Don E. Hemmes

Origin and significance of the discharge vesicle in Phytophthora

During zoospore release from sporangia, all Phytophthora species studied developed a discharge (germination) vesicle into which 30 to 70% of the total number of zoospores were released before the vesicle burst. Vesicles of P. cactorum, P. Palmivora , and P. cinnamomi reached maximal diameters of 26, 40, and 46 μ m, respectively, when sporangia were placed in double-distilled water for zoospore release. The mean velocities of surface area enlargement of the vesicles represent ratios of 1:1.7:4.6, comparing P. cactorum with P. palmivora and with P. cinnamomi . For sporangia of P. cactorum , the surface area of the vesicle enlarged at a constant rate, whereas the increase in vesicle volume proceeded with an acceleration of about 79 μ m 3 /second 2 . When sporangia produced by P. cactorum grown in either bean meal broth or a chloride mineral solution were transferred to double-distilled water they developed discharge vesicles that enlarged in surface area at velocities of 224 and 145 μ m 2 /second, respectively, and had turgor pressures of about −8.0 and −4.8 bar, respectively. During zoospore release in P. palmivora , the outer sporangial wall and an amorphous cover layer were ruptured, and the papillar material (vesiculogen) was forced through the exit pore to form a continuous and plastic vesicle wall consisting of thin fibrillar elements of undetermined lengths (EM). The opening of the sporangium of P. palmivora , the enlargement of the vesicle, and subsequent zoospore release could be retarded or stopped in any stage by transferring germinating sporangia to CaCl 2 or PEG solutions with osmotic potentials between −2.5 and −3.5 bar. During plasmolytic treatments, the papillae of sporangia of P. cactorum and P. palmivora kept their original shape, whereas the apices of P. cinnamoni sporangia collapsed.

Xylaria moelleroclavus sp. nov. and its Moelleroclavus anamorphic state.

Moelleroclavus is considered to be an anamorphic genus. The teleomorph of M. penicilliopsis is shown through field observations, collection examination, and cultures to represent a previously unnamed species of Xylaria, X. moelleroclavus sp. nov. Xylaria lingua and X. scruposa are also discussed.

Ultrastructure of dormant, converted, and germinating oospores of Pythium ultimum

The ultrastructural aspects of the conversion of constitutively dormant oospores of Pythium ultimum to thin-walled germinable oospores and their subsequent germination were studied by electron micr...

Earthstars ( Geastrum, Myriostoma ) of the Hawaiian Islands Including Two New Species, Geastrum litchiforme and Geastrum reticulatum

Abstract: An updated, annotated list of earthstars found in the Hawaiian Islands is presented that includes 19 species of Geastrum and Myriostoma coliforme. Favored habitats for these gasteroid fungi include periodically wet windward coastal Casuarina groves, windward Leucaena thickets, and leeward coastal Prosopis groves. In contrast to these nonnative vegetation zones, earthstars such as Geastrum minimum, G. campestre, and G. corollinum are found also in largely native leeward montane Sophora/Myoporum forests, whereas Geastrum velutinum and G. reticulatum appear in montane native Acacia koa/Metrosideros forests. Eighty-two percent of the collections were made between September and February, although Geastrum triplex may be found earlier during the summer months. Two species, Geastrum litchiforme Desjardin & Hemmes and Geastrum reticulatum Desjardin & Hemmes, are described as new, accompanied by illustrations and comparisons with allied taxa. Geastrum xerophilum, originally published without Latin diagnosis, is formally validated. Specific collections are documented and island distribution and preferred habitats of the various species are listed. An artificial dichotomous key to aid in identification is provided.

Amanita marmorata subsp. myrtacearum?a new subspecies in Amanita section Phalloideae from Hawaii

A widely distributed Amanita was observed on six of the Hawaiian Islands fruiting in association with Eucalyptus and Casuarina species. Subsequent in? vestigation revealed it to be closely related to A. mar? morata subsp. marmorata. The holotype of A. marmorata was studied and found to be badly molded and mostly destroyed. Some anatomical details were visible and, though it is similar to our material, there are anatom? ical differences. The Hawaiian populations are also quite variable macroscopically and anatomically and, as a result, a new subspecies, A. marmorata subsp. myr? tacearum, is described for the Hawaiian Islands. A third taxon in this complex, A. reidii, recently described from South Africa, is discussed.

Agaricales of the Hawaiian Islands. 4: Hygrophoraceae

Seventeen taxa of Hygrophoraceae are re- ported from the Hawaiian Islands. Of these, six are new species, one a new variety and one a new form of Hygrocybe, two represent new species of Humidi- cutis; five represent first reports for the Hawaiian Is- lands; and two taxa are reported but not named be- cause of the lack of sufficient material for accurate taxonomic determination. Fifteen taxa are fully de- scribed, illustrated and compared with allied taxa. An artificial dichotomous key to Hawaiian Hygrophora- ceae is presented.

Agaricales of the Hawaiian Islands. 3: The genus Galerina and selected other brown-spored agarics

Three species of brown-spored agarics are described as new: Descolea alienata, Galerina ohiarum, and Pholiota peleae. In addition, six species of Galer? ina are first reports for the Hawaiian Islands. All spe? cies are described and compared with allied taxa, and most are illustrated with line drawings. An artificial dichotomous key to Hawaiian Galerina is presented.

Variability in the IGS1 region of Rhodocollybia laulaha: is it allelic, genomic, or artificial?

We tested the nuclear ribosomal intergenic spacer 1 (IGS1) to evaluate: 1) the utility of this gene region in the study of intra-lineage variation in the Hawaiian mushroom Rhodocollybia laulaha (Basidiomycota, Marasmiaceae); 2) the possibility of PCR-mediated artifacts from multiple cloned IGS1 inserts for five of the nine specimens included; and 3) the assignment of individual specimens to specific haplotype group genotypes. The IGS1 was sequenced for nine specimens of R. laulaha and multiple cloned copies of the IGS1 were sequenced for five of those nine to compare intra-specimen variation (i.e. among paralogous copies in a single genome) and inter-specimen variation (i.e. among different specimens). Three haplotype groups were identified with 25 of 510 aligned base pairs being variable (17 substitutions and eight indels). The observed variation could be due to the presence of various alleles of the IGS1 locus and/or variation among paralogous copies within a single genome. Issues associated with PCR error including artificial recombination and/or Taq error and the potential inefficiency of concerted evolution are considered as possible agents of variation.

Testing the “one-log-one-genet” hypothesis: methodological challenges of population sampling for the Hawaiian wood-decay fungus Rhodocollybia laulaha

We test our “one-log-one-genet” sampling method for the Hawaiian mushroom Rhodocollybia laulaha that posits all R. laulaha mushrooms collected from a single log represent a single genet. We also examine the potential expansion of single genets beyond the confines of one log and the temporal persistence of genets in nature. Finally, we estimate error rates in AFLP scoring. To our knowledge, this is one of few examinations of naturally occurring fungal genets in the tropics and a novel report of AFLP error rates in fungi. Forty-six mushrooms from seven logs were genotyped with the IGS1 locus, two microsatellite loci and 184 AFLP loci from three primer pair combinations. One hundred fifty-three mushroom collections representing the geographic range of R. laulaha were genotyped with the IGS1 and microsatellite loci. The probabilities of two genets sharing identical multilocus genotypes by chance (without actually being the same genet) were calculated for each genotype recovered. The data suggest that R. laulaha mushrooms from one log typically represent one genet, that genets might expand beyond the confines of a single log and that a single genet may persist in a collecting site for as much as 13 y. We offer initial evidence to support the “one-log-one genet” sampling method and the idea that R. laulaha vegetative expansion and persistence in nature might be common. In addition, we caution against exclusive use of AFLP loci for identifying fungal genets due to relatively high error rates in scoring.

A ruby-colored Pseudobaeospora species is described as new from material collected on the island of Hawaii

Pseudobaeospora wipapatiae is described as new based on material collected in alien wet habitats on the island of Hawaii. Unique features of this beautiful species include deep ruby-colored basidiomes with two-spored basidia, amyloid cheilocystidia and a hymeniderm pileipellis with abundant pileocystidia that is initially deep ruby in KOH then changes to lilac gray. Phylogenetic analysis of nuclear large ribosomal subunit sequence data suggest a close relationship between Pseudobaeospora and Tricholoma. BLAST comparisons of internal transcribed spacer and 5.8S nuclear ribosomal subunit regions sequence data reveal greatest similarity with existing sequences of Pseudobaeospora species. A comprehensive description, color photograph, illustrations of salient micromorphological features and comparisons with phenetically similar taxa are provided.