiae were similar with 13–27% repeated sequences.Gracilaria sp. cultivars G-1 and G-6 with 35% and 95% repeated sequences, respectively, were distinct from each other andG. tikvahiae. No pattern of genome organization and complexity was found which permitted a distinction betweenGracilaria andGracilariopsis. Comparison of the percent of unique and repetitive sequences (U/R) indicated a wide range of ratios, withGracilaria tikvahiae populations having the highest values (2.7–7.3) andGracilaria sp. cultivar G-6,G. blodgettii andGracilariopsis lemanieformis the lowest (0.05–1.80). Unique component complexities varied one order of magnitude, from 10⁸ forGracilaria takvahiae to 10⁷ forGracilaria sp. cultivar G-6,G. blodgettii andGracilariopsis lemanieformis. Information for genome size, organization and complexity is used to develop a nuclear genome profile forGracilaria blodgettii andGracilariopsis lemanieformis which are characterized by commercial grade agars having high gel strengths (> 700 g cm^?2) and elevated melting temperatures (99 °C).     

Strongyloides spearei n. sp. (Nematoda: Strongyloididae) from the common wombatVombatus ursinus (Marsupialia: Vombatidae)

Strongyloides spearei n. sp. is described from the small intestine of the common wombatVombatus ursinus from Healesville, Victoria. The new species is distinguished from all known congeners by: the triangular shape of the stoma and the length of the parasitic female; the blunt spicules in the free-living male; and the presence of eggs in the faeces of the host.S. spearei andS. thylacis Mackerras, 1959 form a separate group withinStrongyloides based on both species infecting marsupials, having directly recurrent ovaries in the parasitic female and having blunt spicules in the free-living male. The histological localisation ofS. spearei is predominantly within the crypts of the small intestine.     

Life cycle and host specificity ofEutinobothrus sp. (Col.: curculionidae) an agent for biological control ofSida acuta (malvaceae) in the northern territory,Australia

The biology of an undescribed weevil,Eutinobothrus sp., and its specificity toSida acuta, a serious weed in northern Australia, were studied in a quarantine facility in Australia. Sixty-eight plant species were screened and onlyS. acuta andS. rhombifolia could sustain populations ofEutinobothrus sp. Adults feed externally on the stems and oviposit in feeding scars. Larvae feed internally and pupate in the stem. Prepupae and pupae may aestivate in the stem and adults emerge with the onset of the wet season when new growth is evident.Eutinobothrus sp. was released in January, 1994 in the Northern Territory and has established.