Echinochlamydosporium variabile, a new genus and species of Zygomycota from soil nematodes

During a recent survey of fungi colonizing juveniles of the soybean cyst nematode, Heterodera glycines, a fungus producing spiny chlamydospores and monosporous sporangia was isolated. Based on morphology and sequences of the rDNA ITS region and 18S and 28S genes, the fungus greatly resembles some species of Mortierella. Although the new isolate's spiny chlamydospores and delicate arachnoid-like mycelium are very similar to those of Mortierella, it differs significantly from Mortierella in its overall colony appearance and odour, unispored sporangium with a small columella, chlamydospores born laterally on short hyphae, and especially in its phylogenetic position. A new genus and new species, Echinochlamydosporium variabile, in Mortierellaceae (Mortierellales, Zygomycota) are proposed. A key to the genera of Mortierellaceae is provided.