Cirrosporium novae-zelandiae, an enigmatic coelomycete with meristem arthroconidia, with ancestors in the Eurotiomycetes.

A culture of Cirrosporium novae-zelandiae, the type species of a distinctive, monotypic coelomycete genus, was isolated from a specimen collected near the holotype locality in New Zealand. Light microscopic and environmental scanning electron microscopic observations confirm the details of the unusual meristem arthric conidium ontogeny presented in the protolog. For phylogenetic analysis, a dataset of 122 species representing nine classes of euascomycetes was assembled including sequences from nuclear small and large subunits (nc18S, nc28S) and mitochondrial small subunit (mr16S) ribosomal RNA and the largest and second largest subunits of RNA polymerase II (RPB1, RPB2). A five-gene phylogeny suggests that the fungus is phylogenetically related to the Eurotiomycetes. It sits alone on a long branch as a sister to the Mycocaliciales of the Mycocaliciomycetidae. Cirrosporium exhibits several morphological characters similar to those of members of the Mycocaliciales; however, the paucity of known anamorphs in this order does not offer any further clarification on possible relationships. It is clear that the rare and broadly distributed meristem arthric ontogenetic pattern is polyphyletic, occurring in widely separate groups of anamorphs of both the Ascomycota and Basidiomycota.