Phylogeny and taxonomic revision of the genus Candelabrum, aero-aquatic fungi

Abstract

Abstract The genus Candelabrum, an aero-aquatic fungus, produces chandelier-shaped conidia that can float on the water. Seven species have been described in the genus. Our phylogenetic analysis based on the D1/D2 regions of the large subunit rDNA (LSU) revealed that the genus Candelabrum contains two separate lineages, C. spinulosum group (C. clathrosphaeroides, C. desmidiaceum, C. japonense, and C. spinulosum, the type species) nested in Leotiomycetes, and C. brocchiatum group (C. brocchiatum and C. microsporum) in Sordariomycetes. The two groups were distinctive in conidial morphology, especially for the presence/absence of the conidial basal plate. To accommodate the latter group, a new genus Brocchiosphaera is proposed along with a new species, B. bulbiformis. Furthermore, the phylogenetic tree inferred from LSU indicated that C. spinulosum group was closely related to Hyaloscypha in Helotiales, whereas Brocchiosphaera (the C. brocchiatum group) belonged to Pisorisporiales. Strains of H. occulta (NBRC 108595 and SANK 13397) clustered with C. japonense and C. clathrosphaeroides in phylogenetic tree inferred from combined sequence data of the RNA polymerase II gene, the internal transcribed spacer regions and 5.8S rDNA (ITS) and LSU, and NBRC 108595 produced conidia of C. japonense in submerging culture. Thus, H. occulta was proved to be a teleomorph of C. japonense. This finding warrants transferring all species of the C. spinulosum group (Candelabrum sensu stricto) to Hyaloscypha and proposing four new combinations H. desmidiacea, H. japonensis, H. macrospora, and H. spinulosa.