Abstract
Two new homothallic species are described in the genus Mortierella. Mortierella cogitans sp. nov. has mesotonously branched sporangiophores with large subglobose sporangiospores and characteristic zygospores in which both of the macro- and microgametangia originate from the same branch of sexual hyphae. Mortierella microzygospora sp. nov. possesses unbranched relatively large sporangiophores and produces minute zygospores. Homothallism of these species was proven on the basis of single-spore cultures and morphological observations of their zygosporogenesis.