Environmental correlates of population variables of perch (<Emphasis Type="Italic">Perca fluviatilis</Emphasis>) in boreal lakes

We examined relationships among perch population variable parameters in two types of lakes, lakes with perch (P-lakes, n?=?15) and lakes with perch and roach (PR-lakes, n?=?10) using redundancy analysis (RDA) to relate population variables to environmental factors. Effects from environmental factors were tested for significance by means of permutation tests (Monte Carlo). Three factors, pH, altitude and fraction of roach (by number) in the gill net catches, explaining 47.9% of the variation, had significant effects on perch population variables. The significance of pH was improved by partialing out the effect of conductivity and roach. Similarly, the significance of altitude was improved by partialing out the effect of pH and roach, and the significance of roach was improved by partialing out the effect of pH and altitude. When the fraction of pike in the catch was included in the analysis, the effect of roach was not significant and vice-versa, as roach and pike fractions were correlated with each other. The effect of pike was significant when roach was not included, but the effect was not as strong as the effect of roach. A biplot was constructed by plotting population variables on the first and second RDA axis, with arrows showing five selected environmental factors. Growth of 3+ to 5+ perch was positively related to pH and altitude, perch catch per unit effort was negatively related to pH and altitude, and age specific perch weight was negatively related to fraction of roach. The relationship between growth of 2+ perch and pH was not as strong as the relationship between pH and the growth of older perch. Moreover, the growth of 2+ perch was negatively related to the fraction of roach, probably due to competition between young zooplankton feeding perch and roach.     

Isolation of the <Emphasis Type="Italic">B</Emphasis> incompatibility factor mutants in <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis>

 B incompatibility factor mutants (Bmut) in Pleurotus ostreatus were recovered from common-B mating heterokaryons resulted from matings between wild-type monokaryons with different A but the same B factors (A1B2 and A2B2) after NTG mutagenesis. The mutant monokaryons such as A1B2mut and A2B2mut were observed to have regularly uninucleated hyphal cells and to be compatible with each other. Matings between A1B2mut and A2B2mut monokaryons produced stable heterokaryons (A1B2mut + A2B2mut) that had binucleated hyphal cells with true clamp connections and formed normal fruit-bodies. Mating tests using basidiospore progeny from each of these heterokaryons revealed the bipolar mating pattern. Genetic analysis suggested that the mutation of B factor in P. ostreatus might occur in the B incompatibility factor genes. Received: August 3, 2001 / Accepted: January 18, 2002     

A new species of <Emphasis Type="Italic">Ophiodothella</Emphasis> on <Emphasis Type="Italic">Casearia</Emphasis> from Venezuela

 Ophiodothella caseariae sp. nov. from leaves of Casearia tremula in Venezuela is described and illustrated. Received: February 19, 2002 / Accepted: April 30, 2002     

<Emphasis Type="Italic">Erysiphe patagoniaca</Emphasis>: a new species of <Emphasis Type="Italic">Erysiphe </Emphasis>sect. <Emphasis Type="Italic">Uncinula </Emphasis>from Patagonia,Argentina

 A new species of Erysiphe sect. Uncinula is described and illustrated from Patagonia, Argentina. Erysiphe patagoniaca sp. nov., found on leaves of Nothofagus × antarctica, is similar to E. nothofagi and E. kenjiana, but differs in its appendages being twisted throughout their length and the number of appendages, asci, and ascospores. The two endemic species of Erysiphe sect. Uncinula, E. magellanica and E. nothofagi, coexisted on the same leaves together with Erysiphe patagoniaca. Received: September 19, 2002 / Accepted: November 28, 2002 Acknowledgments The authors are grateful to Ms. Seiko Niinomi for providing the micrographs of ascomata of Erysiphe spp. on Nothofagus. Correspondence to:S. Takamatsu     

New species of <Emphasis Type="Italic">Clitocybe </Emphasis>and <Emphasis Type="Italic">Crepidotus </Emphasis>(Agaricales) from eastern Honshu,Japan

 Three new species of Agaricales from eastern Honshu, Japan, are described and illustrated. (1) Clitocybe minutella sp. nov. (section Vernae), having white, very small, clitocyboid basidiomata with white, strigose mycelial tomentum at the base of the stipe and trichodermial elements in the pileipellis, occurs on leaf litter in deciduous oak forests. (2) Crepidotus longicomatus sp.nov. (section Echinospori), forms very small (up to 3.5 mm in diameter), reniform basidiomata densely covered overall with white to pale yellow, erect, thick-walled, long hairs. It has melleous, echinulate basidiospores, and was found on fallen dead branches in lowland oak forests. (3) Crepidotus virgineus sp. nov. (section Crepidotus), forming pure white, reniform basidiomata, has smooth, ellipsoid basidiospores, subfusiform-pedicellate to irregularly cylindrical cheilocystidia, and abundant clamp connections. It occurs on fallen dead branches in lowland oak forests. Received: August 22, 2002 / Accepted: January 8, 2003 Acknowledgments I am grateful to Dr. Yousuke Degawa (KPM) for allowing the specimens cited to be kept in the Kanagawa Prefectural Museum of Natural History. Correspondence to:H. Takahashi     

<Emphasis Type="Italic">Exobasidium dubium</Emphasis> and <Emphasis Type="Italic">E. miyabei</Emphasis> sp. nov. causing Exobasidium leaf blisters on <Emphasis Type="Italic">Rhododendron </Emphasis>spp. in Japan

 Two Exobasidium species causing Exobasidium leaf blister on Rhododendron spp. are described. An Exobasidium leaf blister on Rhododendron yedoense var. yedoense f. yedoense has been recognized in Hokkaido Prefecture, Japan, since the first report was issued in 1950. The causal fungus is identified with Exobasidium dubium from the morphology of its hymenial structure and mode of germination of the basidiospores. Another Exobasidium leaf blister on Rhododendron dauricum has been observed in Hokkaido Prefecture, Japan. In comparison with morphology based on hymenial structure and mode of germination of the basidiospores of the 100 validly described taxa, this fungus differs from those known taxa in the size of basidia and basidiospores, the numbers of sterigmata and septa of basidiospores, and the mode of germination of basidiospores. Thus, a new species, Exobasidium miyabei, is established and illustrated. Received: February 13, 2002 / Accepted: September 25, 2002  Present address: National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan Acknowledgments We profoundly appreciate the cooperation of Dr. V. Melnik in providing Russian papers and Dr. L. Vasilyeva for translating them into English. We thank Prof. H. Takahashi for loaning the materials in the Herbarium of the Hokkaido University Museum and Dr. W. Abe, Graduate School of Science, University of Hokkaido, for his kind help with the sampling of R. dauricum in Teshikaga, Hokkaido Prefecture. This study was supported in part by a Grant-in-Aid for Scientific Research (B) (No. 13460019), Japan Society for the Promotion of Science (JSPS). Contribution No. 171, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba. Correspondence to:M. Kakishima     

<Emphasis Type="Italic">Hadrospora fallax</Emphasis> (Pleosporales) found in Japan

 Hadrospora fallax (Phaeosphaeriaceae, Pleosporales), collected from riverside environments, is described and illustrated for the first time in Japan. Received: December 13, 2002 / Accepted: January 27, 2003     

<Emphasis Type="Italic">Haliphthoros milfordensis</Emphasis> isolated from black tiger prawn larvae (<Emphasis Type="Italic">Penaeus monodon</Emphasis>) in Vietnam

 A marine fungus was isolated from the black tiger prawn Penaeus monodon at Nha Trang, Vietnam, on March 20, 2001 and named isolate NJM 0131. The fungus was identified as Haliphthoros milfordensis from the characteristics of asexual reproduction, and its physiological characteristics were investigated. Although the optimum temperature for growth of the isolate was 25°–30°C, the fungus grew at a wide range of temperatures (15°–40°C). H. milfordensis grew well in 50%–100% seawater, but poorly in PYG agar containing 1.0%–5.0% NaCl and KCl. The fungus grew at a wide range of pH (4.0–11.0) with the optimum pH value of 7.0–9.0. The isolate also showed pathogenicity to swimming crab larvae (Portunus trituberculatus) by artificial infection, but mortality was not high. This is the first report of disease in the black tiger prawn P. monodon in Vietnam caused by H. milfordensis. Received: July 22, 2002 / Accepted: January 21, 2003 Correspondence to:K. Hatai     

Masting of rowan <Emphasis Type="Italic">Sorbus aucuparia</Emphasis> L. and consequences for the apple fruit moth <Emphasis Type="Italic">Argyresthia conjugella</Emphasis> Zeller

 Masting of rowan Sorbus aucuparia L. has been studied in 45 sites in southern Norway for 22 years. We present data on the year-to-year variation in fruit setting of rowan, and show that masting is spatially synchronous in Norway and probably all over Fennoscandia. The apple fruit moth Argyresthia conjugella Zeller is an important seed predator on rowan. We present data on the abundance of apple fruit moth in rowanberries during these years and discuss the consequences of masting and intermasting of rowan for apple fruit moth as a pest of apple. We conclude that growth and climate have little impact on flowering intensity and suggest that masting of rowan is an adaptive defense against seed predation and a new example of predator satiation: intermast years inhibit predators and prepare the rowan for the subsequent mast. Received: September 3, 2001 / Accepted: February 24, 2003     

Chlamydospore formation of <Emphasis Type="Italic">Entoloma clypeatum</Emphasis> f. <Emphasis Type="Italic">hybridum </Emphasis>on mycorrhizas and rhizomorphs associated with <Emphasis Type="Italic">Rosa multiflora</Emphasis>

 Chlamydospores of Entoloma clypeatum f. hybridum were described on the mycorrhizas and rhizomorphs associated with Rosa multiflora. Their developmental pattern seems to be the Nyctalis type. This is the first report on chlamydospore formation on the mycorrhizae in entolomatoid fungi. Received: January 17, 2002 / Accepted: November 5, 2002 Acknowledgments K.H. is grateful to Emeritus Professor N. Sagara in Kyoto University, in whose laboratory part of this study was undertaken. Thanks are due to Mr. D. Sakuma for allowing the specimens to be kept in Osaka Museum of Natural History. Correspondence to:H. Kobayashi     

Hyaloscyphaceae in Japan (7): <Emphasis Type="Italic">Hyaloscypha albohyalina</Emphasis> var. <Emphasis Type="Italic">monodictys </Emphasis>var. nov.

 Hyaloscypha albohyalina var. monodictys, a new variety in the family Hyaloscyphaceae, Helotiales with Monodictys anamorph is described and illustrated. Received: June 26, 2002 / Accepted: July 27, 2002 Present address: Strategic Product Portfolio Department, Sankyo Co., Ltd., 3-5-1 Nihonbashi-Honcho, Chuo-ku, Tokyo 103-8426, Japan Tel. +81-3-5255-7040 (Ext. 2528); Fax +81-3-5255-7086 e-mail: hosoya@hq.sankyo.co.jp Correspondence to:T. Hosoya     

Methylmercury levels in a parasite (<Emphasis Type="Italic">Apophallus brevis</Emphasis> metacercariae) and its host,yellow perch (<Emphasis Type="Italic">Perca flavescens</Emphasis>)

The biomagnification of methylmercury (MeHg) amongst trophic levels results in high levels of this compound in many freshwater fish species. The role of parasites in MeHg cycling and trophic transfer in freshwater systems is largely unknown. This study examined the potential for metacercariae of Apophallus brevis to accumulate and biomagnify MeHg from their second intermediate host, yellow perch, Perca flavescens. Contrary to our prediction that MeHg levels would be higher in parasites than in the host muscle tissue in which they are embedded, we found that concentrations were similar. The lack of increase in MeHg levels from host to parasite may be due to limited assimilation of host muscle tissue or, in part, to low parasite metabolism. Parasite load did not reduce fish growth and subsequently alter MeHg concentrations. This study suggests that relationships between larval parasites and their hosts do not conform to typical patterns of MeHg biomagnification seen in aquatic systems.     

<Emphasis Type="Italic">Umbelopsis gibberispora</Emphasis> sp. nov. from Japanese leaf litter and a clarification of <Emphasis Type="Italic">Micromucor ramannianus </Emphasis>var. <Emphasis Type="Italic">angulisporus</Emphasis>

 Umbelopsis gibberispora is described as a new species in the genus Umbelopsis, Umbelopsidaceae, Mucorales. The species differs from others in this genus by ellipsoidal sporangiospores with unilaterally thickened walls. Phylogenetic analyses based on nuclear large subunit ribosomal DNA (nLSU rDNA) partial sequences suggest that U. gibberispora, U. swartii, and U. westeae form a clade together with the strains of Umbelopsis ramanniana. The ex-type strain of Micromucor ramannianus var. angulisporus is found to be very close to Umbelopsis vinacea, whereas other isolates identified under the former name in the sense of Linnemann fall in the U. ramanniana subclade. For these isolates, a new species, Umbelopsis angularis, is introduced. Phylogenetic relationships among Umbelopsis species are discussed related to their attributes of the sporangial wall and mature spore shapes. Received: August 27, 2002 / Accepted: March 11, 2003 Acknowledgments We thank Dr. Takashi Ohsono, Graduate School of Agriculture, Kyoto University, Japan, for providing the strain of U. gibberispora (CBS 109328). We also thank Dr. Wieland Meyer, University of Sydney, Australia for access to the phylogenetic tree based on ITS sequence data before publishing, and Dr. Richard C. Summerbell, Centraalbureau von Schimmelcultures, the Netherlands, for linguistic corrections.     

Diet changes in prey size selectivity in larvae of perch <Emphasis Type="Italic">Perca fluviatilis</Emphasis>

A hypothesis on change in prey size selectivity in relation to illumination level was tested on the basis of data on weight and size composition of the content of the digestive tract of larvae of perch Perca fluviatilis and on zooplankton in the layer 0–6 m (Wallersee Lake, Austria). Larvae foraging in the twilight-night period had almost two times more food in the intestine than those foraging in the daytime. The size composition of perch larvae and concentration and size composition of zooplankton hardly differed in the daytime and twilight-night samples. For the first time, it is shown on field material that more intensive feeding of larvae at twilight is related to selection of significantly larger prey than in daytime feeding. In the day-time, the larvae consumed more prey but their maximum size did not exceed 0.6 of the diameter of mouth opening of the fish; at twilight it was over 0.8. In case of feeding on so large prey, not only the weight of the consumed feed increases but the time used for capture and swallowing also considerably increases. The larvae which in the period of investigation did not yet form schools, which perform the principal defensive function, were especially vulnerable for predators feeding on relatively large prey. The decrease of the part of small-sized prey at twilight is not related to their lesser availability due to a low illumination. It is assumed that feeding on energetically more valuable but less available prey is shifted to the period of low illumination when the larvae are less exposed to predation risk. The obtained results are discussed from positions of the triotroph concept (Manteifel’, 1961).     

Variation in hydraulic architecture and gas-exchange in two desert sub-shrubs,<Emphasis Type="Italic"> Hymenoclea salsola</Emphasis> (T. &; G.) and<Emphasis Type="Italic"> Ambrosia dumosa</Emphasis> (Payne)

Adjustment of hydraulic architecture in response to environmental conditions was studied in two warm-desert sub-shrubs, Hymenoclea salsola and Ambrosia dumosa, both at the level of genetic adaptation along a climatic gradient and plastic response to immediate growth conditions. Individuals of both species originating from southern populations developed higher leaf-specific hydraulic conductance in the common greenhouse than individuals from northern populations. Hydraulic conductance was higher in plants grown at high temperature, but did not vary as a function of growth relative humidity. Hydraulic conductance was not correlated within species with individual variation in vessel diameter, cavitation vulnerability, or root:shoot ratio, but was strongly, negatively correlated with the fraction of total plant biomass allocated to leaves. For both species, stomatal conductance (g _s) at high leaf-to-air vapor pressure difference (ν) was tightly correlated with variability in hydraulic conductance, as was the sensitivity of stomatal closure to increasing ν. Experimentally increasing shoot water potential by soil pressurization, under conditions where high ν had already caused stomatal closure, led to substantial stomatal reopening in both species, but recovery was significantly higher in H. salsola. Hydraulic conductance was higher in H. salsola than A. dumosa. H.salsola also differed from A. dumosa by being a representative of a highly specialised group of desert shrubs which use the twigs as a major photosynthetic organ. The southern population of H. salsola produced far fewer leaves and relied much more heavily on twig photosynthesis than the northern population. At the whole-plant level, increased reliance on twig photosynthesis was associated with higher leaf-specific hydraulic conductance, but equivalent whole-plant photosynthesis on either a dry weight (μmol CO₂ g^–1) or nitrogen basis (μmol CO₂ g^–1)). This suggests that twig photosynthesis might be one way of increasing hydraulic conductance per unit photosynthetic canopy by increasing allocation to an organ which simultaneously performs photosynthetic, support, and transport functions. Received: 13 December 1999 / Accepted: 31 March 2000     

Pleosporales in Japan (1): the genus <Emphasis Type="Italic">Lophiostoma</Emphasis>

 Seven species of the genus Lophiostoma were the subject of this study. Among these, Lophiostoma mucosum is described and illustrated as a new species. All other species, L. macrostomum, L. semiliberum, L. arundinis, L. caulium, L. caudatum, and L. winteri, are reported for the first time in Japan. A key to the species of Lophiostoma in Japan is given. Received: August 5, 2002 / Accepted: November 28, 2002 Acknowledgments We are grateful to Dr. Hideki Takahashi (curator of SAPA) for the loan of fungal material. Correspondence to:Y. Harada     

Pleosporales in Japan (2): the genus <Emphasis Type="Italic">Lophiotrema</Emphasis>

 Five species of the genus Lophiotrema are reported in this article. Of these, Lophiotrema vitigenum is described and illustrated as a new species. Three species, L. nucula, L. neohysterioides, and L. vagabundum, are newly added to the Japanease mycoflora. Lophiosphaera orientalis, Nodulosphaeria araucariae, and N. rosae, which had been recorded in Japan, are treated as synonyms of Lophiotrema fuckelii. A key to the species of Lophiotrema in Japan is given. Received: October 9, 2002 / Accepted: January 20, 2003 Acknowledgments We are grateful to Drs. Shuhei Tanaka (curator of YAM) and Ken Katumoto for the loan of fungal material. Correspondence to:K. Tanaka     

Effects of <Emphasis Type="Italic">Acanthocephalus</Emphasis> sp. (Acanthocephala: Echinorhynchidae) on the body size and reproduction of isopods (<Emphasis Type="Italic">Asellus hilgendorfi</Emphasis>)

 Isopods Asellus hilgendorfi were collected from a small lake in northern Japan and examined to determine whether their body size and reproduction were affected by infection with larval acanthocephalans (Acanthocephalus sp.). Seasonal changes in the breeding ratio of isopods and the prevalence of larval acanthocephalan infection showed a reverse trend. Acanthocephalan larvae occurred mainly in males and immature females and were rarely found in mature females. In late immature females, the body size, as indicated by the width of the pleotelson, of infected isopods was significantly larger than that of uninfected ones. These results suggest that acanthocephalans can prevent female isopods from attaining sexual maturity and increasing their body size. Received: January 9, 2002 / Accepted: December 16, 2002 Acknowledgments We thank Professor Shōichi Saito, Faculty of Education, Hirosaki University, for his encouragement of the present study. Thanks are also due to the Iwasaki Village Office and the Fukaura Forestry Office for giving us permission for the survey. Correspondence to:A. Ohtaka