Pythium campanulatum sp. nov., isolated from the rhizosphere of maize, its taxonomy, ITS region of rDNA, and comparison with related species.

Pythium campanulatum sp. nov. was isolated from some soil samples taken in the rhizosphere of maize (Zea mays) in north-eastern India. This species is characterized by the absence of zoospores and sporangia, antheridial branches wrapping around the oogonia leaving one to two campanulate antheridial cells after fertilization, and aplerotic oospores. The ITS region of its rDNA is comprised of 922 bases. This oomycete is closely related to Pythium orthogonon, Pythium nunn and Pythium toruloides. However, it has its own characteristic features and is completely devoid of zoospores. Taxonomic description of this new species and its comparison with related oomycetes, together with the sequence of the PCR-amplified internal transcribed region (spacers ITS1, ITS2, and the gene 5.8S) of its rDNA are given here.