Geosmithia spp. (Ascomycota: Hypocreales) are little-studied, dry-spored fungi that occur in galleries built by many phloeophagous bark beetles. This study mapped the distribution and environmental preferences of Geosmithia species occurring in galleries of temperate European bark beetles. One hundred seven host tree samples of 16 tree species infested with 23 subcortical insect species were collected from across Europe during the years 1997-2005. Over 600 Geosmithia isolates from the beetles were sorted into 17 operational taxonomic units (OTUs) based on their phenotype similarity and phylogeny of internal transcribed spacer (ITS) region of rDNA (ITS1-5.8S-ITS2). The OTUs represent six known species and eight undescribed taxa. Ninety-two samples infested with subcortical insects were characterized by the presence/absence of OTUs and the similarity among the samples was evaluated. Geographically distant populations of the same beetle species host relatively uniform Geosmithia communities across large geographic areas (ranging from southern Bulgaria to the Czech Republic). This suggests effective dispersal of Geosmithia spp. by bark beetles. Clustering of similar samples in ordination analysis is correlated predominantly with the isolation source (bark beetles and their respective feeding plant), but not with their geographical origin. The composition of the Geosmithia OTU community of each bark beetle species depends on the degree of isolation of the species' niches. Thus, Geosmithia communities associated with regularly co-occurring bark beetle species are highly similar. The similarity decreases with decreasing frequency of beetle species' co-occurrence, a pattern resembling that of entomochoric ophiostomatoid fungi. These findings suggest that: 1) communities of Geosmithia spp. are vector-specific; 2) at least in some cases, the association between Geosmithia OTUs and bark beetles may have been very stable and symbioses are likely to be a fundamental factor in the speciation of Geosmithia fungi; and 3) that even nonsticky spores of Geosmithia are suitable for maintaining an insect-fungus association, contrary to previous hypotheses.

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We studied genetic variability of 100 isolates of Claviceps purpurea by using randomly amplified polymorphic DNA (RAPD), an EcoRI restriction site polymorphism in the 5.8S ribosomal DNA (rDNA), the alkaloids produced, and conidial morphology. We identified three groups: (i) group G1 from fields and open meadows (57 isolates), (ii) group G2 from shady or wet habitats (41 isolates), and (iii) group G3 from Spartina anglica from salt marshes (2 isolates). The sclerotia of G1 isolates contained ergotamines and ergotoxines; G2 isolates produced ergosine and ergocristine along with small amounts of ergocryptine; and G3 isolates produced ergocristine and ergocryptine. The conidia of G1 isolates were 5 to 8 m long, the conidia of G2 isolates were 7 to 10 m long, and the conidia of G3 isolates were 10 to 12 m long. Sclerotia of the G2 and G3 isolates floated on water. In the 5.8S rDNA analysis, an EcoRI site was found in G1 and G3 isolates but not in G2 isolates. The host preferences of the groups were not absolute, and there were host genera that were common to both G1 and G2; the presence of members of different groups in the same locality was rare. Without the use of RAPD or rDNA polymorphism, it was not possible to distinguish the three groups solely on the basis of phenotype, host, or habitat. In general, populations of C. purpurea are not host specialized, as previously assumed, but they are habitat specialized, and collecting strategies and toxin risk assessments should be changed to reflect this paradigm shift.Claviceps purpurea is an ergot fungus with a wide host range that includes the entire subfamily Pooideae, many members of the Arundinoideae, and some species belonging to the chloridoid and panicoid groups (4, 15). Its distribution is basically Holarctic, but it has been recorded in Arctic regions (14) and also occurs in southern temperate and subtropical regions. Due to movement with cereal and grass seeds by migrants, the center of origin of this species is not known.C. purpurea is morphologically quite variable. Sclerotial length ranges from 2 to 50 mm, and the color of the stromata varies over a wide range of red shades from wine to purple (25) and even to orange (31). Conidial size and shape also are polymorphic; the conidia range from oval spores that are 5 m long to cylindric or elongated spores that are up to 13 m long (15,25,31). The sclerotia contain peptide alkaloids that belong to three basic groups, the ergotamines (with alanine as the first amino acid entering the cyclopeptide moiety), the ergotoxines (with valine), and the rarely found ergoxines (with 2-aminoisobutyric acid) (for reviews see references 7 and 33).For the last 100 years, researchers have tried to use this variation to establish varieties, special forms, or races (1), and the primary focus has been on detection of host-specific groups. Stäger introduced four special forms: secalis, lolii (later joined with secalis) (2), milii (on Milium and Brachypodium only), and glyceriae (suspected to be Claviceps wilsonii) for C. purpurea se...