Cryphonectria carpinicola is an ascomycetous fungus that has been regularly found in its asexual form on European hornbeam (Carpinus betulus) in Europe over the past two decades. Here we describe the discovery of C. carpinicola in Japan and report for the first time its sexual state on Carpinus species. No symptomatic trees were observed, but stromata were found saprotrophically on broken branches of Carpinus species on the forest floor. The sexual structures of C. carpinicola resembled that of other Cryphonectria species and strongly resembled those of the closely related species C. radicalis. A phylogenetic tree based on the internal transcribed spacer sequences showed monophyly for the Japanese and European isolates of C. carpinicola. Further studies on the distribution and host range of C. carpinicola in Japan and on the life history strategies of this fungus are needed.

Aero-aquatic fungi compose an ecological group of saprophytes inhabiting the submerged decaying substrates in stagnant freshwater environment. They produce three-dimensional shaped, multi-cellular conidia, which float on water surface by holding air between conidial cells. Because the conidia show diverse morphology, genus and species level classification have been based on their features. They are mostly known as asexual morphs of Ascomycota or Basidiomycota. Recent phylogenetic study revealed the aero-aquatic fungi appeared mainly in the lineages of Leotiomycetes, Dothideomycetes, and Sordariomycetes. Furthermore, the phylogenetic tree showed the aero-aquatic fungi have polyphyletic origins and similar three-dimensional conidial morphology generated as a convergent evolution among different lineages of fungi by the selection pressure for inhabiting freshwater environment. Recent studies suggested the ancestors of the aero-aquatic fungi were terrestrial fungi.