A tale of two clades: Comparative study of Glyptodon Owen and Glyptotherium Osborn (Xenarthra,Cingulata, Glyptodontidae)

Glyptodon and Glyptotherium represent the most conspicuous taxa of late Neogene and Pleistocene glyptodonts in South America and North America, respectively. The earliest records of Glyptodon in South America are 1.07 Ma (late early Pleistocene, Calabrian), although the possibility that “Paraglyptodon uquiensis” represents a Pliocene specimen of Glyptodon cannot be rejected. Glyptotherium originated from South American ancestry in northern South America or Central America about 3.9 Ma (early late Pliocene, Zanclean) or earlier. The diversity of South American Glyptodon is currently under study, but preliminary evidence would indicate that no more than three species (G. munizi, G. elongatus and G. reticulatus) are valid, plus a possible new Andean species. In turn, according to the updated taxonomy proposed herein, Glyptotherium includes two chronospecies. The earliest species, Gl. texanum, differs only slightly from the latest species, Gl. cylindricum. The relationship of Glyptodon and Glyptotherium has been problematical since the discovery of the North American lineage, at first identified as various species of Glyptodon and later considered a separate genus. Glyptodon is recognized as a natural group and recent taxonomic and phylogenetic revisions place all North American glyptodontines into Glyptotherium. In this paper, we propose a detailed morphological comparison between the southern South American species of Glyptodon and Glyptotherium in order to identify diagnostic differences and potential synapomorphies. Both genera can be distinguished mainly by differences in the skull, mandible, dentition, dorsal carapace, and caudal armor, Glyptodon being somewhat larger than Glyptotherium. Both clades show a highly conservative evolution, which could be interpreted as an anagenesis. The scarce records of glyptodonts in Central America show more morphological affinity with Glyptotherium than with Glyptodon.     

Gambierdiscus species exhibit different epiphytic behaviors toward a variety of macroalgal hosts

Ciguatera fish poisoning is a common form of seafood poisoning caused by toxins (ciguatoxins) that accumulate in demersal (reef) food webs. The precursors of ciguatoxins are produced by dinoflagellates of the genus Gambierdiscus, and enter the food web via herbivory and detritivory. The Gambierdiscus genus was recently revised and new research on the physiology and ecology of the revised species is needed. While it has been demonstrated that Gambierdiscus spp. are predominately epiphytic, the variability in epiphytic behavior among the various Gambierdiscus species is not known. Five Gambierdiscus species isolated from the Greater Caribbean Region were the focus of this study (G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri, and G. yasumotoi). Cells of Gambierdiscus were grown in wells with algae fragments from eight different macroalgal host genera (Acanthophora, Caulerpa, Dasya, Derbesia, Dictyota, Laurencia, Polysiphonia, and Ulva) where the epiphytic behavior and growth of the different Gambierdiscus species were monitored over 29 days. The results of this experiment demonstrate that epiphytic behavior (growth and attachment) differs among the Gambierdiscus species toward the various macroalgal hosts. Results tended to be specific to Gambierdiscus – host pairings with few commonalities in the way a particular Gambierdiscus species interacted across hosts or how the various Gambierdiscus species responded to a particular host. The Gambierdiscus – host pairings that resulted in the highest growth and attachment combinations were examined in terms of known cellular toxicity and host palatability to determine which pairings could represent the most likely vectors for the transfer of ciguatoxins (or precursors) into the demersal food web. Two pairings, Gambierdiscus belizeanus – Polysiphonia and G. belizeanus – Dictyota, best met these criteria, providing a hypothetical approach to better focus sampling and monitoring efforts on such potential vectors in the benthic environment.     

Rapid and accurate species and genomic species identification and exhaustive population diversity assessment of Agrobacterium spp. using recA-based PCR

Agrobacteria are common soil bacteria that interact with plants as commensals, plant growth promoting rhizobacteria or alternatively as pathogens. Indigenous agrobacterial populations are composites, generally with several species and/or genomic species and several strains per species. We thus developed a recA-based PCR approach to accurately identify and specifically detect agrobacteria at various taxonomic levels. Specific primers were designed for all species and/or genomic species of Agrobacterium presently known, including 11 genomic species of the Agrobacterium tumefaciens complex (G1-G9, G13 and G14, among which only G2, G4, G8 and G14 still received a Latin epithet: pusense, radiobacter, fabrum and nepotum, respectively), A. larrymoorei, A. rubi, R. skierniewicense, A. sp. 1650, and A. vitis, and for the close relative Allorhizobium undicola. Specific primers were also designed for superior taxa, Agrobacterium spp. and Rhizobiaceace. Primer specificities were assessed with target and non-target pure culture DNAs as well as with DNAs extracted from composite agrobacterial communities. In addition, we showed that the amplicon cloning-sequencing approach used with Agrobacterium-specific or Rhizobiaceae-specific primers is a way to assess the agrobacterial diversity of an indigenous agrobacterial population. Hence, the agrobacterium-specific primers designed in the present study enabled the first accurate and rapid identification of all species and/or genomic species of Agrobacterium, as well as their direct detection in environmental samples.     

Two new species of Grindelia (Astereae,Asteraceae) from Uruguay

Taxonomic revision of South American species ofGrindelia Willd. has revealed two new species from Uruguay:G. rupestris, an erect subshurb with crowded obovate denticulate leaves, subsessile heads, and pappus composed of numerous awns, andG. linearifolia, a prostrate shrublet with small entire linear leaves. Both species are described and illustrated. A key for the UruguayanGrindelia species is provided.     

Evidence for Cryptic Speciation in Directly Transmitted Gyrodactylid Parasites of Trinidadian Guppies

Cryptic species complexes are common among parasites, which tend to have large populations and are subject to rapid evolution. Such complexes may arise through host-parasite co-evolution and/or host switching. For parasites that reproduce directly on their host, there might be increased opportunities for sympatric speciation, either by exploiting different hosts or different micro-habitats within the same host. The genus Gyrodactylus is a specious group of viviparous monogeneans. These ectoparasites transfer between teleosts during social contact and cause significant host mortality. Their impact on the guppy (Poecilia reticulata), an iconic evolutionary and ecological model species, is well established and yet the population genetics and phylogenetics of these parasites remains understudied. Using mtDNA sequencing of the host and its parasites, we provide evidence of cryptic speciation in Gyrodactylus bullatarudis, G. poeciliae and G. turnbulli. For the COII gene, genetic divergence of lineages within each parasite species ranged between 5.7 and 17.2%, which is typical of the divergence observed between described species in this genus. Different lineages of G. turnbulli and G. poeciliae appear geographically isolated, which could imply allopatric speciation. In addition, for G. poeciliae, co-evolution with a different host species cannot be discarded due to its host range. This parasite was originally described on P. caucana, but for the first time here it is also recorded on the guppy. The two cryptic lineages of G. bullatarudis showed considerable geographic overlap. G. bullatarudis has a known wide host range and it can also utilize a killifish (Anablepsoides hartii) as a temporary host. This killifish is capable of migrating overland and it could act as a transmission vector between otherwise isolated populations. Additional genetic markers are needed to confirm the presence of these cryptic Gyrodactylus species complexes, potentially leading to more in-depth genetic, ecological and evolutionary analyses on this multi-host-parasite system.     

On the taxonomic status of some Glyptodontidae (Mammalia,Xenarthra, Cingulata) from the Pleistocene of South America

The anatomical and taxonomic knowledge of some groups of Glyptodontidae (Mammalia, Cingulata) is still very poor. In addition, a strict typological/morphological taxonomic criterion was used in recognizing many taxa, especially during the second half of the 19th century and the first of the 20th century. This particular situation resulted in a clear overestimation diversity, mainly with respect to the South American glyptodonts. In this scenario, this paper analyzes the taxonomic status of some Glyptodontinae through a precise comparative study with well characterized taxa. The main results show that the genera Pseudothoracophorus Castellanos (P. depressus) and Chlamydotherium Lund, one species of the genus “Boreostracon” Simpson (B. corondanus), and one species of the genus Glyptodon Owen (G. falkneri), actually represents juvenile specimens referable to Glyptodon Owen; the genus Neothoracophorus Ameghino (N. elevatus) could be related either to Glyptodon Owen or Glyptotherium Osborn. Another species, Heteroglyptodon genuarioi, presents an almost identical morphology compared with the recognized species of Glyptodon (e.g. G. munizi and G. reticulatus). In this sense, the diagnostic characters described for Glyptodon perforatus Ameghino, a taxon with biostratigraphic relevance since it is characteristic of the Lujanian Age/Stage (late Pleistocene-early Holocene), are also present in other species of Glyptodon, especially G. reticulatus and G. clavipes, very frequent taxa in southern South America.     

Fusarium Species from Nepalese Rice and Production of Mycotoxins and Gibberellic Acid by Selected Species

Infection of cereal grains with Fusarium species can cause contamination with mycotoxins that affect human and animal health. To determine the potential for mycotoxin contamination, we isolated Fusarium species from samples of rice seeds that were collected in 1997 on farms in the foothills of the Nepal Himalaya. The predominant Fusarium species in surface-disinfested seeds with husks were species of the Gibberella fujikuroi complex, including G. fujikuroi mating population A (anamorph, Fusarium verticillioides), G. fujikuroi mating population C (anamorph, Fusarium fujikuroi), and G. fujikuroi mating population D (anamorph, Fusarium proliferatum). The widespread occurrence of mating population D suggests that its role in the complex symptoms of bakanae disease of rice may be significant. Other common species were Gibberella zeae (anamorph, Fusarium graminearum) and Fusarium semitectum, with Fusarium acuminatum, Fusarium anguioides, Fusarium avenaceum, Fusarium chlamydosporum, Fusarium equiseti, and Fusarium oxysporum occasionally present. Strains of mating population C produced beauvericin, moniliformin, and gibberellic acid, but little or no fumonisin, whereas strains of mating population D produced beauvericin, fumonisin, and, usually, moniliformin, but no gibberellic acid. Some strains of G. zeae produced the 8-ketotrichothecene nivalenol, whereas others produced deoxynivalenol. Despite the occurrence of fumonisin-producing strains of mating population D, and of 8-ketotrichothecene-producing strains of G. zeae, Nepalese rice showed no detectable contamination with these mycotoxins. Effective traditional practices for grain drying and storage may prevent contamination of Nepalese rice with Fusarium mycotoxins.     

Low levels of genetic variation within populations of the four rare orchids Gymnadenia cucullata, Gymnadenia camtschatica, Amitostigma gracile, and Pogonia minor in South Korea: indication of genetic drift and implications for conservation

Many terrestrial orchids are relatively rare, and their populations are small and spatially isolated. Population genetics theory predicts that populations of such species, affected historically by random genetic drift, would maintain low levels of genetic diversity and exhibit a high degree of among-population divergence. To test this prediction, I used enzyme electrophoresis. Genetic diversity within populations of the four rare, terrestrial orchids Gymnadenia cucullata (four populations) and its congener G. camtschatica (four populations), Amitostigma gracile (four populations in one region and three in another region), and Pogonia minor (three populations each in two regions) was investigated in South Korea at the landscape level. As predicted, populations of the four species harbor low levels of genetic diversity within populations: the mean percentage of polymorphic loci, %P, the mean number of alleles per locus, A, and the average expected heterozygosity, H _e, were 12.5%, 1.13, and 0.036 for G. cucullata, respectively; 18.2%, 1.18, and 0.067 for G. camtschatica; 3.0%, 1.04, and 0.009 for A. gracile; and 2.7%, 1.06, and 0.014 for P. minor. Except for G. camtschatica (F _ST = 0.000), a significantly high degree of genetic divergence between conspecific populations was detected in the other three species: F _ST = 0.081 for G. cucullata; 0.348 and 0.811 in two regions for A. gracile; and 0.469 and 0.758 in two regions for P. minor. In addition, individuals within populations are highly structured in the four species (overall F _IS = 0.276 for G. cucullata; 0.308 for G. camtschatica; 0.758 for A. gracile; and 0.469 for P. minor), suggesting that selfing, biparental inbreeding, and/or consanguineous mating have occurred in populations of the four species. With the exception of G. camtschatica, an allele at a locus is fixed in a population, whereas alternative alleles with low or high frequencies are detected in another population across the landscape. My results suggest that evolutionary histories of G. cucullata, A. gracile, and P. minor are different from G. camtschatica. Historical genetic drift would be an important force shaping the genetic structure of the Korean populations of G. cucullata, A. gracile, and P. minor. For G. camtschatica on Ulleung Island, relatively higher levels of genetic variation within populations compared to its congener G. cucullata (H _e = 0.067 vs. 0.036) and little evidence of population genetic structure among populations (F _ST = 0.000) suggest that individuals were, presumably, once continuously distributed on Ulleung Island, and populations have recently been isolated by habitat fragmentation through natural succession (e.g,. probably the encroachment of woody vegetation on grasslands) or human-mediated disturbances (e.g., collections). Thus, conservation strategies for the four species should be differently developed in order to preserve genetic diversity in South Korea.     

Acacipetalin in Acacia constricta from north America

Acacipetalin, previously known only from the African legumes Acacia sieberiana var. woodii and Acacia hebeclada, has been isolated from an American species of the genus, Acacia constricta.     

Taxonomic significance of pollen morphology for species delimitation in <Emphasis Type="Italic">Psidium</Emphasis> (Myrtaceae)

Previous studies reported Psidium as one of the most difficult genera to delimit within the American Myrtaceae. Even though palynology has improved the taxonomy of Angiosperms, information about the usefulness of pollen morphology for taxonomic purposes in Myrtaceae remains contradictory. Here, we investigate the significance of pollen morphology for Psidium taxonomy with specific focus on its usefulness for determining species groups of taxonomic significance. Pollen traits observed by light and scanning electron microscopy were quantified and examined using cluster and ordination analyses. Average size of pollen grains was visualized by boxplots. Pollen grains of Psidium are isopolar, oblate, peroblate or oblate-spheroidal, 3-syncolporate or 4-syncolporate. The sexine ornamentation is rugulate, granulate or spinulose-granulate and differs between the mesocolpium and apocolpium. Cluster analysis revealed four distinct groups: Psidium cauliflorum (G1) and Psidium oligospermum (G3) as single-species groups; Psidium brownianum, P. oblongatum, P. ovale, P. sartorianum, P. guajava, Psidium sp. 1, Psidium sp. 2 (G2), and Psidium cattleianum, P. longipetiolatum, P. guineense, P. myrtoides (G4). Supported by ordination analysis, three traits better explained these groups: type of exine ornamentation, size of P-EV and pollen shape. The used approach efficiently distinguished related species, as well as explained species groups of taxonomic significance suggesting pollen morphology to be a significant source of information for taxonomic studies in Psidium.     

Infrageneric variation in partner specificity: multiple ectomycorrhizal symbionts associate with Gnetum gnemon (Gnetophyta) in Papua New Guinea

Majority of autotrophic plants and fungi associate with multiple mycorrhizal partners, with notable exceptions being Gnetum africanum, Pisonia grandis, and Alnus spp from the phytobiont perspective. We hypothesized that an understorey tree species Gnetum gnemon hosts a narrow range of mycobionts as shown in G. africanum and suggested for South American species. Sampling and molecular analysis of G. gnemon root tips revealed that besides Scleroderma spp. this gymnosperm tree associates with several fungal species from unrelated lineages. However, all Scleroderma isolates that associate with Gnetum spp. belong to a narrow clade close to Scleroderma sinnamariense. Our results demonstrate for the first time that specificity for mycobionts may substantially differ within an ectomycorrhizal plant genus.     

Molecular cytogenetic studies of the “Xanthocephalum group” (Asteraceae)

Fourteen North American members of the “Xanthocephalum group” were studied by classical and molecular cytogenetics. Location and number of rDNA sites were determined by FISH. For the 5S rDNA, a probe was obtained from Prionopsis ciliata. Most species were diploid (2n?=?12), although Isocoma menziesii, Grindelia hirsutula, G. robusta, both varieties of G. stricta, and one population of G. camporum were tetraploid (2n?=?24). Diploid Grindelia and Prionopsis ciliata were 5m?+?1sm, tetraploids 10m?+?2sm, except G. hirsutula (8m?+?4sm), and Isocoma and Olivaea 6m?+?2sm and 3m?+?3sm, respectively. Most species had satellites on the short arms of m pairs: two in tetraploids and P. ciliata and one in diploids. Satellites were associated with two CMA⁺/DAPI^? bands in diploid species and four bands in tetraploids and in P. ciliata. rDNA loci (two in diploids to four in tetraploids) may be indicative of ploidy level. Grindelia tetraploids could have originated recently by autopolyploidy. Chromosome duplication was followed by modifications in the genome structure, resulting in higher heterochromatin amounts not associated with NORs. There is only one 5S site per basic genome in para or pericentromeric regions. Although not always large, chromosome variation has accompanied the evolutionary divergence of the taxa studied.     

Sesquiterpenoid aldehyde quinones and derivatives in pigment glands of Gossypium

The resistance of Gossypium species to insects is enhanced by compounds in their lysigenous pigment glands. In cultivated cottons, glands in achlorophyllous plant parts contained predominately the terpenoid aldehyde gossypol in G. hirsutum, and gossypol and its methyl and dimethyl ethers in G. barbadense. Glands in young green tissues, however, contained hemigossypolone as the predominant terpenoid aldehyde in G. hirsutum, and a new quinone, hemigossypolone-7-methyl ether, in G. barbadense. As glands aged in green tissues, the sesquiterpenoid quinones were replaced by several C₂₅-terpenoids formed by the Diels-Alder reaction of the quinones with myrcene or trans-β-ocimene. Two C₂₅-terpenoids isolated from G. barbadense, but not G. hirsutum, were the methyl ethers of heliocides H₁ and H₄ and were designated heliocides B₁ and B₄, respectively. A dark red pigment, gossyrubilone, from glands of young leaves of both species is the isopentylimine of hemigossypolone. Similar red imines, formed from sesquiterpenoid quinones and amino acids, resembled the red coloration of the envelope cells surrounding the gland sac. The terpenoid quinones of Gossypium had physical characteristics different from quinones in Bombax which apparently were incorrectly identified as being the same. A survey of the terpenoid quinones and their heliocide derivates in wild Gossypium species and related genera in the Gossypieae showed considerable diversity which may be used for establishing biochemical and phylogenetic relationships.     

Analysis of bacterial communities associated with spores of Gigaspora margarita and Gigaspora rosea

The spores of arbuscular mycorrhizal fungi (AMF) form a unique microhabitat that is suitable for the colonization by many species of bacteria. The aim of the current study was to analyze the bacterial communities associated with the surface of spores of the AMF species Gigaspora margarita MAFF 520054 and Gigaspora rosea JP1. The two AMF species were propagated with tobacco (Nicotiana tabacum) grown in a mixture of sand and soil. In another experiment, G. margarita was propagated with tobacco or alfalfa (Medicago sativa) grown in vermiculite or a mixture of sand and soil. The bacterial community composition of the new-formed spores and sand/soil substrate was analyzed using PCR of 16S rDNA fragments and denaturing gradient gel electrophoresis (DGGE). Clustering analysis revealed that the bacterial communities on the surface of G. margarita spores was different form that in the substrate or on the surface of the G. rosea spores, and both the host plant and the substrate could influence the composition of spore-associated bacterial populations of the G. margarita. Sequence analysis of the major DGGE bands of G. margarita spore samples revealed that most of the bacterial sequences were affiliated with the phyla Proteobacteria (Azospirillum, Azovibrio, Polyangium, Ramlibacter, Rubrivivax, Sphingomonas, and Rhizobium) and Actinobacteria (Streptomyces, Amycolatopsis, and Pseudonocardia).     

Gambierdiscus balechii sp. nov (Dinophyceae), a new benthic toxic dinoflagellate from the Celebes Sea (SW Pacific Ocean)

A new benthic toxic dinoflagellate is described from the Celebes Sea. Gambierdiscus balechii sp. nov. was isolated from seaweeds growing in tidal ponds. Its morphology was studied by means of LM and SEM; G. balechii has a very ornamented theca, a hatchet shaped second apical plate, a narrow second antapical plate and an asymmetrical third precigular plate, a unique combination of characters among Gambierdiscus species. It has a very wide size range with widths from 36 to 88 μm. Phylogenetic analyses of two G. balechii strains, based on LSU rRNA (D8–D10) and partial SSUrRNA sequences confirmed that these clustererd in its’ own group, separated from the rest of Gambierdiscus species and with G. pacificus, G. belizeanus and G. scabrosus as its closest relatives. Thecate cysts are described from culture as non motile vegetative-like cells which germinated after being isolated and transferred to fresh medium. Mouse tests showed that this species is toxic and hence it is a potential cause of ciguatera in the Celebes Sea.     

Description of five novel thermophilic species of the genus Thermus: Thermus hydrothermalis sp. nov., Thermus neutrinimicus sp. nov., Thermus thalpophilus sp. nov., Thermus albus sp. nov., and Thermus altitudinis sp. nov., isolated from hot spring sediments

Biological denitrification is a significant process in nitrogen biogeochemical cycle of terrestrial geothermal environments, and Thermus species have been shown to be crucial heterotrophic denitrifier in hydrothermal system. Five Gram-stain negative, aerobic and rod-shaped thermophilic bacterial strains were isolated from hot spring sediments in Tibet, China. Phylogenetic analysis based on 16S rRNA gene and whole genome sequences indicated that these isolates should be assigned to the genus Thermus and were most closely related to Thermus caldifontis YIM 73026^T, and Thermus brockianus YS38^T. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the five strains and the type strains of the genus Thermus were lower than the threshold values (95% and 70%, respectively) recommended for bacterial species, which clearly distinguished the five isolates from other species of the genus Thermus and indicated that they represent independent species. Colonies are circular, convex, non-transparent. Cell growth occurred at 37–80 °C (optimum, 60–65 °C), pH 6.0–8.0 (optimum, pH 7.0) and with 0–2.0% (w/v) NaCl (optimum, 0–0.5%). Denitrification genes (narG, nirK, nirS, and norB genes) detected in their genomes indicated their potential function in nitrogen metabolism. The obtained results combined with those of morphological, physiological, and chemotaxonomic characteristics, including the menaquinones, polar lipids, and cellular fatty acids showed that the isolates are proposed as representing five novel species of the genus Thermus, which are proposed as Thermus hydrothermalis sp. nov. SYSU G00291^T, Thermus neutrinimicus sp. nov. SYSU G00388^T, Thermus thalpophilus sp. nov. SYSU G00506^T, Thermus albus sp. nov. SYSU G00608^T, Thermus altitudinis sp. nov. SYSU G00630^T.     

Reproductive biology of mixed-species populations of Goodyera (orchidaceae) in northern Michigan

The reproductive biology ofGoodyera oblongifolia, G. repens var.ophioides andG. tesselata is discussed with emphasis on the reproductive isolating mechanisms operating in mixed-species populations. Cytology, phenology and pollination of the above three species were studied. Artificial hybridizations were made of these three species and ofG. pubescens. Results show that within mixed-species populations,G. oblongifolia,G. repens var.ophioides andG. tesselata are not completely isolated reproductively, and hybridization does occur. The deleterious effects of the loss of gametes to interspecific crosses are reduced by seasonal isolation, perennial growth and geitonogamous seed production which is encouraged by self-compatibility and clonal growth. Thus, hybridization in mixed-species populations is apparently kept to levels low enough to allow the species to maintain their identities.     

A chemosystematic investigation on Ipomopsis

The diminutive North American desert annual species of Ipomopsis, Section Microgilia, I. depressa and I. polycladon, agree with other members of the genus in having a flavonoid syndrome based upon 6-methoxyflavonols. Patuletin is the predominant aglycone present but traces of eupatolitin and eupalitin were detected. In I. polycladon, four glycosides of patuletin and one of eupalitin were isolated and identified.     

PCR-Denaturing Gradient Gel Electrophoresis Profiling of Inter- and Intraspecies 18S rRNA Gene Sequence Heterogeneity Is an Accurate and Sensitive Method To Assess Species Diversity of Arbuscular Mycorrhizal Fungi of the Genus Gigaspora

Despite the importance of arbuscular mycorrhizal fungi in the majority of terrestrial ecosystems, their ecology, genetics, and evolution are poorly understood, partly due to difficulties associated with detecting and identifying species. We explored the inter- and intraspecies variations of the 18S rRNA genes of the genus Gigaspora to assess the use of this marker for the discrimination of Gigaspora isolates and of Gigasporaceae populations from environmental samples. Screening of 48 Gigaspora isolates by PCR-denaturing gradient gel electrophoresis (DGGE) revealed that the V3-V4 region of the 18S rRNA gene contained insufficient variation to discriminate between different Gigaspora species. In contrast, the patterns of 18S ribosomal DNA (rDNA) heterogeneity within the V9 region of this marker could be used for reliable identification of all recognized species within this genus. PCR-DGGE patterns provided insight into some putative misidentifications and could be used to differentiate geographic isolates of G. albida, G. gigantea, and G. margarita but not G. rosea. Two major clusters were apparent based upon PCR-DGGE ribotype patterns, one containing G. albida, G. candida, G. ramisporophora, and G. rosea and the other containing G. decipiens and G. margarita. Dissection of the DGGE patterns by cloning, DGGE screening, and sequencing confirmed these groupings and revealed that some ribotypes were shared across species boundaries. Of the 48 isolates examined, only two displayed any spore-to-spore variation, and these exceptions may be indicative of coisolation of more than one species or subspecies within these cultures. Two Brazilian agricultural soils were also analyzed with a Gigasporaceae-specific nested PCR approach, revealing a dominance of G. margarita within this family.