Tubeufia asiana, the teleomorph of Aquaphila albicans in the Tubeufiaceae, Pleosporales, based on cultural and molecular data

Abstract

The teleomorph of Aquaphila albicans was discovered on submerged wood collected in Thailand. Its black, soft-textured, setose ascomata, bitunicate asci and hyaline to pale brown, multiseptate ascospores indicated an affinity to Tubeufiaceae (Dothideomycetes). After morphological or molecular comparisons with related species in Tubeufia, Acanthostigma and Taphrophila, it is described and illustrated as a new species, T. asiana Sivichai & K.M. Tsui, sp. nov. Finding this Tubeufia teleomorph was surprising, given the falcate conidia of its A. albicans anamorph, which superficially resemble the conidia of Fusarium and not the coiled, helicosporous conidia of other species in Tubeufiaceae. We assessed the phylogenetic relationships of A. albicans-T. asiana with ribosomal sequences from SSU and ITS and partial LSU regions by parsimony and Bayesian analysis. An initial set of 40 taxa representing a wide range of ascomycete families and their SSU sequences from GenBank showed A. albicans-T. asiana to be nested within the Tubeufiaceae with 100% bootstrap support. Their placement was inferred with ITS and partial LSU ribosomal sequences. The nearly identical ITS sequences of two isolates of A. albicans and one isolate of Tubeufia asiana united these fungi as a monophyletic group with 100% bootstrap support and further nested them, with 88% bootstrap support, in a clade containing Helicoon gigantisporum and Helicoma chlamydosporum. This is the first molecular phylogenetic study to place a nonhelicosporous species within the Tubeufiaceae and to show that helical conidia were lost at least once within the family.

• Acanthostigma
• aquatic
• freshwater
• phylogeny
• systematics
• Taphrophila
• Tubeufia
• Tubeufiaceae

CKM Tsui is grateful to the Croucher Foundation for the award of a postdoctoral fellowship. NSERC provided support through an operating grant to Mary Berbee. TRF/BIOTEC special Program for Biodiversity Research and Training grants BRT 143016 and BRT 145006 is thanked for supporting freshwater fungal research in Thailand. We are grateful for type and authentic specimens and cultures for identification and confirmation by IMI, MUCL and UAMH; for technical assistance provided by SeaRa Lim and Patrik Inderbitzin; and for photographic assistance of the Electron Microscopy Unit at UBC.