Morphological and molecular characterization of Rhytisma filamentosum sp. nov. from Nagano Prefecture, Japan

Abstract

We describe a new fungal species, Rhytisma filamentosum, which causes tar spot disease on Salix integra in Nagano Prefecture, Japan. Its most distinctive morphological features are asci and ascospores that are distinctly longer than those of other Rhytisma species on Salix. rDNA ITS and LSU sequence analyses also indicate that this fungus is sufficiently distinct from other Rhytisma species to justify new species status.

First report of Rhytisma filamentosum causing tar‐spot disease on Salix koriyanagi

“…Morphological characteristics of our samples were consistent with the descriptions of R. filamentosum (Masumoto et al, ). Ascostromata on fallen leaves were amphigenous, black, not shiny, roughly circular, and 2–5 mm in diameter (Figure a,b).…”

“…Rhytisma filamentosum was recently reported as a new species found only on S. integra in Japan (Masumoto et al, ). Interestingly, S. koriyanagi , which is a newly identified host in Korea, is phylogenetically close to S. integra (Kim, Kim, & Park, ; Newsholme, ).…”

“…Lophodermium pinastri (GenBank Accession No. and ) was used as an outgroup taxon according to the previous phylogenetic results of Masumoto, Tojo, Uchida, and Imura (). Concatenated sequences of the ITS and LSU regions of the rDNA were generated for each of the species and aligned using MEGA5 software (Tamura et al, ).…”

Lophodermium resinosum sp. nov. from red pine (Pinus resinosa) in Eastern Canada

“…The detection of a novel Lophodermium species on an endemic North American host with a poorly characterized microbiota is expected given the recent descriptions of novel Lophodermium and D r a f t 16 other Rhytismataceae species worldwide (e.g. : Wang et al 2014;Koukol et al 2015;Masumoto et al 2015;Zhang et al 2015). Furthering our understanding of the biodiversity and taxonomy of Rhytismatales species will reveal insight into the coevolution of these fungi and their hosts, provide reference sequences facilitating the identification of sequences from endophyte and other ecological surveys, and potentially lead to the identification of novel bioactive secondary metabolites.…”

Tryblidiopsis magnesii sp. nov. from Picea glauca in Eastern Canada

“…Furthermore, the ongoing descriptions of novel Rhytismataceae species, cryptic and otherwise, from Asia also indicate a greater global species diversity than previously recognized (e.g. : Kaneko 2003, Fan et al 2012, Masumoto et al 2015, Zhang et al 2015, Li et al 2016. Rhytismataceae host preferences should be further investigated, especially for putative host-jumping in introduced trees.…”