Fungal mitospores may function as dispersal units and/ or spermatia and thus play a role in distribution and/or mating of species that produce them. Mitospore production in ectomycorrhizal (EcM) Pezizales is rarely reported, but here we document mitospore production by a high diversity of EcM Pezizales on three continents, in both hemispheres. We sequenced the internal transcribed spacer (ITS) and partial large subunit (LSU) nuclear rDNA from 292 spore mats (visible mitospore clumps) collected in Argentina, Chile, China, Mexico and the USA between 2009 and 2012. We collated spore mat ITS sequences with 105 fruit body and 47 EcM root sequences to generate operational taxonomic units (OTUs). Phylogenetic inferences were made through analyses of both molecular data sets. A total of 48 OTUs from spore mats represented six independent EcM Pezizales lineages and included truffles and cup fungi. Three clades of seven OTUs have no known meiospore stage. Mitospores failed to germinate on sterile media, or form ectomycorrhizas on Quercus, Pinus and Populus seedlings, consistent with a hypothesized role of spermatia. The broad geographic range, high frequency and phylogenetic diversity of spore mats produced by EcM Pezizales suggests that a mitospore stage is important for many species in this group in terms of mating, reproduction and/or dispersal.

The two species of Mirids, Sahlbergella singularisHagl. and Distantiella theobroma (Dist.), are important pests of cacao (Theobroma cacao L.) in the Gold Coast. The damage sustained by the cacao is due, in part, to the direct effects of feeding by these insects, but more to the subsequent invasion of the resulting lesions by the weakly pathogenic fungus, Calonectria rigidiuscula (Berk. & Br.) Sacc.In the field, Mirid damage may be classified into three categories. “Blast” is the result of light diffuse attack and is so named because of its similarity to fire damage. “Stagheaded cacao” is more severe, the trees showing numeroussmall crown branches but forming a poor canopy. “Mirid pocket” describes severe damage, normally limited to a small area, the trees losing the crown completely and the polelike trunks bearing numerous lateral chupons. In general, stagheaded symptoms are more prevalent where cacao is grown without shade, and pockets where cultivation of cacao utilises shade trees.Consideration of the factors associated with Mirid damage shows that it is correlated with breaks in the cacao canopy. Evidence is brought forward to suggest that such breaks normally precede, rather than result from, Mirid attack. The canopy itself is unsuitable for the development of either species, the major part of the population being confined to the sub-canopy levels. The initial causes of the breaks are, most frequently, the die-backs associated with swollen shoot or with adverse water relations. The falling of shade trees causes a number of breaks, and, where cacao is grown without shade, the Mirids themselves may be a cause.The most important single factor influencing the form of the cacao canopy, and thus the course of Mirid attack, is the amount of overhead shade, particularly that provided by trees little taller than the cacao itself. Shade which is too dense causes etiolation of the cacao and thus renders it susceptible to attack, the resulting damage generally taking the form of a pocket. Shade which is too sparse does not shield the cacao from the adverse effects of exposure. The Mirid damage in such areas generally assumes the stagheaded form.It is suggested, from field experiments, that the invasion by Mirids of areas suitable for colonisation is not by random movements, but is determined by the change in some physical factor resulting from the broken canopy. Changes in light intensity are the most obvious results of such breaks, but further experiments are needed to determine which is the operating factor.Degraded cacao is prevented from recovery, not by Mirid attack alone, but by the interaction of it with the presence of C. rigidiuscula, and by increased exposure.The sampling methods employed are described, and the bearing of the results upon control measures is discussed.

Temperate ectomycorrhizal (ECM) fungi show segregation whereby some species dominate in organic layers and others favor mineral soils. Weak layering in tropical soils is hypothesized to decrease niche space and therefore reduce the diversity of ectomycorrhizal fungi. The Neotropical ECM tree Dicymbe corymbosa forms monodominant stands and has a distinct physiognomy with vertical crown development, adventitious roots and massive root mounds, leading to multi-stemmed trees with spatially segregated rooting environments: aerial litter caches, aerial decayed wood, organic root mounds and mineral soil. We hypothesized that these microhabitats host distinct fungal assemblages and therefore promote diversity. To test our hypothesis, we sampled D. corymbosa ectomycorrhizal root tips from the four microhabitats and analyzed community composition based on pyrosequencing of fungal internal transcribed spacer (ITS) barcode markers. Several dominant fungi were ubiquitous but analyses nonetheless suggested that communities in mineral soil samples were statistically distinct from communities in organic microhabitats. These data indicate that distinctive rooting zones of D. corymbosa contribute to spatial segregation of the fungal community and likely enhance fungal diversity.

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