Two new species in a new genus and a critical revision of Brachybasidiaceae (Exobasidiales, Basidiomycota) in honor of Franz Oberwinkler

Abstract

The Brachybasidiaceae are a family of 22 known species of plant-parasitic microfungi belonging to Exobasidiales, Basidiomycota. Within this family, species of the largest genus Kordyana develop balls of basidia on top of stomatal openings. Basidial cells originate from fungal stroma filling substomatal chambers. Species of Kordyana typically infect species of Commelinaceae. During fieldwork in the neotropics, fungi morphologically similar to Kordyana spp. were found on Goeppertia spp. (syn. Calathea spp., Marantaceae), namely on G. panamensis in Panama and on G. propinqua in Bolivia. These specimens are proposed as representatives of a genus new to science, Marantokordyana, based on the distinct host family and molecular sequence data of ITS and LSU rDNA regions. The specimens on the two host species represent two species new to science, M. oberwinkleriana on G. panamensis and M. boliviana on G. propinqua. They differ by the size and shape of their basidia, molecular sequence data of ITS and LSU rDNA regions, and host plant species. In the past, the understanding of Brachybasidiaceae at order and family level was significantly improved by investigation realized by Franz Oberwinkler and his collaborators at the University of Tübingen, Germany. On species level, however, our knowledge is still very poor due to incomplete species descriptions of several existing names in literature, scarceness of specimens, as well as sequence data lacking for many taxa and for further barcode regions. Especially species of Kordyana and species of Dicellomyces are in need of revision.

Kordyana commelinae Associated with White Smut-like Disease on Commelina communis and C. minor in Korea

“…Several species of Kordyana, in particular K. brasiliensis, K. tradescantiae, and K. celebensis, are considered promising candidates for biocontrol of invasive weeds, such as Tradescantia fluminensis in Australia, New Zealand, and China and C. benghalensis in the United States and China [4][5][6]. Although Kordyana is the oldest genus in Brachybasidiaceae, knowledge at the genus and species level is still incomplete owing to taxonomic problems and the lack of morphological descriptions and DNA sequencing for some species [7]. In this study, we identified and described a species of Kordyana, newly found on C. communis and C. minor, based on morphological characteristics and molecular phylogenetic analyses.…”

“…Rhamphospora nymphaeae (GenBank accession nos. NR119615 and NG057757) was used as an outgroup taxon per the phylogenetic results of Piepenbring et al [7]. Two phylogenetic trees were constructed for the sequences of both the ITS and LSU regions using MEGA7 software [11] based on neighbor-joining (NJ) analysis with the following conditions: gaps in the sequence alignment were treated as deletions, evolutionary distances were calculated using the Kimura-2-parameter model, including substitutions of transitions and transversions, and bootstrap values for branches were calculated using one thousand replicates.…”

“…All substomatal chambers within abaxial lesions were filled with fungal hyphae and whitish caespituli (tufts of basidia and basidiospores) protruded directly from stomatal openings with a dense and even distribution ( Figure 1(C) ). The presence of balls of basidia developing through stomatal openings is one of distinctive characteristics of the genus Kordyana [ 7 ].…”

“…The basidiospores of the fungus were shorter than those of K. tradescantiae (15–18 μm) and K. polliae (15–21 μm), but more slender than those of K. pinangae (6–11 × 4–6 μm) [ 4 ]. Diagnostic descriptions of K. indica are lacking, and it is doubtful that the fungus is any of the other three species (i.e., K. boswelliae , K. cyphelloidis , and K. polliniae ) given that their hosts are not in the family Commelinaceae [ 4 , 7 ].…”

“…This novel collection of K. commelinae in Korea, along with the information we have provided, is expected to be a valuable source for further studies on the biological control of C. communis . As well, we hope that the study contributes to further understanding of Kordyana species, especially with regard to species delimitation and taxonomic problems [ 7 ].…”