John C. Landolt

Mycorrhizae from Denali National Park and Preserve, Alaska

Abstract Roots of 40 taxa of higher plants (Pteridophyta, Spermatophyta) from two alpine study sites in Denali National Park and Preserve in central Alaska were examined for their mycorrhizal colonization. We observed ectomycorrhizae on six species: Betulanana, Salixreticulata, Salixpolaris, Salixarctica, Polygonumviviparum, and Dryasoctopetala. Seven taxa, Cassiopetetragona, Empetrumnigrum, Ledumpalustre subsp. decumbens, Ledumpalustre subsp. groenlandicum, Loiseleuriaprocumbens, Vacciniumuliginosum and Vacciniumvitis–idaea (all Ericales), had ericoid mycorrhizae. One species, Arctostaphylosalpina, formed a typical arbutoid mycorrhiza. Two species (Sibbaldiaprocumbens and Aconitumdelphinifolium) showed well-developed VA mycorrhizae, whereas three species of plants (Lycopodiumclavatum, Sileneacaulis and Oxytropisscammaniana) had vesicles, but no arbuscules. The roots of 11 other plants (Lycopodiumclavatum, Lycopodiumselago, Sileneacaulis, Gentianaalgida, Lupinusarcticus, Oxytropisscammaniana, Pedicularislangsdorffii, Pediculariscapitata, Pedicularisverticillata, Artemisia sp. and Carexbigelowii) had a variety of intracellular colonizations which are referred to as dark septate fungi. No mycorrhizae were found on 12 other plants: Equisetumarvense, Equisetumvariegatum, Lycopodiumalpinum, Polygonumbistorta, Saxifragahieracifolia, Saxifragahirculus, Astragalusalpinus, Pediculariskanei, Petasitesfrigidus, Carexpodocarpa, Carexmicrochaeta and Poaarctica. A possible ecological role of dark septate fungi is discussed.

Protostelids, dictyostelids, and myxomycetes in the litter microhabitat of the Luquillo Experimental Forest, Puerto Rico

Protostelids, dictyostelids and myxomycetes are well known from terrestrial ecosystems in temperate regions but poorly known from the tropics. This study examined the distribution and ecology of these three groups of ‘slime moulds’ in the forest floor litter microhabitat of five different forest types (tabonuco forest, secondary tabonuco forest, palo colorado forest, palm forest, and elfin forest) within the Luquillo Experimental Forest in Puerto Rico. Protostelids associated with aerial litter (dead but still attached plant parts) also were studied. At least 13 species of protostelids, 13 species of dictyostelids and 24 species of myxomycetes were recovered. Both species richness and abundance of dictyostelids and myxomycetes were higher in the secondary tabonuco forest than in any of the other forest types. The tabonuco forest yielded the most species of protostelids, but the next highest total was recorded from the secondary tabonuco forest. Both of these forest types are located at the low end of the elevation gradient. Lowest levels of species richness and abundance occurred in the elfin forest, located at the high end of the elevation gradient. The general pattern observed was that of decreasing diversity with increasing elevation.

An expanded phylogeny of social amoebas (Dictyostelia) shows increasing diversity and new morphological patterns

BackgroundSocial Amoebae or Dictyostelia are eukaryotic microbes with a unique life cycle consisting of both uni- and multicellular stages. They have long fascinated molecular, developmental and evolutionary biologists, and Dictyostelium discoideum is now one of the most widely studied eukaryotic microbial models. The first molecular phylogeny of Dictyostelia included most of the species known at the time and suggested an extremely deep taxon with a molecular depth roughly equivalent to Metazoa. The group was also shown to consist of four major clades, none of which correspond to traditional genera. Potential morphological justification was identified for three of the four major groups, on the basis of which tentative names were assigned.ResultsOver the past four years, the Mycetozoan Global Biodiversity Survey has identified many new isolates that appear to be new species of Dictyostelia, along with numerous isolates of previously described species. We have determined 18S ribosomal RNA gene sequences for all of these new isolates. Phylogenetic analyses of these data show at least 50 new species, and these arise from throughout the dictyostelid tree breaking up many previously isolated long branches. The resulting tree now shows eight well-supported major groups instead of the original four. The new species also expand the known morphological diversity of the previously established four major groups, violating nearly all previously suggested deep morphological patterns.ConclusionsA greatly expanded phylogeny of Dictyostelia now shows even greater morphological plasticity at deep taxonomic levels. In fact, there now seem to be no obvious deep evolutionary trends across the group. However at a finer level, patterns in morphological character evolution are beginning to emerge. These results also suggest that there is a far greater diversity of Dictyostelia yet to be discovered, including novel morphologies.

Vertebrates as vectors of cellular slime moulds in temperate forests

Nine species of dictyostelid cellular slime moulds were isolated from the faecal material of a number of different vertebrates, including several rodents and a terrestrial salamander, that are common and widespread inhabitants of temperate forests in eastern North America. Their presence suggests that vertebrates may play a role in short to medium range dispersal of these organisms.

Dictyostelid cellular slime moulds in the forests of New Zealand

Abstract During the period of February to April of 1998, soil/litter samples for isolation of dictyostelid cellular slime moulds were collected throughout New Zealand. Collecting sites included examples of main forest types found in the country and a range in latitude (35°S to 47°S) that encompassed most of New Zealand. Thirteen species of dictyostelids were recovered; all of these occurred at low frequencies and densities. This total included a number of species (e.g., Dictyostelium mucoroides and Polysphondylium violaceum) that are common and widespread throughout the Northern Hemisphere as well as several other species that have a more restricted distribution. Among the latter are Dictyostelium fasciculatum, not previously known outside of Europe, and D. rosarium, previously reported from only a few scattered localities in the Northern Hemisphere. Five of the species recovered (D. antarcticum, D. australe, D. leptosomum, D. quercibrachium, and P. anisocaule) are described for the first time. New Zealand is the most isolated land mass of its size in the world, and the assemblage of dictyostelids present is quite distinctive and seems to reflect this isolation.

Didymium iridis reproductive systems: additions and meiotic drive

Three heterothallic Mexican isolates (Mex 1, Mex 2, and Mex 3) of Didymium iridis belong to the reproductively isolated A5 mating series of this morphospecies. This was unexpected in that the sole previous A5 isolate was from Georgia and the Mexican isolates were collected in southern Mexico adjacent to the Central American Al series region. The Mexican isolates were also unusual in that mating alleles did not generally segregate in a normal 1:1 ratio. The A53 or A54 mating types, when present in a plasmodium, caused the partial or total elimination ofthe other mating allele during growth or sporulation. Isolates from Guatemala (Gua 2) and Panama (Pan 8) were found to belong to the Central American Al mating series. Each of these isolates was collected as a haploid selfed plasmodium which contained a single mating type respectively designated Al13 and Al14. Four nonheterothallic isolates from California (Ca 8), Guatemala (Gua 1), Japan (Jap 1) and South Africa (SA 2) were also investigated.

CELLULAR SLIME MOLDS IN WEST VIRGINIA CAVES INCLUDING NOTES ON THE OCCURRENCE AND DISTRIBUTION OF DICTYOSTELIUM ROSARIUM

Twenty-three caves in West Virginia were investigated for the presence of dictyostelid cellular slime molds. Nine species were recovered, but only three of these (Dictyostelium sphaerocephalum, D. mucoroides, and D. rosarium) were recorded from at least 10 different caves. In general, the distribution of cellular slime molds in caves appears to be rather patchy, but in the microsites where they do occur, these organisms exhibit surprisingly high levels of abundance and diversity. The presence of D. rosarium in West Virginia caves was unexpected, since this species has not yet been recorded from aboveground sites in the state. Previous reports of the occurrence and distribution of D. rosarium indicate that the species is most commonly associated with moderately dry or saline soils in arid habitats. However, the results of the present study suggest that D. rosarium is also able to exploit cave habitats to a greater extent than most other cellular slime mold species.

Cellular Slime Molds in Forest Soils of West Virginia

A study of occurrence and distribution of cellular slime molds (CSM) in forest soils of West Virginia was carried out. Samples for CSM isolation were collected from 21 study sites, including exampl...

New species of dictyostelid cellular slime moulds from Australia

During the 2001–2006 field seasons, samples for isolation of dictyostelid cellular slime moulds were collected at several localities in Queensland, the Northern Territory, Western Australia and Victoria. The majority of these samples were collected from the soil–litter layer on the ground, but some additional samples were obtained from the layer of organic matter (‘canopy soil’) associated with the bases of vascular epiphytes on the trunks and branches of trees in the tropical forests of northern Queensland. Many of the forms recovered from these samples could be assigned to described taxa, including such cosmopolitan species as Dictyostelium mucoroides, Polysphondylium pallidum, P. violaceum and D. giganteum. However, several others appear to represent new species, and eight of these (D. boomeransporum, D. flexuosum, D. granulosum, D. myxobasis, D. radiculatum, D. rotatum, P. australicum and P. stolonicoideum) are described herein. The large number of apparently undescribed forms suggests that the dictyostelid biota of Australia is relatively distinct when compared with that of any other continent.

Two new species of dictyostelid cellular slime molds from Alaska

In sampling soils to survey dictyostelid cellular slime molds in Alaska we encountered two groups of isolates that have morphologies that differ from any previously described species within their group. We sequenced the nuclear small subunit ribosomal RNA gene (SSU rDNA) of selected isolates from the two groups and found sequences from both groups to be distinct from all previously described dictyostelid sequences. Phylogenetic analyses place one novel species in dictyostelid Group 2 and the other in Group 4 (Schaap et al. 2006). In this paper we formally describe as new these two species of cellular slime molds, Dictyostelium ammophilum sp. nov. and Dictyostelium boreale sp. nov., based on the combination of morphological and molecular characters.