STUDIES OF PALEOZOIC FUNGI. I. THE STRUCTURE AND ORGANIZATION OF TRAQUAIRIA (ASCOMYCOTA)

Traquairia is one of the several unusual fungal structures occurring in Pennsylvanian coal balls. Specimens were initially described from European sediments and are now known from the Pennsylvanian of North America. Although Traquairia was originally believed to be a protozoan closely related to the radiolarians, its structure and organization suggest affinities with members of the fungal group, Ascomycota. Specimens are irregularly shaped and up to 1.0 mm in diameter. Each cleistothecium bears prominent radiating spines that are continuous with a peripheral mat of extensively branched, delicate hyphal filaments. A complex wall encloses a central cavity which may contain a number of asci with ascospores. Among extant fungi, Traquairia is most similar in form to members of the Eurotiales and Erysiphales.     

Transfer of <Superscript>14</Superscript>C-photosynthate to the sporocarp of an ectomycorrhizal fungus <Emphasis Type="Italic">Laccaria amethystina</Emphasis>

Sporocarps of ectomycorrhizal fungi are strong carbon sinks for the source in host trees, but the details of carbon transfer from the host to the sporocarp are unknown. In this study, single seedlings of Japanese red pine (Pinus densiflora) colonised by Laccaria amethystina were grown on floral foam plates fitted in rhizoboxes, resulting in fruiting on the substrate. The seedlings were photosynthetically labelled with ¹⁴CO₂; ¹⁴C-labelled photosynthate transfer from leaves to sporocarps was then chased using a time-course autoradiography technique. ¹⁴C was transferred to healthy, fresh sporocarps in a purple colour ranging from primordial to elongate sporocarps, but hardly to senesced ones that had faded to white or grey, or browned. This suggested that C is transferred only to physiologically active sporocarps. Two seedlings associated with a growing sporocarp were labelled again 7 and 16 days after the first labelling, respectively. ¹⁴C accumulation in the sporocarps rose in a stepwise manner after the second labelling, indicating that sporocarps mainly used recently rather than previously photosynthesised C.     

Sporocarp ontogeny in Panus (Basidiomycotina): evolution and classification

Ontogenies of cultured Panus conchatus, P. rudis, and P. fulvus sporocarps were observed macroscopically and with scanning electron microscopy. Hymenophore differentiation in Panus involves periclinal growth of context hyphae below a closed surface palisade of hymenial elements, resulting in a cantharelloid appearance and radiate trama. This pattern is qualitatively different from that in Lentinus s. str., which suggests that lamellae of Panus and Lentinus are not homologous. Panus conchatus and P. rudis sporocarps have short stipes, develop directly from the mycelium, and mature in 5–10 d. Panus fulvus sporocarps have an elongate stipe, develop from a pseudosclerotium, and mature in about 3 wk, the first approximately 15 d of which involve apical elongation of a stipelike primordium that is able to dedifferentiate and regenerate cut apices. Panus conchatus and P. rudis sporocarps lacked regeneration ability. Panus conchatus sporocarps developed an ephemeral partial veil that was obliterated during sporocarp expansion. Outgroup comparison suggests that evolutionary changes in developmental programs in Panus have included: 1) delay in offset of primordium growth, with a corresponding increase in primordium size and time to maturation (hypermorphosis); 2) insertion of the pseudosclerotial stage in ontogeny; 3) gain of ability for dedifferentiation and regeneration; and 4) nonterminal gain or loss of veil tissue.     

Genet Distribution of Ectomycorrhizal Fungus Suillus grevillei Populations in Two Larix kaempferi Stands over Two Years

Suillus grevillei in two Larix kaempferi stands was determined over two years by inter-simple sequence repeat (ISSR) polymorphism analysis using primers, (GTG)₅, (GCC)₅ and (GACA)₄. Thirty-five genets were identified from 67 sporocarps at the older stand (stand A in which the distribution of S. grevillei genet in 1997 was analyzed previously) in 1998, and 14 genets from 52 sporocarps at the younger stand (stand B) in 1997 and 1998. The characteristics of S. grevillei genets in stand A in 1998 were similar to those in 1997. A single genet was represented by 1.8 and 3.7 sporocarps on average in stands A and B, respectively. In stand A, 42 out of 61 genets, i.e., about 70% were represented by individual sporocarps compared to five out of 14 genets, i.e., about 35% in stand B. The largest and the average genet sizes was 6.8 m and less than 1 m in stand A, and 11 m and 2.3 m in stand B, respectively. A t-test showed the genet size in stand A to be significantly smaller than that in stand B. The above results indicate that the smaller genets of the S. grevillei population in stand A might be due to environmental conditions not genetic traits specific to this species. Observations over two years showed that although some genets formed sporocarps in both 1997 and 1998, many formed sporocarps only in one of the two years. Emerging positions of sporocarps in 1997 and 1998, which belonged to the same genet, were similar but not identical, about 2 m apart, suggesting mobility in the subterranean parts of ECM fungal genets. Received 10 April 2000/ Accepted in revised form 31 August 2000     

ULTRASTRUCTURE AND TAXONOMIC POSITION OF THE RARE VOLVOCALEAN ALGA,CHLORCORONA BOHEMICA1

Chlorcorona bohemica (Fott) Fott was previously of uncertain taxonomic affinities. The cell to cell connections, which are one of the chief features of the colony, are composed of wall extensions from adjacent cells. The outgrowths are connected by a fine fibrous component extending from wall to wall. The structure of the wall itself and the cell to cell connections, are similar to those of Pyrobotrys, although the connections in the latter are not as elongated. In addition, the flagellar apparatus of Chlorocorona is very similar to the flagellar apparatus of Pyrobotrys, and unlike that in other Chlorophyceae examined. These features suggest that Chlorcorona is closely related to Pyrobotrys and should be referred to the family Spondylomoraceae.     

Dispersed cuticles of putative non-vascular plants from the Lower Devonian of Britain

Dispersed cuticles with surface ornamentation recovered from the Lower Old Red Sandstone (Gedinnian) of Hereford and Worcester, England, are described, named and placed in an artificial, morphologically based classification system. Four species of the new genus Cosmochlaina are distinguished on the nature of the ornament. The affinities of the plants covered by such cuticles remain unknown: the cuticles are named to facilitate their use in biogeographic, stratigraphic and evolutionary studies.     

Insect feeding on spores of a bracket fungus, Elfvingia applanata (Pers.) Karst. (Ganodermataceae, Aphyllophorales)

Insects visiting sporocarps of Elfvingia applanata, a wood-rotting bracket fungus, were examined in Kyoto, central Japan. Mycodrosophila flies (Drosophilidae: Diptera) were predominant and visited the spore-producing sporocarps exclusively. They were observed feeding on the spores, and a number of spores seemed to be alive even after having passed through insects digestive tracts. In addition, the insects attached a number of spores on their body surfaces. In a rearing experiment with insects caught from E. applanata sporocarps, Mycodrosophila flies excreted 7700–469 000 and dropped 10–000–329 000 of viable spores during 48 h after collection. They were supposed to migrate among the sporocarps of other bracket fungi growing on different logs or stumps, suggesting that Mycodrosophila flies may act as spore-dispersal agents for E. applanata.     

Molecular approaches to ectomycorrhizal diversity studies: variation in ITS at a local scale

In most ectomycorrhizal (EM) community studies involving molecular identification methods there is a poor correspondence between fungi that appear dominant as sporocarps and those that appear dominant on EM roots and the species richness belowground is higher than that above ground. As a consequence, many fungi from root tip samples remain unidentified. In most studies, genetic data from multiple samples of an EM morphotype collected from various sampling locations are compared to genetic data from one to a few sporocarps of each species for identification purposes. The mismatch between above- and belowground species richness may be influenced by these different sampling efforts. To address this, intra-specific variation in the ITS region first investigated in Kårén et al. (1997) is revisited here, but at a spatial scale in which variation is expected to be low. Sporocarps were collected across a 7 km region of the Oregon Dunes National Recreation Area in western North America. ITS–RFLP data are presented for 3-18 sporocarps from each of 44 EM species in 18 genera. A total of 311 sporocarps were analyzed. Fifty-three ITS–RFLP types were observed. Of the 44 species, 38 (86% of total) yielded a single, species specific, RFLP type. No 2 species had the same RFLP type. Polymorphic ITS–RFLP types were observed in six species (14%). The following three species had two ITS-RFLP types with one type dominating: Inocybe lacera, Laccaria proxima, and Rhizopogon subcaerulescens. The following three species had three RFLP types with no type dominating: Laccaria laccata, Lactarius deliciosus, and Tricholoma flavovirens. A phylogenetic analysis of ITS sequences in Tricholoma revealed that two of the RFLP types in T. flavovirenswere apparently the result of intra-specific variation, while the third RFLP type was likely a cryptic species. All the other RFLP types observed in Tricholoma represented unique phylogenetic species. These results suggest that ITS–RFLP data from single samples (sporocarp or EM) are robust for characterizing most of the species at this scale. However, restriction endonucleases detect a limited amount of existing nucleotide variation and thus have limited value to detect cryptic species. Therefore, additional analyses of sequence data should be added to the RFLP matching technique to identify unknown RFLP types. These data also suggest that polymorphic RFLP types within species do not adequately explain the mismatch between above- and belowground views of EM species richness.     

Mycophagy by small mammals in the coniferous forests of North America: nutritional value of sporocarps of Rhizopogon vinicolor, a common hypogeous fungus

We evaluated the nutritional value of sporocarps of Rhizopogon vinicolor, a common hypogeous fungus in the coniferous forests of North America, for two small mammal species: the Californian red-backed vole (Clethrionomys californicus) and the northern flying squirrel (Glaucomys sabrinus). Although the nitrogen concentration of sporocarps was high, much of it was in non-protein form or associated with cell walls, suggesting that it may be of low nutritional value or protected from mammalian digestive enzymes. Sporocarps also had high concentrations of cell wall constituents, indicating low availability of digestible energy. When fed a diet of this fungus alone in a controlled feeding experiment both mammal species lost a small amount of body mass. Digestibilities of dry matter, nitrogen, cell wall constituents and energy from sporocarps by both species were lower than the digestibilities of other food types by other similarly sized small mammals. Red-backed voles digested the various components of sporocarps at least as well as the flying squirrels, even though they were almost six-fold smaller in body mass. This observation supports the notion that red-backed voles, like other microtine rodents, have morphological and physiological adaptations of the digestive system that are postulated to permit greater digestion of fibrous diets than predicted on the basis of body size. Despite this, our results re-affirm previous conclusions that hypogeous fungi are only of moderate nutritional value for most small, hindgut-fermenting mammals. Future studies should focus on the importance of mixed-species of fungi in the diet of small mammalian mycophagists. Accepted: 4 December 1998     

Population structure of Guyanagaster necrorhizus supports termite dispersal for this enigmatic fungus

Understanding how species accomplish dispersal of their propagules can shed light on how they are adapted for their ecosystem. Guyanagaster necrorhizus is a sequestrate fungus, meaning its dispersal propagules, or spores, are entirely enclosed within a fruiting body, termed a sporocarp. This fungus is most closely related to Armillaria and its allies. While Armillaria species form mushrooms and have forcibly discharged spores, G. necrorhizus spores have lost this ability, and by necessity, must be passively dispersed. However, G. necrorhizus does not possess characteristics of other sequestrate fungi with known dispersal mechanisms. Repeated observations of termites feeding on G. necrorhizus sporocarps, and spores subsequently adhering to their exoskeletons, led to the hypothesis that termites disperse G. necrorhizus spores. To test this hypothesis, we used microsatellite markers and population genetics analyses to understand patterns of clonality and population structure of G. necrorhizus. While Armillaria individuals can spread vegetatively over large areas, high genotypic diversity in G. necrorhizus populations suggests spores are the primary mode of dispersal. Spatial genetic structure analyses show that G. necrorhizus sporocarps within 238 m of each other are more closely related than would be expected by chance and conservative estimates from population assignment tests suggest gene flow no longer occurs between sporocarps separated by 2 km. These distances are consistent with previous studies analysing foraging distances of the termites found associated with G. necrorhizus sporocarps. Termites have rarely been recorded to specifically target fungal sporocarps, making this a potentially novel fungal–insect interaction.     

Negative stain in wax tubes from the surface of Sitka spruce leaves

Summary Carbon replicas and scanning electron micrographs of wax outgrowths on some leaf surfaces have not shown conclusively whether the outgrowths are tubes or solid rods. Some workers have suggested that they are solid rods. We find that negative stains will penetrate into a cavity in the centre of wax outgrowths on leaves of Sitka spruce (Picea sitchensis Bong. Carr) and Tulipa kaufmanniana Elliot. Thus these outgrowths appear to be tubes.     

The secotioid form of Lentinus tigrinus: genetics and development of a fungal morphological innovation

Secotioid fungi resemble gasteromycetes, but are presumably closely related to agaricoid fungi. Lentinus tigrinus is a wood-decaying mushroom that has both a secotioid and an agaricoid form. We examined ontogeny and heritability of the secotioid phenotype in L. tigrinus with a combination of formal genetic crosses, scanning electron microscopy, and macroscopic observation of cultured sporocarps. For F1 analysis, we crossed single-spore isolates (SSIs) representing four mating types derived from a secotioid dikaryon and four mating types from an agaricoid dikaryon. All F1 sporocarps had typical agaricoid morphology. For F2 analysis, 200 SSIs from one F1 sporocarp and 100 SSIs from another F1 sporocarp were backcrossed to tester SSIs from sporocarps produced by the parental secotioid dikaryon. Ratios of secotioid to agaricoid dikaryons thus produced were 47:49 and 84:109, which confirms previous reports that the secotioid phenotype is conferred by a recessive allele at a single locus (χ² = 0.0417, P > 0.05, χ² = 3.2383, P > 0.05, respectively). Early ontogeny of the secotioid form is indistinguishable from that of the agaricoid form. Later, the hymenophore is obscured by a weft of hyphae that proliferates from the margins of the developing lamellae. Longevity of the sporocarps and rate and duration of sporocarp growth are approximately equal in the secotioid and agaricoid forms. Developmental evolution of the secotioid form is interpreted as an example of von Baerian differentiation, rather than paedomorphosis, which has been implicated in evolution of other secotioid taxa.     

A molecular survey of ectomycorrhizal hyphae in a California Quercus–Pinus woodland

Ectomycorrhizal (ECM) hyphal communities have not been well characterized. Furthermore, there have been few studies where the ECM hyphal community is compared to fungi detected as sporocarps or ECM-colonized root tips. We investigated fungi present as hyphae in a well-studied California Quercus–Pinus woodland. Hyphal species present were compared to those found as sporocarps and ECM root tips at the same site. Hyphae were extracted from root-restrictive nylon mesh in-growth bags buried in the soil near mature Quercus douglasii, Quercus wislizeni, and Pinus sabiniana. Taxa were identified using PCR, cloning, and DNA sequencing of internal transcribed spacer and 28s rDNA. Among the 33 species detected, rhizomorph-forming ECM fungi dominated the hyphal community, especially species of Thelephoraceae and Boletales. Most fungi in soils near Quercus spp. and P. sabiniana were ECM basidiomycetes, but we detected two ECM ascomycetes and three non-mycorrhizal fungi. Many ECM species present as hyphae were also previously detected at this site as sporocarps (18%) or on ECM root tips (58%). However, the hyphal community was mostly dominated by different taxa than either the sporocarp or ECM root communities.     

Evidence for a fungal affinity for Nematasketum,a close ally of Prototaxites

As part of a project investigating diversity in early terrestrial vegetation, new specimens of the enigmatic, non‐embryophyte Nematasketum diversiforme have been described from Lower Devonian strata in the Welsh Borderland to elucidate its affinities and role in the ecosystem. Charcoalified fragments were investigated using scanning electron microscopy. They show for the first time that at least part of the organism possessed an axial organization with a peripheral zone forming a rind. The specimens differ from the closely‐allied Prototaxites by the presence of unevenly thickened tubes, both in well‐defined areas (medullary spots), hypothesized as being the sites of hyphal generation, and in the matrix of wide, smooth‐walled and narrow hyphae. Two specimens that show branching but no unequivocal thickened tubes are best assigned to the prototaxalean complex. The fragments, with longitudinally aligned wide tubes in a matrix of much branched, narrower examples, resemble rhizomorphs and cords of extant basidiomycote fungi and are interpreted as exploratory and translocating organs. Postulated affinities of Prototaxites include algae, fungi and hepatics, with the latter interpreting the fossils as rolled‐up liverwort mats. Our studies on a close ally of Prototaxites show no evidence for hepatic affinity, although similarities with fungal linear mycelial structures. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 1–18.     

Spatial Distribution of the Subterranean Mycelia and Ectomycorrhizae of Suillus grevillei Genets

Suillus grevillei , and found that one, SG-5, is species-specific to S. grevillei and polymorphic. Using the SG-5 marker, we analyzed for the first time the horizontal and vertical distribution of the subterranean parts of several S. grevillei genets. The spatial distribution of S. grevillei genets in the soil demonstrated that the development of S. grevillei sporocarps is correlated with that of extra-radical mycelia and ectomycorrhizae of the same genet, which are distributed in a narrow area. However, sporocarps are not always centered over the subterranean parts and the amount of subterranean mycelia and mycorrhizae is not always correlated to the number of sporocarps formed on them. No S. grevillei mycelia and mycorrhizae were detected beneath the positions where S. grevillei sporocarps emerged in the previous year. The observation indicates the rapid alteration of the subterranean parts of S. grevillei genets, and suggests that S. grevillei genets change location rather than merely extend their habitat year after year. Received 13 October 2000/ Accepted in revised form 15 March 2001     

Ectomycorrhizal fungal communities of native and non-native Pinus and Quercus species in a common garden of 35-year-old trees

Non-native tree species have been widely planted or have become naturalized in most forested landscapes. It is not clear if native trees species collectively differ in ectomycorrhizal fungal (EMF) diversity and communities from that of non-native tree species. Alternatively, EMF species community similarity may be more determined by host plant phylogeny than by whether the plant is native or non-native. We examined these unknowns by comparing two genera, native and non-native Quercus robur and Quercus rubra and native and non-native Pinus sylvestris and Pinus nigra in a 35-year-old common garden in Poland. Using molecular and morphological approaches, we identified EMF species from ectomycorrhizal root tips and sporocarps collected in the monoculture tree plots. A total of 69 EMF species were found, with 38 species collected only as sporocarps, 18 only as ectomycorrhizas, and 13 both as ectomycorrhizas and sporocarps. The EMF species observed were all native and commonly associated with a Holarctic range in distribution. We found that native Q. robur had ca. 120% higher total EMF species richness than the non-native Q. rubra, while native P. sylvestris had ca. 25% lower total EMF species richness than non-native P. nigra. Thus, across genera, there was no evidence that native species have higher EMF species diversity than exotic species. In addition, we found a higher similarity in EMF communities between the two Pinus species than between the two Quercus species. These results support the naturalization of non-native trees by means of mutualistic associations with cosmopolitan and novel fungi.     

Three-dimensional anatomy of the Tully monster casts doubt on its presumed vertebrate affinities

Tullimonstrum gregarium, also known as the Tully monster, is a well-known phylogenetic enigma, fossils of which have been found only in the Mazon Creek Lagerstätte. The affinities of Tullimonstrum have been debated since its discovery in 1966, because its peculiar morphology with stalked eyes and a proboscis cannot easily be compared with any known animal morphotypes. Recently, the possibility that Tullimonstrum was a vertebrate has attracted much attention, and it has been postulated that Tullimonstrum might fill a gap in the fossil record of early vertebrates, providing important insights into vertebrate evolutionary history. With the hope of resolving this debate, we collected 3D surface data from 153 specimens of Tullimonstrum using a high-resolution laser 3D scanner and conducted x-ray micro-computed tomographic (μCT) analysis of stylets in the proboscis. Our investigation of the resulting comprehensive 3D morphological dataset revealed that structures previously regarded as myomeres, tri-lobed brain, tectal cartilages and fin rays are not comparable with those of vertebrates. These results raise further doubts about its vertebrate affinities, and suggest that Tullimonstrum may have been either a non-vertebrate chordate or a protostome.     

Biomass and nutrient concentrations of sporocarps produced by mycorrhizal and decomposer fungi in Abies amabilis stands

Summary Sporocarps and sclerotia were collected for a one-year period in 23- and 180-year-old Abies amabilis stands in western Washington. All sporocarps were classified and chemically analyzed for N, P, K, Ca, Mg, Na and Fe. Lactarius sp. and Cortinarius sp. contributed the largest proportion of the total annual epigeous sporocarp production in both stands. Annual epigeous production was 34 kg/ha in the young stand and 27 kg/ha in the mature stand. Hypogeous sporocarp production increased from 1 kg ha^-1 yr^-1 to 380 kg ha^-1 yr^-1 with increasing stand age. High sclerotia biomass occurred in the young (2,300 kg/ha) and mature (3,000 kg/ha) stands. Peak sclerotia and epigeous sporocarp biomass in the young stand and epigeous and hypogeous sporocarp biomass in the mature stand coincided with the fall peak of mycorrhizal root biomass.In the young stand, sporocarps produced by decomposer fungi concentrated higher levels of Ca and Mn than those produced by mycorrhizal fungi. In the mature stand, sporocarps of decomposer fungi concentrated higher levels of N, P, Mn, Ca and Fe than sporocarps of mycorrhizal fungi. Epigeous and hypogeous sporocarps concentrated higher levels of N, P, and K than sclerotia or mycelium. The highest concentration of N (4.36%), P (0.76%), K (3.22%) and Na (1,678 ppm) occurred in epigeous sporocarps. Highest Mn (740 ppm) and Ca (20,600 ppm) concentrations occurred in mycelium, while highest Mg (1,929 ppm) concentrations were in hypogeous sporocarps and highest Fe (4,153 ppm) concentrations were in sclerotia.