Molecular and Morphological Characterization of Two New Species of Globisporangium from Southern China, G. pengfuense and G. tenuihyphum

Abstract

Two new species of Globisporangium, G. pengfuense and G. tenuihyphum, that were isolated from soybean in China are described and illustrated based on their morphological characters and molecular evidence. The characteristics of G. pengfuense include globose to sub-globose sporangia that are: catenulate, terminal, occasionally with apical papillae or intercalary, smooth oogonia, mostly monoclinous, occasionally diclinous antheridia, fist-shaped to crook-necked, with straight or curved antheridial cells, and plerotic or nearly plerotic with thin-walled oospores (0.5–1.0 µm). Globisporangium tenuihyphum differs from other species in this genus by its relatively narrow hyphae that are: mostly sub-globose to globose, occasionally ovoid-obpyriform sporangia, smooth oogonia, monoclinous antheridia, subclavate, falcate or semicircular to subcircular antheridial cells, and with aplerotic oospores. Phylogenetically, data from the combined internal transcribed spacer (ITS) and cytochrome c oxidase subunit I (Cox1) sequences support the designation of G. pengfuense and G. tenuihyphum as two distinct species of Globisporangium (Pythium sensu lato clades G and J). In addition, the two new species were compared to closely related Globisporangium species, to delineate their phylogenetic positions and morphological features.