Families and genera of diaporthalean fungi associated with canker and dieback of tree hosts

Abstract

In this study we accept 25 families in <i>Diaporthales</i> based on phylogenetic analyses using partial ITS, LSU, <i>rpb2</i> and <i>tef1-α</i> gene sequences. Four different families associated with canker and dieback of tree hosts are morphologically treated and phylogenetically compared. These include three new families (<i>Diaporthostomataceae</i>, <i>Pseudomelanconidaceae</i>, <i>Synnemasporellaceae</i>), and one new genus, <i>Dendrostoma</i> (<i>Erythrogloeaceae</i>). <i>Dendrostoma</i> is newly described from <i>Malus spectabilis</i>, <i>Osmanthus</i> <i>fragrans</i> and <i>Quercus</i> <i>acutissima</i> having fusoid to cylindrical, bicellular ascospores, with three new species namely <i>D. mali</i>, <i>D. osmanthi</i> and <i>D. quercinum</i>. <i>Diaporthostomataceae</i> is characterised by conical and discrete perithecia with bicellular, fusoid ascospores on branches of <i>Machilus leptophylla</i>. <i>Pseudomelanconidaceae</i> is defined by conidiogenous cells with apical collarets and discreet annellations, and the inconspicuous hyaline conidial sheath when mature on <i>Carya cathayensis</i>, compared to morphologically similar families <i>Melanconidaceae</i> and <i>Juglanconidaceae</i>. <i>Synnemasporellaceae</i> is proposed to accommodate fungi with synnematous conidiomata, with descriptions of <i>S. toxicodendri</i> on <i>Toxicodendron sylvestre</i> and <i>S. aculeans</i> on <i>Rhus copallina</i>.