Abstracts Biological Sciences

Molecular ecology of Boletinellus merulioides and systematics of the Boletineae

by Mitchell E Nuhn

This work focuses on members of the Boletales. This order is comprised of a morphological and ecologically diverse set of species. While the vast majority of species are pileate-stipitate with pores and have a mutualistic nutritional strategy ectomycorrhal (ECM), there are resupinate and gilled species, and saprotrophs and mycoparasites as well. In the first chapter, we review the ecological niche occupied by <i>Boletinellus merulioides. </i> This species was originally considered to be ECM, the symbiont to <i> Fraxinus americana.</i> This hypothesis was rejected, and replaced by the possibility of a mutualism with an <i>F. americana</i> aphid pest, <i>Prociphilus fraxinifolii.</i> We present the first study that observed all three species, since the original publication, the first molecular data for each species, and isotopic fractionation results for <i> B. merulioides</i> and <i>P. fraxinifolii.</i> Additionally, we describe a new morphology for sclerotia of <i>B. merulioides.</i> In total, we are unable to reject the possibility of a facultative mutualism between <i>B. merulioides</i> and <i>P. fraxinifolii.</i> Chapters two through five review systematics in the <i>Boletineae. </i> Chapter two presents the most comprehensive phylogenetic review of the <i>Boletineae,</i> at the time publication, and remains one of the most inclusive <i>Boletineae phylogenies.</i> Three genes, nuclear large subunit, translation elongation factor 1-alpha, and DNA directed RNA polymerase II largest subunit, were used. This chapter is a summary of <i> Boletineae</i> taxonomy and morphological characteristics, with a clade by clade analysis. We present compelling evidence for the mycoparasitic nutritional mode of <i>Buchwaldoboletus lignicola.</i> Additionally, we found that <i>Chalciporus piperatus,</i> a close relative of <i> B. lignicola</i>, is likely to be a mycoparasite. We present strong evidence that the genus <i>Boletus</i> is limited to single clade that contains approximately 10% of the validly published <i>Boletus</i> species. A subset of the taxa sampled in chapter two was used in the phylogenies presented in chapters three, four, and five. Each of these chapters reviews the phylogenetic placement of traditionally problematic species/genera; <i> Surotius eximius, Harrya chromapes</i> and allies, and the Boletaceae species with longitudinally striated spores. These groups have been in multiple. Our results show that <i>Sutorius</i> and <i>Harrya</i> species are distinct from other Boletacaea species and that the longitudinally striated species have been lumped together. By correcting taxonomic confusion and using a multigene data set we are able to resolve these problematic species, and provide a path for future systematics and evolutionary analysis.