Parvodontia relampaga sp. nov.: A Cystostereaceae fungal pathogen that is the causal agent of relampago blight of woody plants in Florida, USA.

Starting in the fall of 2019, mortality, blight symptoms, and signs of white fungal mycelia were observed on external host tissues of non-native landscape trees as well as numerous native trees, understory shrubs, and vines throughout northern and central Florida, USA. We determined that the fungus is an undescribed species of Basidiomycota based on morphological characteristics and DNA sequence analysis. Phylogenetic analyses of the internal transcribed spacer (ITS), large subunit (LSU), and translation elongation factor 1-alpha (tef1) regions revealed that this novel plant pathogen is an undescribed taxon of the genus Parvodontia (Cystostereaceae, Agaricales). We propose the name Parvodontia relampaga sp. nov. which describes its unique morphological features and phylogenetic placement. We confirmed the pathogenicity of P. relampaga in greenhouse inoculations on host plants from which strains of this novel pathogen were isolated, including the non-native gymnosperm Afrocarpus falcatus, the non-native and commercially important Ligustrum japonicum, and the native tree Quercus hemisphaerica. P. relampaga was also detected on a total of 27 different species of woody host plants, including such economically and ecologically important hosts as Fraxinus, Ilex, Magnolia, Persea, Prunus, Salix, Vitis, and Vaccinium. For this new plant disease, we propose the name "relampago blight," which refers to the lightning-like rhizomorph growth (relámpago means 'lightning' in Spanish). This study presents a newly discovered fungal taxon with a wide host range on both angiosperms and gymnosperms that may be an emerging pathogen of concern in Florida and the Gulf Coast region.

Revising the taxonomic placement of Laetiporus persicinus within the Laetiporaceae.

The fungus currently known as Laetiporus persicinus is a recognizable brown-rot decayer that is widespread on oak hosts in the southeastern United States. This species was first described as Polyporus persicinus in 1872 based on collections by Henry W. Ravenel from South Carolina. In this study, we elucidate the phylogenetic relationships of Laetiporus persicinus based on maximum likelihood and Bayesian inference analyses of a four-locus data set (18S, 28S, rpb2, and tef1) from taxa within the Fomitopsidaceae and Laetiporaceae. The internal transcribed spacer (ITS) region was analyzed separately because it was not possible to align this locus across a diverse data set that included taxa from multiple families. Our analysis and previous studies indicate that Laetiporus persicinus does not belong to Laetiporus sensu stricto, and we found a strongly supported relationship between Laetiporus persicinus and the African species Kusaghiporia usambarensis, despite the fact that the 28S phylogeny resolved a different (but unsupported) topology. Here, we propose Kusaghiporia persicinus, comb. nov., based on a combination of morphological and molecular data. Laetiporus persicinus shares many morphological features with K. usambarensis that are missing in other Laetiporus species, including centrally stipitate basidiomata, a brown to pinkish pileus surface, and a pore layer that bruises when touched. However, K. usambarensis and L. persicinus differ in basidiospore size and shape as well as their geographic distributions. We provide a revised taxonomic treatment for this common wood-decay fungus.