Mortierellomycotina subphyl. nov., based on multi-gene genealogies

The Mucoromycotina unifies two heterogenous orders of the sporangiferous, soilinhabiting fungi. The Mucorales comprise saprobic, occasionally facultatively mycoparasitic, taxa bearing a columella, whereas the Mortierellales encompass mainly saprobic fungi lacking a columella. Multi-locus phylogenetic analyses based on eight nuclear genes encoding 18S and 28S rRNA, actin, alpha and beta tubulin, translation elongation factor 1alpha, and RNA polymerase II subunits 1 and 2 provide strong support for separation of the Mortierellales from the Mucoromycotina. The existence of a columella is shown to serve as a synapomorphic morphological trait unique to Mucorales, supporting the taxonomic separation of the acolumellate Mortierellales from the columellate Mucoromycotina. Furthermore, irregular hyphal septation and development of subbasally vesiculate sporangiophores bearing single terminal sporangia strongly correlate with the phylogenetic delimitation of Mortierellales, supporting a new subphylum, Mortierellomycotina.